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GVN Bulletin, November 2004
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From: Ed Venzke <venzke@volcano.si.edu>

Bulletin of the Global Volcanism Network
Volume 29, Number 11, November 2004

Andaman Islands (India) False reports of eruptions and confusion following
the M 9 earthquake
Ijen (Indonesia) News report cites increased activity beginning on 17 June 2004
Soputan (Indonesia) 12 December eruption covered villages with ash up to 2
cm thick
Manam (Papua New Guinea) Vigorous late-2004 eruptions cause 5 deaths and
lead to large evacuations
Erta Ale (Ethiopia) On 4-5 December 2004 visitors noted active hornitos but
solidified lava lake
Cotopaxi (Ecuador) Seismically quiet in January-April 2004; planning for
emergency water supplies
Reventador (Ecuador) Late 2004 visits find renewed venting and thick
intracaldera lava flows 2 km long
Fuego (Guatemala) Explosions and lava flows continued in November-December 2004


Dedicated to victims and survivors of the 26 December 2004 earthquake and
tsunami

As we go to press with this issue of the Bulletin our thoughts repeatedly
turn to the victims and survivors of the disastrous 26 December M 9
earthquake and tsunami. Although a different geologic process than we
discuss here, tsunamis are sometimes associated with volcanism. Conversely,
large earthquakes can trigger eruptions. The world has much to learn about
these and related geologic phenomena and about how to gauge, discuss, and
prepare for infrequent but potentially devastating events. We offer our
condolences and encouragement as we look towards a more integrated,
educated world.


Editors: Rick Wunderman, Edward Venzke, and Gari Mayberry
Volunteer Staff: Robert Andrews, Jacquelyn Gluck, William Henoch, and Aditi
Bhaskar


Andaman Islands
Indian Ocean, India
12.29°N, 93.88°E; summit elev. 305 m
All times are local (= UTC + 5 ½ hours)

False reports of volcanism surfaced describing eruptions at Barren Island
and Narcondum volcanoes (figure 1) following the 26 December 2004, M 9
earthquake off the W coast of northern Sumatra. Clarification was provided
by Dornadula Chandrasekharam of the Indian Institute of Technology. He
reported an absence of volcanic activity at these volcanoes, and at
Sumatran volcanoes, as recently as 4 January 2005.

Figure 1. A map of the Andaman Islands showing the only volcanoes known to
have erupted during the Holocene period (past 10,000 years), Narcondum and
Barren Island (N and B, respectively). Note that narrow straits break
Andaman island into multiple smaller islands (eg., Middle Andaman and
Baratang islands). Baratang Island contains an established, studied, active
mud volcano that reactivated after the M 9 earthquake.

The erroneous accounts were discovered by Chandrasekharam while watching
television news. He immediately contacted people in the Andaman region.
Upon learning that these reports were incorrect, he contacted media sources
and the Global Volcanism Network. Many Indian news sources that proclaimed
eruptions at Barren Island later withdrew their reports. The erroneous
information prevailed for a day to perhaps a week, although non-Indian news
agencies were slower to recognize and acknowledge the error.

Regional tectonic setting. Figure 2 illustrates the rudiments of the
regional tectonic setting, including the primary M 9 earthquake and
aftershocks for the next 10 days. The tectonic reconstructions are far more
complex than shown here, and the details are variously interpreted.

Figure 2. Map showing the broad tectonic setting on which Barren Island and
Narcondam volcanoes reside. The map began with the main shock of the M 9
earthquake and the earthquakes that followed during the next 11 days. USGS
preliminary tabulations computed the main shock as Mw 9.0 with a focus at
30 km depth.

In terms of local time (in the Andaman Islands and India, i.e. India
Standard Time), the epicenters shown occurred during the time interval
06:28:53 on 26 December to about 06:57 on 6 January. (In terms of UTC, this
represents the interval 00:58:53 on 25 December to about 19:57 on 5 January
2004). This digital map was extracted by applying a video simulation of
epicenters with time (Jones and others, 2002) to the recent seismic data.

The figure shows two prominent curving tectonic features crossing both
Java-Sumatra and the Andaman Sea (the Nicobar and Andaman Islands region).
One such curving feature is the volcanic front, on which lie all the active
volcanoes of Java and Sumatra, and farther N, Barren Island and Narcondam.
Outboard of that (to the W) is the second curving feature, the Sunda trench
and islands adjacent to it (the Andaman Islands, and islands to the W of
northern Sumatra hard-hit by the M 9 earthquake and tsunami). The trench
reflects the sea-floor expression of the subduction zone, and represents
the region where the M 9 earthquake occurred. The offset, often termed a
'megathrust,' involved 1,200 km of rupture along the subduction zone, and
suddenly shifted the Indian Ocean's floor ~15 m towards Sumatra (Hopkin, 2005).

Regarding the M 9 earthquake, according to the USGS, the local time and
date in terms of local time in N Sumatra at the epicenter was Sunday, 26
December 2004 at 07:58:53 (i.e., roughly 8 am). The USGS provided a table
showing the time of the main shock in a variety of time zones.

Some excellent tutorials have provided background on the tectonic setting,
the earthquake, and the tsunami. These have appeared in the press and on
the web (eg. Sieh, 2004, 2005; NOAA, www.noaa.gov/tsunamis.html).
Although large earthquakes may trigger volcanism (Linde and Sacks, 1998),
so far this does not appear to be the case, at least at the volcanoes of
Barren Island and Narcondum.

Mud volcanoes and ensuing confusion. Post-earthquake reports of active 'mud
volcanoes' in the Andaman Islands caused panic and confusion in the region,
and came at a particularly bad time. Chandrasekharam pointed out that in
Andaman, like many other arc provinces, several mud volcanoes are present.
These are not real volcanoes in the usual sense, but because they may build
a small, low-profile cone of local extent around the hole through which the
mud is thrown out, they are known as mud volcanoes (figure 3).

Figure 3. A 2003 photograph showing about a quarter to one half of a mud
volcano on Baratang island (top) and its largest crater (~ 20 cm in
diameter, ~ 28 cm in depth) (bottom). This site was known as a minor
fissure prior to 1983; but in that year the largest outburst occurred,
chiefly emitting warm (~ 30°C) mud. Mud again began emerging in February
2003. The dominant feature was a sub-circular mound of mud, ~ 30 m in
diameter with a height of ~ 2 m at the center. Observers noted a colorless,
sulfurous smelling gas. The mud contained angular to sub-rounded rock
fragments from underlying strata. No photos nor similarly detailed
technical reports have been received showing alleged recent activity that
began 27 December 2004 (see text for news report). All photos and data
courtesy of the Geological Survey of India, Eastern Region.

Some of the difficulty with the news reports was that the mud volcanoes'
locations, numbers, and impacts remained vague, and that Barren Island
became intertwined with story. An extreme example came from an
irresponsible report in the tabloid India Daily (2 January 2005), which
contained the title "Volcano[es] Barren-1 and Narcondam erupt in
Andaman--Seismic disturbance can cause more tsunami." It continued with
wild claims such as, "Severe seismic activities are seen in these islands .
. . personnel who have reached these remote areas are facing shattering
earth vibrations and high waves," and "Some scientists are predicting
severe earthquake again in the North of Andaman Nicobar Islands. The effect
can be severe on Myanmar, Andaman, Indi[a]'s east coast, Bangladesh and
Sumatra . . .." They added, "Andaman's tribals strangely are unaffected as
most of them somehow went [to] higher ground before the tsunami. So did the
animals." Science journalism clearly has a lot to compete with (see
Oldenburg, 2005, for more discussion of these topics).

One alleged mud volcano 'Barren-1' has a name so close to the volcano's
name (Barren Island) that it was frequently confused. The mud volcano's
name (if there is one) appears to be absent from the technical literature
at the Geological Survey of India's website.

On a positive note, one mud volcano received consistent mention in a number
of news articles and provided coverage generally congruent with geological
data posted by the Geological Survey of India. According to an article in
India News (with the leader, "Port Blair, 30 December"), "A mud volcano at
the inhabited Baratang Island in Middle Andaman has erupted but the
administration said there was no cause for concern. 'Mud keeps bubbling in
the volcano, but on December 28, the eruption was up to three meters and
there was considerable heat,' Inspector General of Police S. B. Deol said
here."

"He [also] said the mud volcano was located on one side of the Baratang
Island, which was about 100 km from Port Blair. People live on the other
side, but there is no cause for concern."

A report in the India Daily was nearly identical. Details on a Geological
Survey of India website noted that the Baratang mud volcano began erupting
on 27 December 2003 (figure 3 and caption). Mud volcanoes may have also
occurred elsewhere in the region, but the available news reports
consistently failed to disclose locations.

Often associated with active faults and with petroleum fields, mud
volcanoes on land consist of low-lying surface mud extrusions that vary in
size from meters to several kilometers across. They emit mud at
temperatures significantly below magmatic, which are typically at least
800°C. Eruptions from mud volcanoes can reach heights of several hundred
meters and consist of mud, fluids and gases, and sometimes burning
hydrocarbons. Although in submarine environments mud volcanoes can be
extensive, deadly mud volcano eruptions are extremely rare because their
eruptions seldom move far enough to affect large areas of the land
surface. Their greatest danger may be to curious onlookers who venture too
close.

References. Jones, A., Siebert, L., Kimberly, P., and Luhr, J.F., 2002,
Earthquakes and Eruptions, v. 2.0 (CD-ROM): Smithsonian Institution, Global
Volcanism Program, Digital Information Series, GVP-2.

Hopkin, M., 2005, Triple slip of tectonic plates caused seafloor surge:
Nature, v. 433, no. 3 (06 Jan 2005).

Linde, A.T., and Sacks, I.S., 1998, Triggering of volcanic eruptions:
Nature, v. 395, p. 888-890.

Oldenburg, D., 2005, A sense of doom: Animal instinct for
disaster--Scientists investigate wildlife's possible warning systems: The
Washington Post (8 January 2005), p. C1, C3 (URL:
www.washingtonpost.com/).

Sieh, K., 2004, The science behind the Aceh earthquake: Caltech Media
Relations (30 December 2004), (URL:
pr.caltech.edu/media/Pres...2628.html).

Sieh, K., 2005, In Sumatra: Notes From a Geologist in the Field: Caltech
Today (1 January 2005; URL: today.caltech.edu/today/).

U.S. National Earthquake Information Center (NEIC) (URL:
earthquake.usgs.gov)./

U.S. National Oceanic and Atmospheric Administration (NOAA) (URL:
www.noaa.gov/tsunamis.html).

Background. Barren Island, a possession of India in the Andaman Sea about
135 km NE of Port Blair in the Andaman Islands, is the only historically
active volcano along the N-S-trending volcanic arc extending between
Sumatra and Burma (Myanmar). The 354-m-high island is the emergent summit
of a volcano that rises from a depth of about 2,250 m. The small,
uninhabited 3-km-wide island contains a roughly 2-km-wide caldera with
walls 250-350 m high. The caldera, which is open to the sea on the W, was
created during a major explosive eruption in the late Pleistocene that
produced pyroclastic-flow and -surge deposits. The morphology of a fresh
pyroclastic cone that was constructed in the center of the caldera has
varied during the course of historical eruptions. Lava flows fill much of
the caldera floor and have reached the sea along the western coast during
eruptions in the 19th century and more recently in 1991 and 1995.

Narcondum volcano, an island possession of India in the Andaman Sea, is
part of a volcanic arc that continues northward from Sumatra to Burma
(Myanmar). The small 3 x 4 km wide conical island, located about 130 km
east of North Andaman Island, rises to 710 m, but its base lies an
additional 1,000 m beneath the sea. The island is densely vegetated,
bounded by cliffs on the southern side, and capped by three peaks. No
evidence of historical volcanism is present, although the summit region is
less densely vegetated and volcanism at the andesitic volcano is considered
to have continued into the Holocene. The island's name means "pit of hell,"
although the name could have been mistakenly transferred from the
historically active Barren Island volcano, 140 km to the SSW.

Information Contacts: Dornadula Chandrasekharam, Department of Earth
Sciences, Indian Institute of Technology, Bombay 400076, India (URL:
www.geos.iitb. ac.in/dchandra/biexp/, Email: dchandra@iitb.ac.in);
India News (URL: news.newkerala.com/india-news/); India Daily (URL:
www.indiadaily.com/); The Washington Post, Washington DC, USA (URL:
www.washingtonpost.com/); Geological Survey of India, 27 Jawaharlal
Nehru road, Kolkata (Calcutta) 700016, India.


Ijen
eastern Java, Indonesia
8.058°S, 114.242°E; summit elev. 2,386 m
All times are local (= UTC + 7 hours)

The Chief of the local National Park has been quoted as having reported an
increase in activity beginning on 17 June 2004. This resulted in closing
the area to visitors. Reuters quotes him as having said "There have been
sulfuric rocks coming out of the edge of the crater and the fluid in it
(the crater lake) has turned from green to white and has emitted hot foam.
There are also increasing tremors."

Background. The Ijen volcano complex at the eastern end of Java consists of
a group of small stratovolcanoes constructed within the large 20-km-wide
Ijen (Kendeng) caldera. The N caldera wall forms a prominent arcuate ridge,
but elsewhere the caldera rim is buried by post-caldera volcanoes,
including Gunung Merapi stratovolcano, which forms the 2,799-m-high point
of the Ijen complex. Immediately W of Gunung Merapi is the renowned
historically active Kawah Ijen volcano, which contains a nearly 1-km-wide,
turquoise-colored, acid crater lake. Picturesque Kawah Ijen is the world's
largest highly acidic lake and is the site of a labor-intensive sulfur
mining operation in which sulfur-laden baskets are hand-carried from the
crater floor. Many other post-caldera cones and craters are located within
the caldera or along its rim. The largest concentration of post-caldera
cones forms an E- to W-trending zone across the southern side of the
caldera. Coffee plantations cover much of the Ijen caldera floor, and
tourists are drawn to its waterfalls, hot springs, and dramatic volcanic
scenery.

Information Contact: Reuters News Service.


Soputan
Sulawesi, Indonesia
1.11°N, 124.73°E; summit elev. 1,784 m
All times are local (= UTC + 8 hours)

Soputan erupted again on 12 December 2004. The Directorate of Volcanology
and Geological Hazard Mitigation (DVGHM) noted that an eruption on 18
October 2004 sent a cloud ~600 meters above the crater. The previous
eruptive episode occurred during July and August 2003 (Bulletin v. 28, nos.
8, 10, and 11). A summary of ash plumes from mid-2003 through 12 December
2004 appears in table 1. Large discrepancies appeared in reported ash
column heights; with the satellite estimates about 10 times larger than
ground-based estimates.

Table 1. Reported ash plume altitudes recorded from Soputan, 18 July
2003-12 December 2004. Courtesy of DVGHM and Darwin VAAC.

Date Height (km) (comment) Source

18 Jul 2003 ~ 2 km above summit DVGHM
02 Sep 2003 ~ 2 km altitude Darwin VAAC
04 Sep 2003 ~ 3 km altitude Satellite imagery, Darwin VAAC
(extending ~ 75 km N
of the summit)
18 Oct 2004 ~ 600 m above summit DVGHM
12 Dec 2004 ~ 1 km above summit DVGHM
12 Dec 2004 ~ 10.7 km altitude Darwin VAAC

The earliest details mentioned by DVGHM regarding the 2004 activity
discussed 11 December 2004, a time when the tremor tended to rise,
attaining peak-to-peak amplitudes of 0.5-3.0 mm. Observers also saw
incandescence at the crater's rim.

At 0046 on 12 December tremor again registered with maximum peak-to-peak
amplitudes of ~45 mm. At 0050 on 12 December Soputan erupted, sending an
ash cloud up to 1 km. This was followed by discharge of a "hot cloud"
(pyroclastic flow ?) to a distance of ~200 m E (from 'Aeseput,' a prominent
NE-flank vent that formed in 1906). A lava flow spread W and S of Soputan.
Observers could hear rumbling noise and thunder from their monitoring
station ~11 km from the crater.

White-to-gray ash went E. At 0130 on 12 December a problem arose with the
seismic sensors, perhaps because the solar panel was covered with ash. By
0600 the sensor was down. At 0500 that day a hot cloud occurred with a run
out distance of ~150 m and a height of 200 m. Activity persisted until
1030. Soputan's summit then became visually obscured by clouds, but
observers could still make out a white thin-to-medium plume to 70-80 m
above the crater, and incandescence.

On the 13 December at 1752 observers felt an earthquake with a magnitude of
MM I-II. The seismograph was then still inoperable.

News reports. A 13 December news report in The Daily Reform Voice stated
that hundreds of hectares of paddy-fields and other agricultural land to
the W of the Soputan was seriously impacted by tephra.

Thomas Dobat, a German expatriat living in Indonesia and concerned about
the situation, sent Bulletin editors a translation of a 13 December 2004
article on Soputan taken from the Indonesian Journal Komentar. Similar to
the above report, it also noted that hundreds of villages in 13 districts
in Central Minahasa and in South Minahasa suffered from tephra fall emitted
on 11-12 December. These eruptions of Soputan were accompanied by heavy
thunder and lightning, which were heard in the town of Amurang.

Ash fell in nearly all of Central Minahasa and in parts of South Minahasa.
The result was that in all areas of Central Minahasa, especially in the
town of Tondano, houses, rice-fields, and roads were ash-covered up to 2 cm
thick.

Background. The small Soputan stratovolcano on the southern rim of the
Quaternary Tondano caldera on the northern arm of Sulawesi Island is one of
Sulawesi's most active volcanoes. The youthful, largely unvegetated volcano
rises to 1784 m and is located SW of Sempu volcano. It was constructed at
the southern end of a SSW-NNE trending line of vents. During historical
time the locus of eruptions has included both the summit crater and
Aeseput, a prominent NE-flank vent that formed in 1906 and was the source
of intermittent major lava flows until 1924.

Information Contacts: Directorate of Volcanology and Geological Hazard
Mitigation, Jalan Diponegoro 57, Bandung 40122, Indonesia (Email:
dali@vsi.dpe.go.id; URL: www.vsi.esdm.go.id/); Darwin Volcanic Ash
Advisory Centre, Australian Bureau of Meteorology (URL:
www.bom.gov.au/info/vaac); The Daily Reform Voice; Komentar; Thomas
Dobat, Lorong Jerman, Kauditan II, 95372, Sulawesi Utara, Indonesia.


Manam
Papua New Guinea, Northeast of New Guinea
4.10°S, 145.061°E; summit elev. 1,807 m
All times are local (= UTC - 10 hours)

Several periods of eruption took place on the island of Manam during the
last months of 2004. Rabaul Volcano Observatory (RVO) noted outbursts
during 24-31 October (Bulletin v. 29, no. 10), 10-12 November, and on 6
December. Several other plumes were noted as well. Satellite-based alerts
(MODVOLC) were noteworthy during this interval, having been absent for over
9 months.

On 6 December, the newspaper The National reported that these eruptions had
killed five people, whose deaths were primarily related to respiratory
complications from inhaling volcanic material. Volcanic ash damaged crops,
water supplies, and houses. News accounts discussed evacuations, with the
possibility of evacuating all or most of the island (figure 4). The news
also mentioned food shortages after the 24 October eruption.

Figure 4. Geography of the area around Manam showing two named villages on
the island and numerous settlements on the main island of New Guinea. For
scale, Manam Island is ~ 10 km in diameter. The volcano is sometimes
referred to as Mount Iabu in the regional press. The city of Wewak lies off
the map, ~ 160 km W of Manam; the city of Madang lies ~ 150 km to the E.
The large meandering river at left is the Sepik. The island's residents, a
total of 9,467 people, rely on subsistence farming and fishing for food,
and copra and cocoa as a source of income. Map courtesy of Jorgen Aabech.

The government of Papua New Guinea presented a new website, The National
Disaster Center, which broadly disseminates government disaster information
including volcano reports and updates (see URL under Information Contacts,
below). The website contained a Manam hazards map. Other documents on that
site noted shifting winds and the lack of a clearly safe area on the island
during the late 2004 crisis. It said that the government would sponsor
large-scale evacuations beginning on 27 November 2004.

The eruptive episode that began on 24 October continued at least a week
(figure 5). By 31 October, the eruption at Main Crater consisted of
Strombolian activity, with ash and scoria emissions. Tephra of ~1 cm
diameter were deposited in Warisi village on the SE side of the island.
Small pyroclastic flows were generated, and fresh lava flowed into the NE
radial valley. The lava flow followed the Boakure side of the valley,
covering older flows from the 1992-1994 eruption. Beginning on the morning
of the 31st, the amount of continuous volcanic tremor increased to
moderate-to-high levels, so the Alert Level was increased from Stage 1 to
Stage 2. Villagers were advised to remain away from Manam's four main
radial valleys.

Figure 5. Image of Manam and vicinity acquired on 24 October 2004 by the
Moderate Resolution Imaging Spectroradiometer (MODIS), an instrument on the
Terra satellite of the National Aeronautics and Space Administration
(NASA). Dark ash rising from Manam drifted NW along and then away from the
N coast of the main island, New Guinea. Courtesy NASA Earth Observatory.

The Darwin Volcanic Ash Advisory Center reported the 24 October outburst
(Bulletin v. 29, no. 11). On 31 October during 0813-1449 they noted a plume
at ~13.7 km altitude drifting SE on visible satellite imagery. The Aviation
Color Code was at Red, the highest level.

According to a news report, ". . . [~0.3 m] of ash with hot pumice" landed
on the roofs of houses, and ash drifted as far W as Wewak, ~100 km away.
Reportedly, ~4,000 villagers moved to safer areas.

On 2 November around 2325 a possible eruption may have produced a plume to
~7.6 km altitude, which drifted SE. Ash was visible on satellite imagery on
8 and 9 November at an altitude of ~3 km; on 9 November the plume extended,
~55 km to the NE.

A Strombolian eruption occurred during 10-11 November 2004. The ash column
from the eruption was estimated to have risen ~5-6 km above the crater, and
perhaps rose as high as ~9 km above the crater, according to an Air Niugini
pilot. The activity was accompanied by continuous weak to moderate roaring
and rumbling noises and frequent loud explosions. Light ash and scoria fall
was reported near local villages. As of 2130 on 10 November ash reached 7
km altitude and 147 km to the SW. As of 12 November, the ash emissions
reached 10 km altitude and extended laterally 74 km W to NW of the volcano.

During this reporting interval Darwin VAAC noted that a SE-drifting plume
was visible on satellite imagery on 31 October during 0813-1449 at an
altitude of ~13.7 km.

A satellite image from the Terra Moderate Resolution Imaging
Spectroradiometer (MODIS) on 15 November shows a large brown ash plume
blowing SW (figure 6).

Figure 6. Manam image acquired 15 November 2004 from Moderate Resolution
Imaging Spectroradiometer (MODIS) passing overhead on the National Aviation
and Space Agency (NASA) Terra satellite. Dark ash rises from Manam and
drifts SW over New Guinea. Courtesy NASA Earth Observatory.

According to RVO scientists, on 23-24 November Main Crater ejected glowing
lava and discharged an ash cloud that rose ~10 km high. A lava flow was
also reported to be heading for two villages on the island. At 1850 on 23
November, a phase of strong Strombolian eruption began producing a
continuous, thick ash column that rose about 10 km above the summit. The
ash cloud emissions were accompanied by projection of glowing lava
fragments, loud roaring and rumbling noises, and occasional loud and
banging noises that produced shock waves. A continuous bright red glow
visible down the NE valley indicated emplacement of a lava flow.

The lava flow was reported heading NE towards villages of Kolang and Bokure
1. In addition to the lava, Manam emitted large rocks. Around this time the
aviation red alert issued for aircraft noted that the ash plume extended
130 km SE of Manam.

Press accounts stated that emergency officials said an area was being
cleared on the mainland for a possible full-scale evacuation of Manam's
~9,500 islanders. Evacuation was to become compulsory if activity
intensified from Stage 3 (which was set by 22 November) to Stage 4. Some 20
bush homes had collapsed due to 'mud rain' (presumably, falling tephra),
and five people had been injured.

RVO reported that a slight increase in eruptive activity from Main Crater
began after 1600 on 26 November, which continued until 0800 on the 29th.
Summit activity consisted of continuous forceful emission of thick dark
gray ash clouds that rose less than 1 km above the summit before being
blown NW. Fine ashfall to the NW at Zogari and Iassa villages was reported
from about 1700. A single weak roar was heard between 0600 and 0700 on the
27th.

Seismicity was moderate to moderate-high at 2300 on the 26th and 0800 on
the 27th. Volcanic tremors continued to be recorded suggesting the system
remained dynamic and capable of ongoing variable eruptions, with sporadic
more vigorous phases.

On 28-29 November, RVO reported that ash clouds were rising less than 1 km
above the summit before being blown by the shifting NNE and NNW winds. Fine
ashfall was reported at Warisi. Weak roaring noises were heard between
1900-2400 on the 28th. A weak glow with weak projections of incandescent
lava fragments was visible during the night of the 28th, and Southern
Crater released thin white vapor only.

Some press reports described 7,900 persons evacuated from Manam. According
to the Planet Diary web site, about 9,000 people were evacuated by 1
December 2004 as the eruption grew more violent.

Mid-afternoon on 5 December RVO noted a slight change in activity at
Southern Crater marked by commencement of sub-continuous weak to moderate
roaring and rumbling noises. The noises continued until 1000 that day. As
darkness fell, intervals of visibility occurred (eg., during 1800-1808,
2030-2108, and 2130-2200); observers saw sub-continuous lava fountaining.
Meanwhile, from Main Crater there came a series of sub-continuous,
forceful, moderately thick, gray-brown ash-laden clouds, which were
occasionally visible above the weather clouds. The ash plume rose between
about 600 and 900 m above the summit and drifted to the E and NE. Light
ashfall and fine scoria fell at the villages Abaria and Bokure 1.
Fluctuating audible noises consisted of low roars, 'jet engine' roars, and
occasional still-louder roars. Although visibility was generally poor due
to volcanic ash clouds from both craters, observers could still make out
variable glow coming from the craters.

On 8 December 2004, The National reported that, according to RVO, Manam
erupted starting on the morning of 6 December. Fist-sized scoria were
thrown out of the vent into the air, hitting houses in the villages below.
The eruption began at 0800 and peaked at 1150 with "seismicity continuing."

The National also reported that a pyroclastic flow occurred in the SE
valley during the 6 December eruption, with ash and cloud directed NW. On
the 6th, residents of Madang (~150 km E of Manam) described feeling tremor
or ground motion; those in Wewak (~160 km to the W) reported similar
sensations and also noted volcanically derived dust. Although ash from 6
December was apparently widespread, Googling for news of Manam ash in Irian
Jaya failed to turn up any reports from there.

The Darwin VAAC reported ash plume sightings from satellites during 12-14
December, and the RVO reported moderate eruptions continuing in that period.

Fatalities. An article by Bonney Bonsella in The National showed pictures
of Manam Islanders in evacuation. They waded through shallow surf to board
through the open bow of a large beached landing craft. The article
discussed fatalities during the eruption.

"The volcanic eruption on Manam Island in the Madang province has so far
claimed five lives-two elderly women and three children between the ages of
5-13. The coordinator of the Manam evacuation exercise Camillus Dugumi
confirmed the deaths, adding that the deaths were linked to respiratory
complications resulting from inhaling volcanic ashes and dust. Mr Dugumi,
who is also the district health programme manager, said one of the deaths
was that of an elderly women from Bokure village recorded early last week
at the Bogia District hospital. The women died after being admitted to the
hospital for respiratory complications. One child, a little boy, died on
Friday at the Asuramba care centre after suffering pneumonia."

"Three others-an adult women and two other children-had died during earlier
volcanic activity on Manam."

Displaced residents. The above-mentioned article related that three
State-owned plantations (called Asuramba, Potsdam, and Magem (and Daigul?))
were set aside, ". . . at least for the time being[,] to accommodate a
speedy resettlement of the displaced Manam islanders." Another news article
noted that these plantations are near the town of Bogia (figure 4). The
National Disaster Center website noted that "The three plantations were
bought off from the lessee in 1995 for K1.25 million following a National
Executive Council decision for the purpose of resettlement of Manam
Islanders displaced by volcanic activity." Controversies remain with
respect to land issues. Still , that website noted that the long-term
solution advocated by the President, Manam Local Level Government is to
resettle the people of Manam on the mainland. For this purpose the
Provincial Disaster Committee has identified State land to resettle the
Manam Island people.

MODVOLC. The MODIS infrared instrument flown on the NASA Terra and Aqua
satellites showed an impressive set of thermal alerts beginning 21 October
2004 (figure 7). Since the beginning of MODVOLC operations (Bulletin v. 28,
no. 1) thermal alerts occurred at Manam during only two periods. The first,
7 April-21 May 2002, was related to increased Strombolian activity
(Bulletin v. 27, no. 5). The second period, 21 October until at least 14
December 2004, was associated with the current crisis and was a time when
alert ratios and summed radiances reached higher values than during the
first period. These parameters are consistent with a highly active vent
and/or lava flows, and in accord with vigorous Strombolian emissions seen
in the field.

Figure 7. MODVOLC thermal alert ratios, number of alert pixels, and summed
4 mm radiance plots for Manam from 1 January 2001 until 31 December 2004.
Alerts occurred only between 7 April and 21 May 2002 and between 21 October
and 14 December 2004. Thermal alerts collated by Charlotte Saunders, and
David Rothery; data courtesy of the Hawaii Institute of Geophysics and
Planetology's MODIS thermal alert team.

This analysis of MODIS thermal alerts (using the MODVOLC alert-detection
algorithm) is based on data extracted from the MODIS Thermal Alerts website
maintained by the University of Hawaii HIGP MODIS Thermal Alerts team.

Thermal alerts are based on an 'alert ratio,' and an alert is triggered
whenever this ratio has a value more positive than -0.8. This threshold
value was chosen empirically by inspection of images containing known
volcanic sites at high temperature, and is the most negative value that
avoids numerous false alarms. There are also some day-time alerts, which
are based on the same algorithm but incorporating a correction for
estimated solar reflection and a more stringent threshold whereby the alert
ratio is required to be more positive than -0.6 in order to trigger an alert.

Background. The 10-km-wide island of Manam, lying 13 km off the northern
coast of the mainland Papua New Guinea, is one of the country's most active
volcanoes. Four large radial valleys extend from the unvegetated summit of
the conical 1,807-m-high basaltic-andesitic stratovolcano to its lower
flanks. These "avalanche valleys," regularly spaced 90 degrees apart,
channel lava flows and pyroclastic avalanches that have sometimes reached
the coast. Five small satellitic centers are located near the island's
shoreline on the northern, southern and western sides. Two summit craters
are present; both are active, although most historical eruptions have
originated from the southern crater, concentrating eruptive products during
the past century into the SE avalanche valley. Frequent historical
eruptions have been recorded at Manam since 1616. A major eruption in 1919
produced pyroclastic flows that reached the coast, and in 1957-58
pyroclastic flows descended all four radial valleys. Lava flows reached the
sea in 1946-47 and 1958.

Information Contacts: Rabaul Volcano Observatory (RVO), P.O. Box 386,
Rabaul, Papua New Guinea; National Disaster Centre, Department of
Provincial Affairs and Local Level Government (Ministry of Inter-Government
Relations), PO Box 4970, Boroko, National Capital District, Papua New
Guinea (URL: www.pngndc.gov.pg/); David Innes, Flight Safety Office,
Air Niugini (Email: dinnes@airniugini.com.pg or deejayinnes@yahoo.com);
Andrew Tupper, Darwin Volcanic Ash Advisory Centre, Australian Bureau of
Meteorology (URL: www.bom.gov.au/info/vaac); Jorgen Aabech,
Skogbrynet 40B, N-1709 Sarpsborg, Norway (Email: Jorgen.aabech@eunet.no;
URL: http:// www.vulkaner.no); MODIS Thermal Alert System, Hawaii Institute
of Geophysics and Planetology (HIGP), School of Ocean and Earth Science and
Technology, University of Hawaii at Manoa (URL:
www.modis.higp.hawaii.edu); David Rothery and Charlotte Saunders,
Department of Earth Sciences, The Open University, Milton Keynes, MK7 6AA,
United Kingdom (Email: d.a.rothery@open.ac.uk); Kevin Pamba and Bonney
Bonsella, The National (URL: www.thenational.com.pg/1206/).


Erta Ale
Ethiopia
13.60°N, 40.67°E; summit elev. 613 m

Two teams sent reports on Erta Ale's behavior in December 2004. On 1-5
December the visiting team included Jacques-Marie Bardintzeff and a group
from Ushuaia Nature, and on 4-5 December the team consisted of the
volcanology travel group SVE-SVG. Both groups submitted similar reports and
commented on substantial changes they observed compared to conditions
described in past reports (most recently, Bulletin v. 29, no. 8). Although
Erta Ale frequently contains a lava lake with an open surface of molten
lava, that was not the case this time.

The lava lake's surface had chilled within the small (~200-m-diameter) S
pit crater (figure 8). A solidified lava crust covered the crater floor.
The crust's surface sat ~15 m below the W crater rim, and ~30 m below the E
crater rim. On top of this crust stood four coalesced hornitos in the SE
part of the S crater (figure 9). They were ~10 m high and represented the
only portion of the crust where molten material was in evidence. Two
hornitos emitted high temperature (more than 500°C) SO2-rich gas. Another
hornito contained glowing molten lava. During the night of 4 December the
SVE-SVG group saw degassing and incandescent lava at the summit of two of
these hornitos. Bardintzeff described sampling molten material from 12 m
depth, in one of the hornitos using a cable and an iron mass (figure 9).

Figure 8. The small S pit crater at Erta Ale as viewed from the E on 5
December 2004. Hornitos had grown on the W part of the crater floor; except
for these windows into the molten material at depth, the rest of the lava
lake surface had completely solidified. Photo provided by J. M. Bardintzeff.

Figure 9. The S pit crater at Erta Ale as seen from the W on 5 December
2004, with the 4 hornitos in the center of the photo. Two hornitos on the
left emitted high temperature SO2. The hornito in the right foreground
contained molten lava (which was sampled). Photo provided by J. M. Bardintzeff.

The SVE-SVG team noted recent activity within the North crater, where an
uplifted area termed a 'lava bulge' had solidified. It covered ~80% of the
crater floor and rose to about 20-25 m below the crater rim. In the lava
bulge's central area, strong and noisy degassing of SO2 spouted from
several small hornitos. At the bulge's periphery the observers saw ten
small incandescent vents. Subsequently, two plumes rose above the volcano.

Background. Erta Ale is an isolated basaltic shield volcano that is the
most active volcano in Ethiopia. The broad, 50-km-wide volcano rises more
than 600 m from below sea level in the barren Danakil depression. Erta Ale
is the namesake and most prominent feature of the Erta Ale range. The
613-m-high volcano contains a 0.7 x 1.6 km, elliptical summit crater
housing steep-sided pit craters. Another larger 1.8 x 3.1 km wide
depression elongated parallel to the trend of the Erta Ale range is located
to the SE of the summit and is bounded by curvilinear fault scarps on the
SE side. Fresh-looking basaltic lava flows from these fissures have poured
into the caldera and locally overflowed its rim. The summit caldera is
renowned for one, or sometimes two long-term lava lakes that have been
active since at least 1967, or possibly since 1906. Recent fissure
eruptions have occurred on the northern flank of Erta Ale.

Information Contacts: Jacques-Marie Bardintzeff, Laboratoire de
Petrographie-Volcanologie, Bât. 504, Universite Paris-Sud, F-91405, Orsay,
France (Email: bardizef@geol.u-psud.fr, URL:
www.lave-volcans.com/bardintzeff.html); Henry Gaudru, Societe
Volcanologique Europeenne (SVE), C.P.1-1211 Geneva 17- Switzerland (Email:
HgaudruSVE@compuserve.com; URL: www.sveurop.org/).


Cotopaxi
Ecuador
0.677°S, 78.436°W; summit elev. 5,911 m
All times are local (= UTC - 5 hours)

Seismicity at Cotopaxi during December 2003 through December 2004 yielded
averages that generally remained within normal levels (table 2). Steam
emissions continued, and sulfurous odors were occasionally reported. A plot
of total seismicity each week during 2001-July 2004 portrayed numerous
peaks and valleys in the range 50-200 events per week. Occasional
excursions took the weekly totals to several hundred events in late 2001
and early 2002 (peaking at over 700 events per week during mid-October
2001). The 2004 data lacked such dramatic excursions.

Table 2. Annual summaries showing typical daily averages of various kinds
of seismicity at Cotopaxi during 2001-2004. Courtesy of IG (shown on their
website in the January 2005 report).

Year Volcano-tectonic Hybrid Long-period Tornillo
Tremor Total

2001 3.1 1.0 10.2 0.1 0.2
11.3
2002 2.9 3.0 14.6 0.1 0.4
18.2
2003 1.2 3.7 9.3 0.0 1.4
14.2
2004 0.41 3.59 11.10 0.0 1.56
15.11

Planning for emergency water supplies. Although seismicity and other
monitored parameters were moderate to low during most of 2003 (Bulletin v.
28, nos.11 and 12), local authorities worked on a contingency plan for
emergency drinking water in the event of a crisis at Cotopaxi.

The Quito metropolitan sanitation and drinking water company (EMAAP-Q)
prepared a contingency plan for residents around Cotopaxi. The challenge
was to provide for sufficient amounts of potable and sanitation water for
some half a million people in the event of an eruption that contaminates
their normal water supplies. This contingency plan was drawn up using
experience gained from the operational emergency plan used to recover from
the eruption in 1998-99 and the Reventador eruption in 2002.

During the Guagua Pichincha eruption, pyroclastic material impacted Quito,
and ash fell into the water treatment plants and threatened the water
supply systems. EMAAP-Q developed an operational and emergency plan. The
plan was tested in 1999 when the volcano had two major eruptions that heat
dropped ash on Quito and its infrastructure.

Background. Symmetrical, glacier-clad Cotopaxi stratovolcano is Ecuador's
most well-known volcano and one of its most active. The steep-sided cone is
capped by nested summit craters, the largest of which is about 550 x 800 m
in diameter. Deep valleys scoured by lahars radiate from the summit of the
andesitic volcano, and large andesitic lava flows extend as far as the base
of Cotopaxi. The modern conical volcano has been constructed since a major
edifice collapse sometime prior to about 5,000 years ago. Pyroclastic flows
(often confused in historical accounts with lava flows) have accompanied
many explosive eruptions of Cotopaxi, and lahars have frequently devastated
adjacent valleys. The most violent historical eruptions took place in 1744,
1768, and 1877. Pyroclastic flows descended all sides of the volcano in
1877, and lahars traveled more than 100 km into the Pacific Ocean and
western Amazon basin. The last significant eruption of Cotopaxi took place
in 1904.

Information Contact: Geophysical Institute (IG), Escuela Politecnica
Nacional, Apartado 17-01-2759, Quito, Ecuador (URL: www.igepn.edu.ec/).


Reventador
Ecuador
0.078°S, 77.656°W, summit elev. 3,562 m
All times are local (= UTC - 5 hours)

A 16 December 2004 report from the Instituto Geofisico (IG) of the Escuela
Politecnica Nacional calls attention to renewed lava effusion from the
crater that lies within Reventador's large summit cone (figure 10). A
block-lava flow escaped the cone's crater. It ran out at a breach in the S
wall, and by 16 December it had advanced ~2 km farther. The flow advanced
SE along a narrow, E-curving path, remaining atop lavas from 2002. Thus far
in 2004, lava flows remained well within the larger caldera.

Figure 10. An aerial photo of Reventador's 4-km-diameter caldera as a base
for mapping the lava flows of 2002 and those of 2004 through mid-December.
The 2002 flows are labeled Lava 1 and Lava 2. The 2004 lava flow followed
and partly covered Lava 1. At a distance of ~ 1 km from the vent, the 2004
lava flow bifurcated into two closely spaced parallel lobes. The caldera
has an E-tilting floor, is open on its E side, and contains a prominent
cone on its W side. The cone forms the volcano's summit, and contains an
elongate crater that hosts the 2004 vent ("active vent"). The crater has a
rim that is indicated by a solid curving line; the crater's inward-sloping
walls are indicated by light shading and lines resembling the trends of
gullies. The cone's floor at its southern breach lies at ~ 3,200 m
elevation. The aerial photo was taken by Instituto Geografico Militar in
1983. Figure courtesy of IG.

Reports in 2003 chiefly discussed events outside the caldera. A road, one
gas pipeline, and two oil pipelines traverse Reventador's flanks 7 km ESE
of the active vent. All of these installations were affected in 2003 (but
not appreciably since then). The pipelines were destroyed due to heavy
lahars coming down the Reventador river on 6 May 2003 (Bulletin v. 28, no.
6). Our last report (Bulletin v. 28, no. 11) discussed events during July
through most of November 2003.

Lava venting in the crater likely began in early November 2004, a time when
seismic station CONE registered dramatic increases in volcano-tectonic
events (figure 11). In response to the elevated seismicity, the IG-EPN
began more intensive monitoring, including overflights with thermal
imaging, repeat visits to the remote volcano, and on 9 November 2004,
installation of the additional short-period seismic station LAV3, ~2 km
from the crater's vent.

Figure 11. Seismicity (number of earthquakes) versus time registered at
Reventador (station CONE) during mid-February 2003 through mid-December
2004. Anomalously elevated seismicity consisting mainly of volcano-tectonic
began in August 2004. Activity increased on 4 November 2004 and included
hybrid events. Previously unseen emergent, extended-duration, broad-band
earthquakes began on 22 November 2004. Courtesy of IG.

A helicopter overflight by IG-EPN staff on 10 November 2004 confirmed the
presence of a small lava dome, which appeared then to be confined to the
crater floor. This feature was not present on photos taken during an IG
overflight on 19 October 2004. During the 10 November overflight, a
continuous 2.5 km-high gas column escaped from the crater, accompanied by
sulfurous odors detected by personnel in the helicopter.

The date when lava began escaping the crater was not precisely known, but
it was thought to have been around 22 November, coincident with the
emergence of distinct seismic signals not previously observed at Reventador
(figure 11). The signals occurred in swarms and consisted of low-frequency
(1-10 Hz) waves of relatively low-amplitude. Their seismic records were
emergent (i.e. growing in amplitude with time) and of long duration (up to
60 seconds). They are thought to have been possibly associated with rock
falls from lava flowing down the cone's southern flank. As many as 200 of
these events were recorded each day at station CONE.

A return visit to the crater rim on 28 November (this time on foot)
documented abundant fresh lava in the crater (figure 12), a dramatic
increase in the volume of lava there. At least 0.5 x 10^6 m^3 of new lava
then covered the entire crater floor and appeared to be already flowing out
of the southern breach and into the surrounding caldera. Because of cloudy
weather, the exact extent of the flow remained indeterminate. The surface
of this lava flow also extended to the N and reached a level ~20 m below
the northern breach. Continuous lava extrusion or flowing or both were
heard within the crater, making sounds akin to glass breaking, and vigorous
roaring gas emissions originated from the crater's western margin. These
gas emissions and other smaller fumaroles contributed to a plume that was
continuously present, extending at least 1 km above the vent.

Figure 12. Reventador's 2004 lava flow/dome as seen on 28 November 2004.
The photo was taken looking W and downward from the cone's eastern crater
rim (see vantage point indicated by the star on figure 11). Courtesy of IG.

IG observers estimated that the total mid-December lava flow volume was ~3
x 10^6 m^3. The inferred 22 November date of flow onset would imply a
steady-state extrusion rate of ~0.1 x 10^6 m^3 per day and a flow front
advancing at ~80 m per day. These observations appear to conform with
satellite thermal infrared observations, which noted no significant
anomalies until the end of November, due presumably in large part to the
lava being confined within the steep-walled crater. Inclement weather
occurred and also may have impeded some of the satellite thermal observations.

The most recent visit to the crater rim, on 11 December 2004, traced the
source of degassing and lava outflow to the most elevated portion of a
small dome-like feature at the central western margin of the crater. Figure
13 shows how instrumentally aided nighttime incandescence observations
disclosed both the vent area and surficial flow-textures extending S
towards the southern breach of the cone. Figure 14 also documents a
comparatively narrow arm of lava trending towards the cone's northern
breach. Nighttime incandescence from the lava flow was also visible from
local communities such as El Chaco, ~20 km distant.

Figure 13. Thermal image of the lava flow in the interior of Reventador
crater taken with a Forward Looking Infrared (FLIR) imager at 2000 on 11
December 2004. Courtesy of IG.

Figure 14 illustrates the scene on 12 December 2004 during a visit to the
front of the most advanced lobe of lava (for location, see star at end of
flow lobe, figure 9). IG-EPN staff estimated the flow front at ~20 m high
and saw incandescent blocks falling off of it.

Figure 14. A N-looking view of Reventador's gray-colored lava-flow front
taken on 12 December 2004 at ~ 2,600 m elevation. Person at right indicates
scale of the advancing flow front. The lava flow emanated from the breach
in the S side of the cone's crater, a spot seen in the photo's upper left.
Courtesy of IG.

Background. Reventador is the most frequently active of a chain of
Ecuadorian volcanoes in the Cordillera Real, well E of the principal
volcanic axis. The forested dominantly andesitic stratovolcano rises to
3,562 m above the remote jungles of the western Amazon basin. A 4-km-wide
caldera widely breached to the E was formed by edifice collapse and is
partially filled by a young, unvegetated stratovolcano that rises about
1,300 m above the caldera floor to a height above the caldera rim.
Reventador has been the source of numerous lava flows as well as explosive
eruptions that were visible from Quito in historical time. Frequent lahars
in this region of heavy rainfall have constructed a debris plain on the
eastern floor of the caldera. The largest historical eruption at Reventador
took place in 2002, producing a 17-km-high eruption column, pyroclastic
flows that traveled up to 8 km, and lava flows from summit and flank vents.

Information Contacts: Patricio Ramon, Daniel Andrade, David Rivero,
Alexandra Alvarado, Sandro Vaca, and Pete Hall, Geophysical Institute (IG),
Escuela Politecnica Nacional, Apartado 17-01-2759, Quito, Ecuador (URL:
www.igepn.edu.ec/; Email: pramon@igepn.edu.ec;
dandrade@igepn.edu.ec; mhall@igepn.edu.ec); Jeffrey B. Johnson, Dept. of
Earth Sciences, James Hall University of New Hampshire, Durham, NH 03824
(jeff.johnson@unh.edu); MODIS Thermal Alert System, Hawaii Institute of
Geophysics and Planetology (HIGP), School of Ocean and Earth Science and
Technology, University of Hawaii at Manoa (URL:
www.modis.higp.hawaii.edu).


Fuego
Guatemala
14.47°N, 90.88°W; summit elev. 3,763 m
All times are local (= UTC - 6 hours)

Explosions and lava flows at Fuego continued after October 2003 (Bulletin
v. 28, no. 10). Similar activity prevailed through 2003 and 2004. This
report discusses events during November-December 2003 and includes a table
summarizing Fuego's 2003 behavior (table 3). A future report will discuss
2004 activity and will include a map showing critical place names. Several
pyroclastic flows occurred in 2003.

Table 3. Representative examples of reported volcanism at Fuego during
2003. Courtesy of INSIVUMEH.

Date - Lava flows, incandescent avalanches, and
pyroclasticflows (PFs)
- Ash column and ash fall
- Data source(s)

08 Jan 2003 - Lava flows. Two PFs (down Sta. Teresa drainage).
- Steam-and-ash to ~ 5.7 km a.s.l., drifted W.
- INSIVUMEH, CONRED, Washington VAAC, EFE via COMTEX,
Prensa Libra

Mid Jan 2003 - Incandescent avalanches down flanking canyons.
- ~ 2 km above summit, drifting S and SW, depositing
fine ash.
- INSIVUMEH, Washington VAAC

28 Apr-01 May - Incandescent avalanches.
- Intermittent ash eruptions, One ash plume reached ~
7 km a.s.l., blown SW
at 20-30 km/hour; some puffs visible over the coast.
- INSIVUMEH, Washington VAAC; US Air Force Weather Agency

29 Jun 2003 - Lava flows and avalanches down E flank
(incandescence seen from city of
Antigua and the coast). PFs extended ~ 1.5 km down
the W flank.
- Ash fell in villages to W and SE; Ash clouds to ~ 900 m.
- INSIVUMEH

09 Jul 2003 - Lava dome collapse PFs.
- Strong explosions sent ash to ~ 2 km above summit;
ash fell to W and SE
of summit.
- Washington VAAC, Prensa Libre

07 Aug 2003 - N/A
- A small ash emission seen on satellite imagery. The
ash cloud drifted NW
and covered an area about 3.5 by 3.5 km.
- Washington VAAC

08 Sep 2003 - N/A
- Ash plumes; one drifted S and covered an area of 5 x
5 km; another rose
to ~ 6 km a.s.l.
- Washington VAAC

09 Oct 2003 - N/A
- A pilot saw Fuego ash reaching ~ 4.6 a.s.l. No ash
was visible on
satellite imagery.
- Washington VAAC

17 Oct 2003 - Small incandescent avalanche down the Sta. Teresa
valley.
- A 33-minute-long eruption sent a gas-and-ash plume
to ~ 1.5 km above
the crater.
- INSIVUMEH

Nov-Dec 2003 - Incandescent avalanches.
- 4 November explosions threw material 150 m above
crater rim; 18-19
November, gas-and-ash plumes up to 1.2 km above the
crater; 28 Nov-1 Dec,
700-900 m above the crater; 7-9 December, 500 m
above crater; 10-16
December, 200-1000 m above the crater, and 18-22 and
30 December,
'low-level plumes.'
- INSIVUMEH

Tremor was common and at times abundant during 2003, including in the last
two months of the year. On 21 November, almost continuous harmonic tremor
was detected for a span of 21 hours. On 23 November intervals of tremor
lasted between 0.5 and 3 hours.

The Washington VAAC archive contains 48 ash advisories on Fuego. The number
of these advisories were as follows, during the stated months of 2003: 14
advisories in January (on the 8th, 9th, 11th, 12th, and 20th); 11 in April
(on the 17th, 28th, 29th, and 30th); eight in May (1st and 2nd); three in
June (30th), six in July (1st, 9th, and 10th), two in August (7th), two in
September (29th); and two in October (9th). The most impressive plumes
depicted in satellite-based graphics were for 28 April-1 May 2003, when
they often stretched well out to sea, reaching ~160 km SW from Fuego.
Otherwise, the graphics generally depicted much smaller plumes, in some
cases very local ones. The graphic for 28 September showed small plumes
from Fuego as well as simultaneous ones from Pacaya and Santa Maria.

Background. Volcan Fuego, one of Central America's most active volcanoes,
is one of three large stratovolcanoes overlooking Guatemala's former
capital, Antigua. The scarp of an older edifice, Meseta, lies between
3,763-m-high Fuego and its twin volcano to the N, Acatenango. Collapse of
the ancestral Meseta volcano about 8,500 years ago produced the massive
Escuintla debris-avalanche deposit, which extends about 50 km onto the
Pacific coastal plain. Growth of the modern Fuego volcano followed,
continuing the southward migration of volcanism that began at Acatenango.
In contrast to the mostly andesitic Acatenango volcano, eruptions at Fuego
have become more mafic with time, and most historical activity has produced
basaltic rocks. Frequent vigorous historical eruptions have been recorded
at Fuego since the onset of the Spanish era in 1524, and have produced
major ashfalls, along with occasional pyroclastic flows and lava flows.

Information Contacts: Instituto Nacional de Sismologia, Vulcanologia,
Meteorologia e Hidrologia (INSIVUMEH), Unit of Volcanology, Geologic
Department of Investigation and Services, 7a Av. 14-57, Zona 13, Guatemala
City, Guatemala (URL: www.insivumeh.gob.gt/); Washington Volcanic
Ash Advisory Center (VAAC), Satellite Analysis Branch, NOAA/NESDIS E/SP23,
NOAA Science Center Room 401, 5200 Auth Road, Camp Springs, MD 20746 USA
(URL: www.ssd.noaa.gov/); Charles R. Holliday, Air Force Weather
Agency, Offutt Air Force Base, Nebraska 68113 USA; Prensa Libre
(newspaper), 13 calle 9-31 zona 1, 01001 Guatemala City, Guatemala (URL:
www.prensalibre.com/).
__________________________________________________________
Global Volcanism Program, NHB E-421 Tel: (202) 633-1800
Smithsonian Institution Fax: (202) 357-2476
Washington, DC 20560-0119 Email: gvp@si.edu

Internet: www.volcano.si.edu/gvp/
posted by:
Bobs
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  • Re: GVN Bulletin

    Fri, February 11, 2005 - 5:52 AM
    ********************************************************
    Bulletin of the Global Volcanism Network, December 2004
    ********************************************************
    From: Ed Venzke <venzke@volcano.si.edu>


    Bulletin of the Global Volcanism Network
    Volume 29, Number 12, December 2004

    Piton de la Fournaise (Reunion Island) August-October eruption sends lava
    flows to the sea; pillow lavas

    Heard (Indian Ocean) Thermal alerts indicate crater lake activity starting
    in June 2003 until June 2004

    McDonald Islands (Indian Ocean) Thermal anomaly detected on 14 November 2004

    Soputan (Indonesia) Explosive eruption causes ash plume and avalanche on 18
    October 2004

    Canlaon (Philippines) Alert level lowered after seismic decrease; January
    2005 phreatic ash emission

    Mayon (Philippines) Minor activity in June, July, and September 2004;
    reported ash emission

    Taal (Philippines) New episode of seismic unrest began in September 2004

    Anatahan (Mariana Islands) New eruptive episode begins in January 2005; ash
    plumes and dome growth

    Villarrica (Chile) Active lava lake observed during late 2004

    Deception Island (Antarctica) Annual investigations reveal continuing
    seismicity and fumaroles

    Editors: Rick Wunderman, Edward Venzke, and Gari Mayberry
    Volunteer Staff: Robert Andrews, Jacquelyn Gluck, William Henoch, and
    Catherine Galley



    Piton de la Fournaise
    Reunion Island, Indian Ocean
    21.229°S, 55.713°E; summit elev. 2,631 m
    All times are local (= UTC + 4 hours)

    Inflation over the last year and a half, monitored by permanent GPS
    stations, has not been interrupted by six eruptions over this period, the
    latest during 2-18 May 2004 (Bulletin v. 29, no. 5). Increased seismicity
    and ground deformation reported by the Observatoire Volcanologique du Piton
    de la Fournaise (OVPDLF) in late June 2004 continued through 9 August when
    the seismic network recorded 50-70 low-intensity earthquakes. The third
    eruption of 2004 started on 13 August. Increasing seismicity and fissure
    opening had occurred since early July 2004. At 0240 in the morning of 13
    August, a 25-minute seismic crisis beneath the summit preceded the opening
    of an ~500-m-long E-W fissure within Dolomieu crater, with the fissure
    continuing on the E flank to an elevation of 1,900 m. The main activity was
    located at 2,150 m elevation. A significant lava flow ran down the "Grandes
    Pentes."

    Ten days after the beginning of the eruption, ~750 m of National Road 2 was
    overrun, and on 25 August lava from an 8.5-km-long system of lava tubes
    entered the sea. A 670-m-long, 320-m-wide platform was build up within
    several days, representing more than 2 x 10^6 m^3 of material. A second
    smaller platform was build up in the following days by nearby lava flows
    entering the sea. Two small hornitos, up to 8 m high, formed on the seaside
    edge of the first platform. The main eruption phase stopped on 2 September.
    However, significant phreatic activity continued on the new platform and
    was followed by two minor phases from the main vent on the E flank, the
    last one stopping at about 0300 on 4 October. Formation of pillow lava was
    recorded by professional divers for the first time at ile de la Reunion, at
    a water depth of 50 m in front of the new platform.

    The Toulouse Volcanic Ash Advisory Center reported noteworthy eruptive
    activity beginning on 4 September, following the end of the main eruption
    phase. Ash reportedly fell near the volcano's summit, and a lava flow
    entering the sea produced a steam and ash plume that rose ~2 km. Emissions
    ceased on the morning of 7 September.

    Background. The massive Piton de la Fournaise basaltic shield volcano on
    the French island of Reunion in the western Indian Ocean is one of the
    world's most active volcanoes. Much of its >530,000 year history overlapped
    with eruptions of the deeply dissected Piton des Neiges shield volcano to
    the NW. Three calderas formed at about 250,000, 65,000, and less than 5,000
    years ago by progressive eastward slumping of the volcano. Numerous
    pyroclastic cones dot the floor of the calderas and their outer flanks.
    Most historical eruptions have originated from the summit and flanks of
    Dolomieu, a 400-m-high lava shield that has grown within the youngest
    caldera, which is 8 km wide and breached to below sea level on the eastern
    side. More than 150 eruptions, most of which have produced fluid basaltic
    lava flows, have occurred since the 17th century. Only six eruptions, in
    1708, 1774, 1776, 1800, 1977, and 1986, have originated from fissures on
    the outer flanks of the caldera. The Piton de la Fournaise Volcano
    Observatory, one of several operated by the Institut de Physique du Globe
    de Paris, monitors this volcano.

    Information Contacts: Thomas Staudacher, Observatoire Volcanologique du
    Piton de la Fournaise Institut de Physique du Globe de Paris, 97418 La
    Plaine des Cafres, La Reunion, France (URL:
    volcano.ipgp.jussieu.fr:8080/reu...tml; Email:
    Thomas.Staudacher@univ-reunion.fr); Toulouse Volcanic Ash Advisory Center
    (VAAC), Meteo-France, 42 Avenue G. Coriolis, 31057 Toulouse Cedex, France
    (Email: vaac@meteo.fr; URL:
    www.meteo.fr/aeroweb/inf...index.html).


    Heard
    southern Indian Ocean
    53.106°S, 73.513°E; summit elev. 2,745 m

    Infrared satellite data triggered MODVOLC thermal alerts between 24 May
    2000 and 2 February 2001 (Bulletin v. 28, no. 1). A new series of alerts
    began on 9 June 2003, with frequent alerts continuing until 14 June 2004.
    The cloud-free ASTER imagery from June 2003 to June 2004 was examined, and
    although it does not offer very complete coverage of this new phase of
    activity, all the images contained very small anomalies (just a few pixels)
    in the central crater. This suggests that most of these alerts are due to
    increased activity at the lava lake, with no indication of lava flows.
    Also, all the 2003-2004 MODVOLC anomalies were 1-2 pixels (no elongate
    thermal anomalies), further suggesting that this is local central-vent
    activity.

    Background. Heard Island on the Kerguelen Plateau in the southern Indian
    Ocean consists primarily of the emergent portion of two volcanic
    structures. The large glacier-covered composite basaltic-to-trachytic cone
    of Big Ben comprises most of the island, and the smaller Mt. Dixon volcano
    lies at the NW tip of the island across a narrow isthmus. Little is known
    about the structure of Big Ben volcano because of its extensive ice cover.
    The historically active Mawson Peak forms the island's 2745-m high point
    and lies within a 5-6 km wide caldera breached to the SW side of Big Ben.
    Small satellitic scoria cones are mostly located on the northern coast.
    Several subglacial eruptions have been reported in historical time at this
    isolated volcano, but observations are infrequent and additional activity
    may have occurred.

    Information Contacts: Matt Patrick, Luke Flynn, Harold Garbeil, Andy
    Harris, Eric Pilger, Glyn Williams-Jones, and Rob Wright, HIGP Thermal
    Alerts Team, Hawai'i Institute of Geophysics and Planetology (HIGP) /
    School of Ocean and Earth Science and Technology (SOEST), University of
    Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA
    (hotspot.higp.hawaii.edu/, Email: patrick@higp.hawaii.edu).


    McDonald Islands
    southern Indian Ocean
    53.03°S, 72.60°E; summit elev. 186 m

    The first ever MODVOLC thermal anomaly at the McDonald Island volcano was
    detected on 14 November 2004. The anomaly, one pixel in size, was located
    directly over the island. There have been none since then through 13
    January 2005, nor have there been any other obvious false-alert pixels in
    the vicinity, suggesting that this anomaly was genuine.

    Andrew Tupper investigated the above-mentioned anomaly (on a Terra MODIS
    image, overpass time 1827 UTC, 14 November 2004; seen in bands 20-25
    (3.8-4.5 um)). Basically, the anomaly occurred within 2 km of the location
    of the summit coordinates given in the title above. Tupper went on to note:
    "I've looked at other MODIS images from around that time, and some recent
    AVHRR images, but it is extremely difficult to get a cloud-free shot of
    that area. There are no other hot spots visible, and no volcanic plumes
    visible, but unless there was a bonfire lit by a stranded party of
    toothfish poachers at the time, I can't think of any reason to doubt that
    the hot-spot is volcanic."

    Background. Three small, low islands on the Kerguelen Plateau form the
    McDonald Islands. The largest island, McDonald, is composed of a layered
    phonolitic tuff plateau cut by phonolitic dikes and lava domes. A possible
    nearby active submarine center was inferred from phonolitic pumice that
    washed up on Heard Island in 1992. Volcanic plumes were observed in
    December 1996 and January 1997 from McDonald Island. During March of 1997
    the crew of a vessel that sailed near the island noted vigorous steaming
    from a vent at the N side of the island along with possible pyroclastic
    deposits and lava flows. During a visit to the area in November 2002 the
    island was reported to have more than doubled in area since previous
    reported observations in November 2000. The high point of the island group
    had shifted to the N end of MacDonald island, which had merged with Flat
    Island to the north.

    Information Contacts: Matt Patrick, Luke Flynn, Harold Garbeil, Andy
    Harris, Eric Pilger, Glyn Williams-Jones, and Rob Wright, HIGP Thermal
    Alerts Team, Hawai'i Institute of Geophysics and Planetology (HIGP) /
    School of Ocean and Earth Science and Technology (SOEST), University of
    Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA
    (hotspot.higp.hawaii.edu/, Email: patrick@higp.hawaii.edu); Andrew
    Tupper, Darwin Volcanic Ash Advisory Centre (VAAC), Commonwealth Bureau of
    Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina,
    NT 0811, Australia (URL: www.bom. gov.au/info/vaac/; Email:
    darwin.vaac@bom.gov.au).


    Soputan
    Sulawesi, Indonesia
    1.108°N,124.725°E; summit elev. 1,784 m
    All times are local (= UTC + 8 hours)

    Activity at Soputan that began on 18 July 2003 (Bulletin v. 28, no. 8)
    continued with occasional ash explosions in August (Bulletin v. 28, nos.
    10-11) and through 4 September 2003 (Bulletin v. 29, no. 11). The report of
    the 12 December 2004 eruption (Bulletin v. 29, no. 11) also mentioned
    activity on 18 October. The following information from the Indonesian
    Directorate of Volcanology and Geological Hazard Mitigation describes that
    October 2004 activity in greater detail.

    Volcanic tremor increased at 0930 on 18 October 2004 with amplitudes in the
    range of 10-40 mm. From 1026 to 1452 tremor amplitudes reached a maximum of
    41 mm (over scale). At 1041 Soputan exploded, releasing a white to gray ash
    column as high as 600 m above the crater rim and drifting E. The explosion,
    along with rumbling sounds, was heard at the Post Observatory ~12 km from
    the summit. Based on increasing seismicity, the official hazard level was
    raised to Orange or II (on a scale of I-IV) at 1500 that day. At 1815
    incandescence was visible, rising 25-30 m above the crater rim. Ash reached
    the Observatory at 2130, and a "lava avalanche" at 2135 traveled to the S.
    Tremor was recorded until 0712 on the following day, 19 October, with
    amplitudes of 0.5-2 mm.

    A GOES-9 satellite loop of the 18 October 2004 eruption was compiled by the
    Darwin Volcanic Ash Advisory Centre (VAAC). Based on the dispersion
    patterns and infrared temperatures (minimum temperature of zero degrees),
    the cloud probably reached between 5,000 and 6,000 m altitude, where there
    was an atmospheric inversion that prevented further rise.

    The Darwin VAAC also noted that a satellite image from the Terra MODIS
    instrument taken at 0210 UTC on 1 September 2003 showed an eruption plume
    during clear weather. The imaged eruption, described as a low-level cloud
    streaming to the SW that probably didn't rise much above the summit,
    occurred during a period of previously reported ash plumes and lava flow
    activity (Bulletin v. 28, no. 10).

    Background. The small Soputan stratovolcano on the southern rim of the
    Quaternary Tondano caldera on the northern arm of Sulawesi Island is one of
    Sulawesi's most active volcanoes. The youthful, largely unvegetated volcano
    rises to 1784 m and is located SW of Sempu volcano. It was constructed at
    the southern end of a SSW-NNE trending line of vents. During historical
    time the locus of eruptions has included both the summit crater and
    Aeseput, a prominent NE-flank vent that formed in 1906 and was the source
    of intermittent major lava flows until 1924.

    Information Contacts: Directorate of Volcanology and Geological Hazard
    Mitigation, Jalan Diponegoro 57, Bandung 40122, Indonesia (Email:
    dali@vsi.dpe.go.id; URL: www.vsi.esdm.go.id/); Andrew Tupper, Darwin
    Volcanic Ash Advisory Centre (VAAC), Australian Bureau of Meteorology (URL:
    www.bom.gov.au/info/vaac/soputan.shtml).


    Canlaon
    central Philippines
    10.412°N, 123.132°E; summit elev. 2,435 m

    The Philippine Institute of Volcanology and Seismology (PHIVOLCS) noted in
    a March 2004 report that the most recent eruptive episode of Canlaon had
    begun on 7 March 2003. Their 2003 Annual Report described a mild
    ash-and-steam emission on 7 March that rose 1 km above the summit and
    resulted in traces of ash deposited at Cabagnaan, 5.5 km S. On 17 March
    2003 the hazard status had been raised to Alert Level 1 (Bulletin v. 28,
    nos. 3, 6, 7, and 8). A total of 46 minor ash ejections were documented or
    observed, most from June to July 2003, characterized by steam clouds with
    minor ash that rose as high as 1,500 m. Prevailing winds dispersed the ash
    over the mid-upper slopes in the SW and SE sectors of the volcano.

    Sporadic recordings of high-frequency volcanic earthquakes (HFVQ) and
    low-frequency volcanic earthquake swarms (LFVQ) starting in January 2003
    prompted PHIVOLCS to issue a warning on the possibility of sudden phreatic
    explosions. In June 2003 daily occurrences of LFVQs increased dramatically
    and these heightened levels were sustained until July 2003. Low-frequency
    short-duration harmonic tremors (SDHLF) also appeared in June 2003 and
    increased like the LFVQs, indicating a continuous supply and transport of
    volcanic fluids towards the shallow levels of the crater area.

    A general trend towards volcanic quiet was recognized during August 2003,
    but the status was maintained at Alert Level 1 because HFVQs, LFVQs, and
    SDHLFs persisted, though in diminishing numbers, until September 2003.
    After that time, steam emissions from the summit crater were only weak or
    absent, with normal levels of seismic activity. On 1 March 2004 PHIVOLCS
    lowered the hazard status to Alert Level 0, meaning the volcano has
    returned to a quiet state. The public was strongly advised, however, to
    consider the risk when entering the 4-km Permanent Danger Zone because
    sudden phreatic explosions may occur without warning. People planning to
    climb the volcano are advised to check with an observatory first.

    Phreatic emission, January 2005. The value of continued warnings was shown
    on 21 January 2005, when Canlaon generated a sudden brief ash emission. The
    PHIVOLCS observatory at La Carlota City College reported moderate emission
    of a grayish volcanic plume at about 0930 that rose to ~500 m above the
    active crater and drifted WNW and SW, depositing light ash on the upper SW
    slopes. Traces of ash deposits were also observed at Cabagnaan, 5.5 km SW
    of the active crater. No coincident volcanic earthquakes were recorded, and
    Canlaon continued to be seismically quiet. These observations suggest the
    activity is hydrothermal in nature and occurring at very shallow levels
    near the crater floor.

    Background. Canlaon volcano (also spelled Kanlaon), the most active of the
    central Philippines, forms the highest point on the island of Negros. The
    massive 2435-m-high stratovolcano is dotted with fissure-controlled
    pyroclastic cones and craters, many of which are filled by lakes. The
    summit of Canlaon contains a broad elongated northern caldera with a crater
    lake and a smaller, but higher, historically active crater to the south.
    The largest debris avalanche known in the Philippines traveled 33 km to the
    SW from Canlaon. Historical eruptions, recorded since 1866, have typically
    consisted of phreatic explosions of small-to-moderate size that produce
    minor ashfalls near the volcano.

    Information Contact: Philippine Institute of Volcanology and Seismology
    (PHIVOLCS), Department of Science and Technology, PHIVOLCS Building, C.P.
    Garcia Avenue, Univ. of the Philippines Campus, Diliman, Quezon City,
    Philippines (URL: www.phivolcs.dost.gov.ph/).


    Mayon
    Luzon, Philippines
    13.257°N, 123.685°E; summit elev. 2,462 m

    An explosion-type volcanic earthquake detected by the Upper Anoling seismic
    station on the afternoon of 3 June 2004 was not visually observed due to
    thick clouds covering the summit. Residents closer to the Upper Anoling
    Seismic Station and Mayon Resthouse did not notice any unusual activity. No
    traces of ash or changes in the crater wall were observed. Sulfur dioxide
    (SO2) emission rose from 1,169 metric tons/day (t/d) on 12 May to 2,521 t/d
    on 4 June, then decreased to 1,514 t/d on 18 June. Precise leveling
    measurements showed a slight but deflation of the edifice. The number of
    low-frequency volcanic earthquakes and low-frequency short-duration
    harmonic tremors increased in June to almost twice the number recorded in
    May. In addition, faint crater glow continued to be observed at the summit,
    as it had since 7 October 2003.

    Another explosion was recorded on 22 July 2004. According to news reports,
    ash from that event was deposited in two local villages.

    Sulfur dioxide (SO2) emissions remained only slightly above baseline at
    829 metric tons per day as of 6 September 2004. On the evening of 12
    September 2004 the very faint glow at the summit of Mayon intensified
    slightly. The brighter incandescence, observable from Lignon Hill Volcano
    Observatory and in Legaspi City proper, coincided with a slight increase in
    the overall background tremor detected by seismographs around the volcano.
    However, there were no significant changes in ground deformation or SO2
    measurements. A news report also noted that volcanic material emitted from
    the crater that day set fire to grass on the volcano's slopes.

    The hazard status remained at Alert Level 2, indicating a low level of
    volcanism. PHIVOLCS reminded the public to refrain from venturing into the
    6-km Permanent Danger Zone because life-threatening volcanic flows may
    occur with little or no warning.

    Background. Beautifully symmetrical Mayon volcano, which rises to 2462 m
    above the Albay Gulf, is the Philippines' most active volcano. The
    structurally simple volcano has steep upper slopes averaging 35-40 degrees
    that are capped by a small summit crater. The historical eruptions of this
    basaltic-andesitic volcano date back to 1616 and range from strombolian to
    basaltic plinian, with cyclical activity beginning with basaltic eruptions,
    followed by longer term andesitic lava flows. Eruptions occur predominately
    from the central conduit and have also produced lava flows that travel far
    down the flanks. Pyroclastic flows and mudflows have commonly swept down
    many of the approximately 40 ravines that radiate from the summit and have
    often devastated populated lowland areas. Mayon's most violent eruption, in
    1814, killed more than 1200 people and devastated several towns.

    Information Contact: Philippine Institute of Volcanology and Seismology
    (PHIVOLCS), Department of Science and Technology, PHIVOLCS Building, C.P.
    Garcia Avenue, Univ. of the Philippines Campus, Diliman, Quezon City,
    Philippines (URL: www.phivolcs.dost.gov.ph/); Associated Press (URL:
    www.ap.org/); The Australian (www.theaustralian.news.com.au/).


    Taal
    Luzon, Philippines
    14.002°N, 120.993°E; summit elev. 400 m

    The Taal seismic monitoring network began to record significant volcanic
    earthquakes on 23 September 2004. In general, the numbers of these events
    occurring through 29 October increased, with a maximum 13 earthquakes on 15
    October. Some of these earthquakes were instrumentally recorded with
    relatively large amplitudes although none were felt by residents on Volcano
    Island. Initial earthquake locations showed epicenters dispersed in the
    vicinity of Main Crater, to the NNW near Binintiang Malaki, and to the SSE
    near Calauit. Surface observations, however, did not indicate any
    significant change in the thermal and steam emission characteristics of the
    Main Crater lake area. The increased seismicity is an indication of a
    low-level episode of unrest, although at this time there is no clear
    indication of an impending eruption. A series of volcanic earthquakes was
    recorded on 9 January 2005. Two of these earthquakes, only one minute
    apart, were felt in Pira-piraso.

    PHIVOLCS raised the hazard status on 29 October from Alert Level 0 to Alert
    Level 1, meaning that there was a slight increase in seismic activity but
    no eruption is imminent. PHIVOLCS recommend as off-limits the Main Crater
    area because sudden steam explosions may occur or high concentrations of
    noxious gases may accumulate. Several fissures traversing the Daang Kastila
    Trail are also potentially hazardous as possible sites of future steam
    emission. PHIVOLCS is conducting several enhancements of the monitoring
    system at Taal with deployment of more seismometers and ground-deformation
    surveillance equipment. The entire Volcano Island is a Permanent Danger
    Zone and permanent settlement is strictly prohibited.

    Background. Taal volcano is one of the most active volcanoes in the
    Philippines and has produced some of its most powerful historical
    eruptions. In contrast to Mayon volcano, Taal is not topographically
    prominent, but its prehistorical eruptions have greatly changed the
    topography of SW Luzon. The 15 x 20 km Taal caldera is largely filled by
    Lake Taal, whose 267 sq km surface lies 700 m below the south caldera rim
    and only 3 m above sea level. The maximum depth of the lake is 160 m, and
    several eruptive centers lie submerged beneath the lake. The 5-km-wide
    Volcano Island in north-central Lake Taal is the location of all historical
    eruptions. The island is a complex volcano composed of coalescing small
    stratovolcanoes, tuff rings, and scoria cones that has grown about 25% in
    area during historical time. Powerful pyroclastic flows and surges from
    historical eruptions of Taal have caused many fatalities.

    Information Contact: Philippine Institute of Volcanology and Seismology
    (PHIVOLCS), Department of Science and Technology, PHIVOLCS Building, C.P.
    Garcia Avenue, Univ. of the Philippines Campus, Diliman, Quezon City,
    Philippines (URL: www.phivolcs.dost.gov.ph/).


    Anatahan
    Mariana Islands, central Pacific Ocean
    16.35°N, 145.67°E; summit elev. 788 m
    All times are local (= UTC + 10 hours)

    Although the latest eruptive period ended in late July (Bulletin v. 29, no.
    8), the volcanic system at Anatahan continued to exhibit unrest in the
    following months. On 27 September, several hours after the onset of a
    series of intense tropical depressions and storms, the first long-period
    seismic events since July 2004 were recorded. However, only a few, small
    events occurred. Beginning on 12 October, several episodes of small,
    regularly-spaced long-period events were recorded at intervals of 4-15
    seconds. On 18 October, people in Saipan smelled H2S during very hazy
    visibility, but no plume was detected on satellite imagery by the
    Washington Volcanic Ash Advisory Center (VAAC).

    Based on a pilot report to the Guam Forecast Office, the Washington VAAC
    reported that ash from Anatahan was at a height of ~3 km altitude on 2
    December. Ash was not visible on satellite imagery, but a hotspot was
    briefly evident on infrared imagery.

    Eruptions in January 2005. Major eruptive activity at Anatahan resumed on 5
    January 2005, preceded by two days of small long-period earthquakes and a
    day of harmonic tremor. The airport tower at Guam confirmed that a plume of
    diffuse ash and gas up to ~200 m above the vent was visible at first light
    on 6 January, and at the 1225 hours VAAC reported a plume 60 km long and 20
    km wide, blowing W.

    Frequent Strombolian explosion signals began on 6 January and continued
    during 7 and 8 January, accompanied by a change in the seismic signals,
    from harmonic tremor to a broader band tremor, with explosions recorded by
    microphones several times per minute. The eruption type and activity level
    were both very similar to the peak eruptive activity during the eruption of
    April-June 2004 (Bulletin v. 29, nos. 4, 5, and 6). During an overflight on
    7 January, personnel from the Emergency Management Office (EMO) reported
    ash rising well above 1,500 m and a plume that likely extended up to 100 km
    downwind. A dome was visible in the crater and bombs were observed rising
    less than 600 m.

    On 7 January ash rose to ~3 km and bombs a meter or more in diameter were
    expelled to ~100 m and formed a new cinder cone ~120 m in diameter. The
    amplitude of the explosion signals increased slowly after 6 January to
    about double these values by noon on 10 January, with explosions every 3-10
    seconds. Explosion signals amplitudes then plunged suddenly to half the
    values at the start of 10 January. The amplitudes surged again, nearly
    doubling by approximately 0400 on 11 January, dropping to half the value
    again by about noon. The eruption apparently stabilized at that level
    through 14 January. During 15-19 January, the eruption appears to have
    stopped twice for a few hours but swiftly resumed at higher levels.
    National Oceanic and Atmospheric Agency (NOAA) satellite photos show a
    plume of vog (volcanic smog) trailing ~60 km downwind.

    Near mid-day on 20 January seismicity dropped abruptly to near background
    levels, whereas microphone noise became fairly continuous, indicating that
    the explosions had ceased but that degassing may have been continuing. The
    apparent cessation of Strombolian activity lasted until late 22 January,
    when explosions resumed. The eruption peaked about 0700 on 23 January, at
    which time a SIGMET (significant meteorological forecast) was issued by the
    FSS (Flight Service Station) Honolulu, based on pilot reports of ash up to
    3-4.6 m. The explosions then decreased somewhat but were still frequent and
    strong through 24 January, based on the seismicity.

    The EMO placed Anatahan Island off limits until further notice and
    concluded that, although the volcano was not currently dangerous to most
    aircraft within the CNMI airspace, conditions may change rapidly. Aircraft
    should pass upwind of, or beyond 30 km downwind from, the island, and
    exercise due caution within 30 km of Anatahan.

    Synopsis of recent eruptions. Anatahan had no historical eruptions prior to
    2003. On 10 May of that year, after several hours of increasing seismicity,
    a phreatomagmatic eruption sent ash to over 10 km and deposited about 10
    million cubic meters of material over the island and sea. A very small
    craggy dome extruded during late May and was destroyed during explosions on
    14 June, after which the eruption essentially ceased. A second eruption
    began about 9 April 2004, after more than a week of increasing seismicity.
    The eruption consisted of passive extrusion during mid-April, then
    increased to Strombolian explosions every minute or two on 24 April. The
    Strombolian explosions continued through mid-July, often sending a thin
    plume of gas and ash upwards a few hundreds of meters and 100 km downwind.
    Activity decreased substantially on 26 July, though visitors to the island
    three months later could still see very small amounts of steam and ash
    rising 30-40 m above the crater rim and could smell SO2 near the crater.

    Background. The elongated, 9-km-long island of Anatahan in the central
    Mariana Islands consists of two coalescing volcanoes with a 2.3 x 5 km,
    E-W-trending summit depression formed by overlapping summit calderas. The
    larger western caldera is 2.3 x 3 km wide and extends eastward from the
    summit of the western volcano, the island's 788-m high point. Ponded lava
    flows overlain by pyroclastic deposits fill the caldera floor, whose SW
    side is cut by a fresh-looking smaller crater. The summit of the lower
    eastern cone is cut by a 2-km-wide caldera with a steep-walled inner crater
    whose floor is only 68 m above sea level. Sparseness of vegetation on the
    most recent lava flows on Anatahan indicated that they were of Holocene
    age, but the first historical eruption of Anatahan did not occur until May
    2003, when a large explosive eruption took place forming a new crater
    inside the eastern caldera.

    Information Contacts: Juan Takai Camacho and Ramon Chong, Emergency
    Management Office of the Commonwealth of the Northern Mariana Islands
    (CNMI/EMO), P.O. Box 100007, Saipan, MP 96950, USA (URL:
    www.cnmiemo.org/; Email: juantcamacho@hotmail.com and
    rcchongemo@hotmail.com); Frank Trusdell, Hawaii Volcano Observatory, U.S.
    Geological Survey (HVO/USGS), Hawaii National Park, HI 96718, USA (URL:
    hvo.wr.usgs.gov/cnmi/; Email: trusdell@usgs.gov); Washington
    Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch, NOAA/NESDIS
    E/SP23, NOAA Science Center Room 401, 5200 Auth Road, Camp Springs, MD
    20746 USA (URL: www.ssd.noaa.gov/); NOAA/ National Weather Service,
    National Centers for Environmental Prediction, Aviation Weather Center,
    Volcanic Ash SIGMETS, (URL:adds.aviationweather.gov/airmets/)


    Villarrica
    central Chile
    39.42°S, 71.93°W; summit elev. 2,847 m
    All times are local (= UTC - 4 hours, -3 hours October-March)

    The last report of activity at Villarrica, through May 2002 (Bulletin v.
    27, no. 6), described a general decrease in incandescence in the summit
    crater's lava lake, and noted ballistics ejected in January 2002.

    Jacques-Marie Bardintzeff reported that climbers to the top of the volcano
    on 5 November 2004 noted a strong sulfur smell and observed projections of
    red lava at a depth of 200-300 m in the crater. On 16 November, a small
    lava lake was visible in the crater from the air; it was photographed on
    the 19th (figure 1). Many volcanologists attending the IAVCEI General
    Assembly at Pucon 14-19 November 2004 ascended and observed activity in the
    summit crater (figure 2). Although the lava lake itself lay at the bottom
    of a steep-walled inner crater and was not visible, periodic ejection of
    large quantities of incandescent lava fragments to a maximum height just
    above the rim of the inner crater could be seen from a bench below the SW
    rim of the outer summit crater (figure 3). Bardintzeff noted on 24 November
    2004 that a white and blue plume of H2O vapor and SO2, extending to the E
    from Villarrica, was observed from Pucon. During the night, the plume was
    red colored. According to the local inhabitants, this was the first
    observation of a plume since January 2004.

    Figure 1. A near-vertical aerial view into the ~ 250-m-wide summit crater
    of Villarrica volcano at about 1430 on 19 November shows the incandescent
    lava lake in the steep-walled inner crater. The chain of dots left (north)
    of the crater are climbers ascending to the crater rim. The photograph was
    taken through the side window of a Cessna aircraft executing an extremely
    sharp turn. Figure 2 (below) was taken from the upper left crater rim and
    figure 3 from the lower right. Courtesy of Jean-Claude Tanguy.

    Figure 2. Climbers walk along the outer snow-covered rim of Villarrica's
    summit crater on 17 November 2004 and stand on a small bench just below the
    SW rim (left), which provided periodic views of incandescent ejecta from
    the inner crater lava lake (figure 3). Courtesy of Judy Harden.

    Figure 3. Incandescent spatter and bombs are ejected from the lava lake in
    the inner crater of Villarrica as seen from a bench just below the SW rim
    of the outer crater on 17 November 2004. Courtesy of Judy Harden.

    According to the Publicacion Oficial del Grupo Projecto de Observacion
    Villarrica (P.O.V.I.) website, incandescence was seen above the summit
    crater on the nights of 5-6 August and 27-28 October 2004 and frequently
    during November and December. On the night of 12-13 December Strombolian
    explosions every 2-5 minutes ejected incandescent spatter and bombs to 100
    m height that landed on the outer crater rim. On the 13th the lava lake was
    ~30 m in diameter and at a depth of ~100 m. Vigorous convection of the lava
    lake was punctuated at intervals not exceeding 15 seconds by Strombolian
    explosions that ejected fine ash, lapilli up to 4 mm in diameter that fell
    to within a few meters of the inner edge of the crater, and incandescent
    spatter to the NE to heights of ~50 m. By 27 December solidification of
    ejected spatter around the vent had decreased its diameter by 2/3 with
    respect to 13 December, and Strombolian explosions at intervals of 2-5
    minutes ejected material ~100 m above the vent. On 9 and 17 January minor
    explosions took place at intervals of 1-2 minutes. By 17 January fissures
    had formed around the N to E sides of the vent, and the opposite side of
    the vent edge, and the slope above it, had collapsed.

    Satellite-based MODIS thermal alerts were first detected at 0345 UTC on 5
    November and also occurred on 6, 16, 17, 22, 24, and 29 November, 5, 8, 9,
    14, 19, 21, and 31 December, and 1 and 2 January 2005. Prior to 5 November
    2004, MODIS thermal alerts not previously reported in this Bulletin had
    been detected at Villarrica on 23 May, 10 and 17 July, 2, 6, 25, and 27
    August, 16 and 28 September, 2, 12, 14, 27, and 30 October, 1, 3, 22, and
    28 November 2003, 31 January, 1-3, 7, 10, 12, and 14 February, and 0345 UTC
    on 26 March 2004 (2345 local time 25 March). According to the P.O.V.I.
    website, strong explosive activity ejected incandescent pyroclastic
    material on 28 August 2003, and except for three cloud-covered days,
    incandescence above the summit crater was seen daily from 27 January to 20
    February 2004.

    Background. Villarrica, one of Chile's most active volcanoes, rises above
    the lake and town of the same name. It is the westernmost of three large
    stratovolcanoes that trend perpendicular to the Andean chain. A 6-km wide
    caldera formed during the late Pleistocene. A 2-km-wide caldera that formed
    about 3,500 years ago is located at the base of the presently active,
    dominantly basaltic to basaltic-andesitic cone at the NW margin of the
    Pleistocene caldera. More than 30 scoria cones and fissure vents dot
    Villarrica's flanks. Plinian eruptions and pyroclastic flows that have
    extended up to 20 km from the volcano have been produced during the
    Holocene. Lava flows up to 18 km long have issued from summit and flanks
    vent. Historical eruptions, documented since 1558, have consisted largely
    of mild-to-moderate explosive activity with occasional lava effusion.
    Glaciers cover 40 km^2 of the volcano, and lahars have damaged towns on its
    flanks.
    General Reference. Calder, E.S., Harris, A.J.L., Pena, P., Pilger, E.,
    Flynn, L.P., Fuentealba, G., and Moreno, H., 2004, Conbined thermal and
    seismic analysis of the Villarrica volcano lava lake, Chile: Revista
    Geologica de Chile, v. 31, no. 2, p. 259-272.

    Lara, L.E., and Clavero, J. (eds.), 2004, Villarrica volcano (39.5°S),
    Southern Andes, Chile: Servicio Nacional de Geologia y Mineria - Chile,
    Santiago, Boletin No. 61.

    Information Contacts: Jacques-Marie Bardintzeff, Laboratoire de
    Petrographie- Volcanologie, Bât. 504 Universite Paris-Sud, F-91405 Orsay,
    France (URL: www.lave-volcans.com/bardintzeff.html, Email:
    bardizef@geol.u-psud.fr); Judy Harden, Department of Geology, University of
    South Florida, 4202 E. Fowler Ave, SCA528, Tampa, FL 33620, USA (Email:
    jaharden@juno.com); Publicacion Oficial del Grupo Projecto de Observacion
    Villarrica - Internet (P.O.V.I.) (URL: www.povi.cl/); Jean-Claude
    Tanguy, Univ. Paris 6 & Institut de Physique du Globe de Paris,
    Observatoire de St. Maur, 94107 St. Maur des Fosses, France (Email:
    tanguy@ipgp.jussieu.fr).


    Deception Island
    South Shetland Islands, Antarctica
    62.97°S, 60.65°W; summit elev. 576 m

    Deception Island is the most active volcano in the Antarctic Peninsula
    region. A team of Spanish-Argentine scientists collected data from 25
    November 2003 to 16 March 2004 in order to provide background activity
    records. Local and regional seismicity, thermal activity, gas emission,
    geodetic, and geological studies were carried out. During this survey, one
    seismic antenna and three continuous-recording stations were installed
    (figure 4). One dense seismic antenna with twelve vertical-component
    short-period seismometers was located between the Spanish and Argentine
    base stations, one vertical-component short-period seismometer was placed
    at North Fumarole Bay (with telemetry), and three-component short-period
    seismic stations were installed near both the "Gabriel de Castilla" Spanish
    station and the Argentine station.

    Figure 4. Seismological stations deployed at Deception Island in 2003-2004
    summer survey. Courtesy of the Spanish-Argentine research team.

    The recorded seismicity included long-period events (LP), volcanic-tremor
    episodes (T), and a few volcano-tectonic earthquakes (VT). More than 3,660
    LP events events were recorded (figure 5), 35 of them with hybrid
    character, and many with frequencies of 1-8 Hz. Eight volcanic tremors
    occurred with durations ranging from less than one hour to twenty-one
    hours; 66 VT earthquakes were also recorded. Four remarkable periods of
    activity were detected in this survey, during last December, mid-January,
    early February, and mid-March. All of these periods were characterized by a
    relatively high level of seismic activity with frequent LP events and
    tremor. Most earthquakes recorded during the field season were located
    inside the island, and these events have been closely related with LP and
    tremor events. Earthquakes with S-P wave time lags of less than 3 seconds
    were classified as local or VT, with local magnitudes of up to 2.0, none of
    which were felt. LP seismicity might be related to thaw water (seasonal
    effect) but this year's anomalous activity could also be due to strong
    pressurization in a sealed system.

    Figure 5. Long-period seismic activity at Deception Island during the
    2003-2004 summer survey. Adapted from a histogram showing six types of
    recorded seismicity. Courtesy of the Spanish-Argentine research team.

    Fumarole temperatures and hot soils remained stable between 99 and 101ºC in
    Fumarole Bay, 95ºC in Caliente hill, 65ºC in Whalers Bay, 41ºC in Telefon
    Bay, and 72ºC in Pendulum Cove. Systematic monitoring of fumarolic activity
    continued as in past years, and during this survey radon was measured.
    Samples of condensable and uncondensable acid gases were collected. The
    obtained composition from the fumarole vents at Fumarole Bay was similar to
    previous years. The average chemical composition of the fumarolic gases was
    H2O(v) (86.21%), CO2 (13.59%), H2S (0.19%), and SO2 (0.01%). Lapilli with a
    coating of pyrite were found around vent outlets. Compositional changes in
    acidic gases observed in early February and March 2004 correlated with
    increased seismicity, especially with LP events.

    Background. Ring-shaped Deception Island, one of Antarctica's most well
    known volcanoes, contains a 7-km-wide caldera flooded by the sea. Deception
    Island is located at the SW end of the Shetland Islands, NE of Graham Land
    Peninsula, and was constructed along the axis of the Bransfield Rift
    spreading center. A narrow passageway named Neptunes Bellows provides
    entrance to a natural harbor that was utilized as an Antarctic whaling
    station. Numerous vents located along ring fractures circling the low,
    14-km-wide island have been active during historical time. Maars line the
    shores of 190-m-deep Port Foster, the caldera bay. Among the largest of
    these maars is 1-km-wide Whalers Bay, at the entrance to the harbor.
    Eruptions from Deception Island during the past 8700 years have been dated
    from ash layers in lake sediments on the Antarctic Peninsula and
    neighboring islands.

    Information Contacts: A.T.Caselli, C. Bengoa, and E. Rojas Vera,
    Universidad de Buenos Aires-Instituto Antartico Argentino, Ciudad
    Universitaria, Pab.2, (1428) Buenos Aires, Argentina (Email:
    acaselli@gl.fcen.uba.ar); A. Bidone and G. Badi, Dpto. de Sismologia e
    I.M., Facultad de Cs. Astronom. y Geofisicas, UNLP, Av. Centenario s/n
    Paseo del Bosque, B1900FWA La Plata, Pcia. de Buenos Aires, Argentina;
    Daria Zandomeneghi, Nieves Sanchez, Fermin Fernandez-Ibanez, and Jesus
    Ibanez, Instituto Andaluz de Geofisica y P.D.S. Universidad de Granada,
    Campus Universitario de Cartuja, s/n 18071, Granada, Spain.
    __________________________________________________________
    Global Volcanism Program, NHB E-421 Tel: (202) 633-1800
    Smithsonian Institution Fax: (202) 357-2476
    Washington, DC 20560-0119 Email: gvp@si.edu

    Internet: www.volcano.si.edu/
  • Re: GVN Bulletin

    Sat, March 12, 2005 - 9:21 AM
    *******************************************************
    Bulletin of the Global Volcanism Network, January 2005
    *******************************************************
    From: Ed Venzke <venzke@volcano.si.edu>


    Bulletin of the Global Volcanism Network
    Volume 30, Number 1, January 2005


    Asama (Japan) 1 September 2004 eruption followed by others at least as late
    as 14 November

    Raung (Indonesia) MODIS-MODVOLC infrared hot spots 3 June-8 Oct 2004;
    aerial photos from 2001

    Kerinci (Indonesia) 27 September 2004 ash plumes to 6 km altitude; thick
    gray plumes during October 2004

    Marapi (Indonesia) Small eruptions and seismicity during August to October 2004

    Etna (Italy) 7 September eruption continues on W wall of Valle del Bove,
    includes lava tubes, multiple vents

    Erta Ale (Ethiopia) Hornitos on chilled lava lake surface in January 2005;
    December 2004 glass analyses

    Popocatepetl (Mexico) Relative quiet of 2004 ended during December 2004 and
    January 2005

    Colima (Mexico) Block-lava escapes starting in September 2004 getting well
    down N flank by October


    Editors: Rick Wunderman, Edward Venzke, and Gari Mayberry
    Volunteer Staff: Robert Andrews, Jacquelyn Gluck, William Henoch, and
    Catherine Galley



    Asama
    Honshu, Japan
    36.40°N, 138.53°E; summit elev. 2,560 m
    All times are local (= UTC + 9 hours)

    At 2020 on 1 September 2004, an explosive eruption occurred from the summit
    crater of Asama (Bulletin v. 29, nos. 8 and 10). As previously reported,
    the resulting eruption cloud drifted NE, and ash fell ~250 km away. A
    Reuters news report stated that this was its biggest eruption in 21 years
    (since April 1983). A distinct plume was still discharging on 3 September,
    when Asia Air Surveys took a vertical aerial photograph (figures 1 and 2).

    Figure 1. Topographic map showing the flight lines and locations of aerial
    photos at Asama volcano (N is towards the top), 3 September 2004. Courtesy
    of Asia Air Survey Co., Ltd.

    Figure 2. Aerial photo of Asama taken on 3 September 2004; the shot was
    taken at the point labeled "90" on line C3 on figure 1, in effect, from a
    point slightly E of the summit crater. Copyrighted photo is used here with
    permission of Asia Air Survey Co., Ltd. (their photo number C3-9590).

    Setsuya Nakada and Yukio Hayakawa informed Bulletin editors of Asama's
    eruptions by preparing reports and outlines in English, or explaining the
    significance of several kinds of data that were not otherwise accessible in
    English. Investigators plan to present data on Asama's 2004 eruptions at
    upcoming conferences, including The Joint Geoscience Meeting, to be held in
    May 2005 at Makuhari, Chiba (Japan).

    A small eruption around 1530 on 14 September (figure 3) produced an ash
    plume that rose 1-2.5 km above the volcano. A smaller eruption earlier that
    day around 0328 produced a plume that rose ~300 m. A small amount of ash
    fell in Takasaki, ~45 km from the volcano.

    Figure 3. A drifting eruption cloud emitted at Asama, as seen from the
    Geological Society of Japan office building in Tsukuba, ~150 km E of the
    volcano. Taken at 1751 on 14 September. Courtesy of A. Tomiya, GSJ.

    Asama erupted almost continuously for a third straight day on 16 September
    (figure 4), associated with more than 1,000 earthquakes. Incandescent
    fragments were ejected ~300 m from the summit and ash columns rose ~1,200 m
    above the crater. Late that night, winds carried ash as far as central
    Tokyo, ~140 km SE. The frequency of the eruptions appeared to have tapered
    off by the afternoon of the 17th. Television footage at that time showed
    gray smoke mixed with ash billowing over the mountain. Minor ash eruptions
    occurred intermittently until 2103 on 18 September; ash clouds drifted E.
    Ashfall covered the southern part of the Kanto area, more than 150 km from
    the volcano.

    Figure 4. A panoramic photograph of Asama taken 16 September 2004 looking
    from Asama's NE flank. Courtesy of Michiko Owada, GSJ.

    By 18 September, the Japan Meteorological Agency (JMA) was reporting that
    ash plumes were still rising ~1,200 m, but only about 23 small eruptions
    and nearly 140 tremors had been recorded that afternoon, a significant
    change from the nearly continuous activity of the previous few days. The
    hazard status remained at 3 on a scale of 5, suggesting more
    small-to-medium eruptions might occur.

    An analysis of crater morphology based on airborne radar conducted on 16
    September confirmed a new lava dome there. According to JMA and the
    Geographical Survey Institute this was the first dome since 1973.
    Mid-September radar images showed the growth of a broad (pancake-shaped)
    layered form reaching several dozen meters high with a radius of ~100 m in
    the NE part of the crater; its volume was ~500,000 m^3. Compelling images
    showcasing the side-looking airborne (SAR) radar method and depicting the
    dome can be seen on the GSI website (but as of early 2005 almost all the
    text remained in Japanese).

    A moderate explosive eruption occurred at 1944 on 23 September. Small
    amounts of ash and lapilli were deposited NE of Asama.

    Many (not all) parts of the world now have Volcanic Ash Advisory Centers
    (VAACs) devoted to helping aviators avoid volcanic ash. They operate
    through agencies closely associated with aviation meteorology. The Tokyo
    VAAC website presents a diagram showing some fundamental linkages in its
    information management networks (figure 5). The diagram is only intended to
    provide an introductory overview (e.g., it is not comprehensive, and it may
    be outdated); however, it should make the role of the Tokyo VAAC in the
    Asama eruption more tangible to many in the volcano-monitoring community.

    Figure 5. A schematic showing some paths of information flow into and out
    of the Tokyo VAAC. The real communication patterns are considerably more
    complex and involve other communication links, such as those of the air
    carrier, between its aircraft to its own offices, and those directly
    between local observatories and meteorological offices. Inputs from people
    monitoring a volcano pass through a system with different conventions and
    procedures. Modified from a diagram on the Tokyo VAAC website.

    Volcano-monitoring input can pass to the VAAC via the paths labeled
    Domestic (in this case, Japan) and International (including the Kamchatkhan
    Volcanic Eruptions Response Team, the Philippine Institute of Volcanology
    and Seismology, the Alaska Volcano Observatory, and adjacent VAACs of
    Washington, Anchorage, and Darwin). In some examples of the latter
    communications, one VAAC may alert others that an ash plume may soon extend
    beyond the boundary of VAAC's area of responsibility. Sources of incoming
    data include that from satellites and from aircraft. The latter includes
    both PIREPS, pilot reports, and AIREPs, air reports routed via airlines.
    The VAAC prepares output to aviators that includes both Volcanic Ash
    Advisories and SIGMETS. The latter, SIGnificant METeorological messages
    contain information about hazardous phenomena, including weather, severe
    icing, turbulence, or volcanic ash that, in the judgment of the forecaster,
    are hazardous to aviation). The system continues to undergo refinement and
    exists under the auspices of the International Civil Aviation Organization
    (ICAO).

    Tokyo VAAC reported that eruptions during 23-25 September produced plumes,
    in some cases to unknown heights; and in one case to "FL 170" (aviation
    shorthand for 17,000 feet; ~5 km altitude; figure 6). In addition, minor
    ash eruptions occurred twice on 1 October. Afterwards a helicopter flight
    provided by the Nagano police (Shinshu) was carried out under conditions of
    clear sky with southerly winds, enabling observers to watch Asama's summit
    area during the hours of 0930-1100. They saw relatively weak emissions
    drifting N. A new vent, ~70 m in diameter and ~40 m in depth lay within the
    summit (Kamayama) crater. This was in accord with what had been observed on
    16 and 17 September by radar (SAR image of GSI) and also photographed by
    the press (Eg., Yomiuri Shimbun). From the eastern rim of the vent a crack
    of incandescence was observed, from which a jet of volcanic gas issued
    intermittently. Using an infrared camera, the highest temperature JMA
    measured was 517°C.

    Figure 6. A Volcanic Ash Advisory issued by Tokyo VAAC describing a 25
    September 2004 eruption at Asama that sent ash to ~ 5 km altitude (FL 170).
    Advisories such as this are the messages received on the flight deck of
    potentially affected aircraft and by the air carriers' dispatchers.
    Courtesy of the Tokyo VAAC.
    A minor explosive eruption occurred at 2310 on 10 October. Small amounts of
    ash and lapilli were deposited NNE of the volcano. The Tokyo VAAC reported
    this eruption produced a plume to an unknown height.

    The Tokyo VAAC reported an eruption on 16 October at 1206; it discharged a
    SE-drifting ash cloud higher than 3.4 km altitude. On 18 October at 1017, a
    N-drifting plume rose to ~3.4 km altitude.

    Asama erupted with a loud explosion on 14 November at 2059. JMA rated the
    eruption as mid-sized, 3 on a scale of 5, in terms of power of the
    explosion. The agency issued a warning of falling ash downwind of the
    volcano, although no ash plume was observed due to cloudy weather
    conditions. Following the explosion observers did see falling rocks over a
    large area on the volcano's slopes. There were no immediate reports of
    injuries or damage. Ash and lapilli were deposited E of Asama and ash-fall
    covered the N part of the Kanto area, reaching more than 100 km.

    Other tilt, GPS, seismic, and gravity data. A tilt anomaly was observed and
    announced by JMA on 22 February, but no eruption occurred. That inflation
    took place over about 3 months, beginning 14 November 2004. The series of
    eruptions in September 2004 was preceded by earthquake swarms and
    shorter-term tilt changes. The respective anomalies became significant a
    few days to half a day before the explosive events. Tiltmeters of JMA and
    ERI are located ~3 km N and ~4 km E of the summit crater. The former are
    more sensitive than the latter, probably due to Asama's inferred E- to
    W-trending (dike-shaped) magma body. The inflationary tilt measured 3 km N
    of the summit crater was as small as 10^-6 radians. The smaller tilt
    episodes remained below the detection threshold for the GPS network
    surrounding the volcano.

    Preceding the Vulcanian explosions on 1, 23, and 29 September, observers
    noticed frequent B-type earthquakes. They also documented small inflations
    of the summit area. These inflations occurred about half day to one day
    before the explosions. On the other hand, the explosive events during 16-17
    September followed deflation in the wake of a three-day inflation (10-13
    September).

    S. Okubo conducted continuous gravity measurements at the Asama Volcano
    Observatory (AVO) of ERI. Various explosive events of September reportedly
    occurred a few days after gravity shifted from an increase to a decrease.
    AVO's gravity station sits at 1,400 m elevation about 4 km E of the summit.
    Okubo proposed that the gravity changes reflected movement of magma within
    the conduit. Gravity decreased when the magma head rose above the
    observation level.

    Background. Asama, Honshu's most active volcano, overlooks the resort town
    of Karuizawa, 140 km NW of Tokyo. The volcano is located at the junction of
    the Izu-Marianas and NE Japan volcanic arcs. The modern cone of
    Maekake-yama forms the summit of the volcano and is situated E of the
    horseshoe-shaped remnant of an older andesitic volcano, Kurofu-yama, which
    was destroyed by a late-Pleistocene landslide about 20,000 years before
    present (BP). Growth of a dacitic shield volcano was accompanied by
    pumiceous pyroclastic flows, the largest of which occurred about
    14,000-11,000 years BP, and by growth of the Ko-Asama-yama lava dome on the
    E flank. Maekake-yama, capped by the Kama-yama pyroclastic cone that forms
    the present summit of the volcano, is probably only a few thousand years
    old and has an historical record dating back at least to the 11th century
    AD. Maekake-yama has had several major plinian eruptions, the last two of
    which occurred in 1108 and 1783 AD.

    Information Contacts: Yukio Hayakawa, Faculty of Education, Gunma
    University, Aramaki 4-2, Maebashi Gunma 371-8510, Japan (Email:
    hayakawa@edu.gunma-u.ac.jp, URL: maechan.net/hayakawa/asama/
    gankoran/, www.edu.gunma-u.ac.jp/~hayaka...h.html); Setsuya
    Nakada, Volcano Research Center, Earthquake Research Institute (ERI),
    University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113, Japan (Email:
    nakada@eri.u-tokyo.ac.jp; URL:
    www.eri.u-tokyo.ac.jp/topics/...e.html); Geological
    Survey of Japan (GSJ), National Institute of Advanced Industrial Science
    and Technology (GSJ AIST) (URL: www.gsj.jp/kazan/kazan-bukai/
    yochiren/asama040909/ material.html); Asia Air Survey Co., Ltd. (Email:
    info@ajiko.co.jp,ta.chiba@ajiko.co.jp,at.amano@ajiko.co.jp; URL:
    www.ajiko.co.jp/ topics/ct/ asama/); Geographical Survey Institute
    (radar and other methods), Ministry of Land,Infrastructure and Transport,
    Japan (URL: www.gsi.go.jp/BOUSAI/ASAM...dexsar.htm); Japan
    Meteorological Agency (JMA), Volcanological Division, Seismological and
    Volcanological Department, 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100-8122;
    Tokyo Volcanic Ash Advisory Center, Tokyo Aviation Weather Service Center,
    Haneda Airport 3-3-1, Ota-ku, Tokyo 144-0041, Japan
    (www.jma.go.jp/JMA_HP/jma/...index.html);
    International Civil Aviation Organization (ICAO), 999 University Street,
    Montreal, Quebec H3C 5H7, Canada (URL: www.icao.int/); Reuters.


    Raung
    eastern Java, Indonesia
    8.125°S; 114.042°E; summit elev. 3,332 m
    All times are local (= UTC + 8 hours)

    Though frequently active, Raung is seldom the subject of reports from
    either the news media or the Directorate of Volcanology and Geological
    Hazard Mitigation (DVGHM). The most recent Darwin VAAC report was issued
    late on 26 August 2002 (UTC). It noted that aviators had estimated an ash
    plume at ~10 km altitude drifting W (reported 25 August in an AIREP). Ash
    clouds were not visible on NOAA/GMS satellite imagery. A summary of Darwin
    VAAC reports of Raung for the period July 1999-August 2002 was given in
    Bulletin v. 29, no. 1.

    There were nine anomalous Moderate Resolution Imaging Spectroradiometer
    (MODIS) observations of volcanic hot spots at Raung during 3 June-8 October
    2004 (table 1). The 2004 alerts were the first detected by MODIS at Raung.
    Minor explosive activity documented intermittently during 1999 to 2002
    (Bulletin v. 29, no. 1) did not have a thermal component sufficient to
    trigger alerts.

    Table 1. Thermal anomalies at Raung observed with MODIS during 2004. Some
    of the UTC times were for the previous date. Spectral radiance for the hot
    pixels in band 21 (central wavelength of 3.959 um) are in units of watts
    per square meter per steradian per micron (W-2 sr-1 um-1). Courtesy of the
    Hawaiian Institute of Geophysics and Planetology.

    Date (2004) Time (local / UTC) Spectral radiance

    15 Apr 2300 / 1500 0.852
    16 Apr 0200 / 1800 (15 Apr) 0.847
    22 Apr 2310 / 1510 0.814
    02 May 0200 / 1800 (01 May) 0.813
    03 Jun 0200 / 1800 (02 Jun) 0.677
    18 Jun 2300 / 1500 0.729
    04 Jul 2300 / 1500 0.795
    11 Jul 2310 / 1510 0.814
    14 Jul 0155 / 1755 (13 Jul) 0.778
    22 Sep 2300 / 1500 0.849
    23 Sep 0200 / 1800 (22 Sep) 0.740
    29 Sep 2305 / 1505 0.893
    08 Oct 2300 / 1500 0.776

    No ground observations have been reported during 2004, but in a message
    from Dali Ahmad (DVGHM), he noted the absence of observed emissions during
    2004. With respect to the thermal alerts, he speculated that they could
    conceivably have originated from brush fires. Rob Wright commented that the
    levels of radiance in the 2004 alerts were both "too weak and too
    intermittent to be lava flows" and stood near the system's lower threshold.
    Similar weak anomalies occur at volcanoes such as Villarrica and during
    intervals at Anatahan, but the source of the alerts at Raung remains uncertain.

    Clear aerial photographs of Raung were taken on 26 and 30 July 2001 (figure
    7) by Franz Jeker of Singapore Airlines as he flew past in descent towards,
    or ascent from, the Bali airport. Jeker also included a detailed map of the
    Raung area (figure 8).

    Figure 7. A photograph taken on 26 July 2001 of a small fumarolic plume
    from the central crater of Raung looking SW during a fly-by of a commercial
    airplane across the NNE flank. Courtesy of F. Jeker.

    Figure 8. Map showing relative locations of Raung volcano at the SW end of
    Java, and adjacent Bali. Courtesy of F. Jeker.

    Background. Raung, one of Java's most active volcanoes, is a massive
    stratovolcano in easternmost Java that was constructed SW of the rim of
    Ijen caldera. The 3,332-m-high, unvegetated summit of Gunung Raung is
    truncated by a dramatic steep-walled, 2-km-wide caldera that has been the
    site of frequent historical eruptions. A prehistoric collapse of Gunung
    Gadung on the W flank produced a large debris avalanche that traveled 79 km
    from the volcano, reaching nearly to the Indian Ocean. Raung contains
    several centers constructed along a NE-SW line, with Gunung Suket and
    Gunung Gadung stratovolcanoes being located to the NE and W, respectively.

    Information Contacts: Directorate of Volcanology and Geological Hazard
    Mitigation (DVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (Email:
    dali@vsi.dpe.go.id; URL: www.vsi.esdm.go.id/); Darwin Volcanic Ash
    Advisory Center (VAAC), Bureau of Meteorology, Northern Territory Regional
    Office, PO Box 40050, Casuarina, NT 0811, Australia (URL:
    www.bom.gov.au/info/vaac/...ries.shtml; Email:
    Darwin.vaac@bom.gov.au); Hawai'i Institute of Geophysics and Planetology
    (URL: modis.higp.hawaii.edu); Franz Jeker, Rigistrasse 10, 8173
    Neerach, Switzerland (Email: franz.jeker@swissonline.ch).


    Kerinci
    Sumatra, Indonesia
    1.814°S, 101.264°E; summit elev. 3,800 m
    All times are local (= UTC + 7 hours)

    Events at Kerinci were previously discussed through 29 August 2004
    (Bulletin v. 29, no. 8). The following report overlaps slightly, covering
    17 July through 24 October 2004. As already reported, on 24 July 2004 a
    thick plume rose to 100-600 m above the crater rim, ash fell ~3 km from the
    crater forming deposits as thick as 1 cm. Seismicity is summarized in table 2.

    Table 2. Volcanic seismicity registered at Kerinci during 17 July to 24
    October 2004. Courtesy of DVGHM.

    Date (2004) Volcanic A Volcanic B Emission

    17 Jul-24 Jul 2 1 0.5-3
    24 Jul-31 Jul 5-6 3 0.5-5
    02 Aug-08 Aug 5 2 continue
    09 Aug-15 Aug 1 1 continue
    16 Aug-22 Aug 2 2 continue
    23 Aug-29 Aug -- 1 continue

    27 Sep-03 Oct 5 1 continue
    04 Oct-10 Oct -- 1 continue
    11 Oct-17 Oct -- 2 continue
    18 Oct-24 Oct 3 2 continue

    There were six Darwin VAAC reports on Kerinci in 2004, two on 21 June and
    four on 27 September. (Prior to that the VAAC reports were clustered in
    mid- to late-August 2002.) The 21 June cases discussed a continuous
    emission with ash to ~4 km drifting W. The 27 September cases began with
    and then repeated an aviator's statement (an AIREP at 0136 UTC 27
    September), noting that ash was observed to ~6 km, drifting W. For all six
    cases (June and September), the VAAC staff noted that due to cloud cover,
    ash was not visible in satellite data.

    Kerinci erupted on 6 August 2004 at 0835 hours. Gray ash rose to 50-600 m
    above the summit. The hazard status was raised to Alert Level II (yellow)
    at 1030, where it stayed for the remainder of this report period.

    During 9-15 August 2004 the number of earthquakes decreased. A white thin
    plume again rose to 50-300 m above the summit. Volcanic activity remained
    relatively stable from 15 August through 24 October 2004, with thick gray
    plumes rising 50-300 m above the summit.

    Background. The 3,800-m-high Gunung Kerinci in central Sumatra forms
    Indonesia's highest volcano and is one of the most active in Sumatra.
    Kerinci is capped by an unvegetated young summit cone that was constructed
    NE of an older crater remnant. The volcano contains a deep 600-m-wide
    summit crater often partially filled by a small crater lake that lies on
    the NE crater floor, opposite the SW-rim summit of Kerinci. The massive 13
    x 25 km wide volcano towers 2400-3300 m above surrounding plains and is
    elongated in a N-S direction. The frequently active Gunung Kerinci has been
    the source of numerous moderate explosive eruptions since its first
    recorded eruption in 1838.

    Information Contacts: DVGHM (see Raung).


    Marapi
    Sumatra, Indonesia
    0.38°S, 100.47°E; summit elev. 2,891 m

    The most recent previous explosive activity at Marapi peaked during 13-18
    April 2001, when a total of 150 explosions occurred that sent ash plumes to
    2 km above the summit (Bulletin v. 27, no. 1). This report covers the
    interval 5 August to 10 October 2004.

    On 5 August 2004 Marapi generated a small eruption with a gray to black ash
    cloud that rose to 500-1,000 m above the summit. Its hazard status was
    raised to Alert Level II (yellow), where it remained throughout this period.

    Total numbers of seismic events from 2 August through 10 October 2004 are
    listed in table 3. During some weeks in August the number of earthquakes
    increased markedly. A thin white plume rose to 50 m above the summit on 10
    August. During 16-29 August a thin white-gray plume rose to ~75-100 m.
    Similar plumes rose to ~50 m during 27 September-3 October and to ~300 m
    during 4-10 October. Seismic signals inferred to be related to emissions
    were elevated during several weeks of the reporting interval, particularly
    in August (table 3).

    Table 3. A summary of volcanic seismicity at Marapi during 2 August to 10
    October 2004. Courtesy of DVGHM.

    Date Volc A Volc B Tremor Emission

    02 Aug-08 Aug 1 11 -- --
    09 Aug-15 Aug 2 6 -- 20
    16 Aug-22 Aug -- 3 -- 21
    23 Aug-29 Aug -- 3 2 14

    20 Sep-26 Sep -- -- -- --
    27 Sep-03 Oct 1 -- -- --
    04 Oct-10 Oct 3 -- -- 8

    There were no MODIS-MODVOLC alerts at Marapi during 2004.

    Background. Gunung Marapi, not to be confused with the better-known Merapi
    volcano on Java, is Sumatra's most active volcano. Marapi is a massive
    complex stratovolcano that rises 2,000 m above the Bukittinggi plain in
    Sumatra's Padang Highlands. A broad summit contains multiple partially
    overlapping summit craters constructed within the small 1.4-km-wide Bancah
    caldera. The summit craters are located along an ENE-WSW line, with
    volcanism migrating to the W. More than 50 eruptions, typically consisting
    of small-to-moderate explosive activity, have been recorded since the end
    of the 18th century; no lava flows outside the summit craters have been
    reported in historical time.

    Information Contacts: DVGHM (see Raung); Darwin Volcanic Ash Advisory
    Center (VAAC) (see Raung).


    Etna
    Italy
    37.734°N, 15.004°E; summit elev. 3,350 m

    The effusive eruption that started on 7 September 2004 on the W wall of the
    Valle del Bove continued. Lava escaped at a very low effusion rate from two
    main vents at 2,620 and 2,320 m elevation. Lava tubes developed downslope
    of these vents, forming a complex lava-flow field with ephemeral vents at
    the base of the W wall of the Valle del Bove. After December 2004, effusive
    vents were mainly located at the lower end of the tube network below 2,000
    m elevation. Lava flows were up to 2.5 km long, and the lava-flow field did
    not change significantly since the end of October 2004 (figure 9).

    Figure 9. A map of Etna emphasizing features associated with the lava flow
    field as they appeared 4 October 2004. Courtesy of INGV.

    On 8 January 2005 an ash plume formed above the summit of SE crater and
    lasted a few hours. Analysis of the ash components revealed that it
    consisted of lithic material. This episodic ash emission was probably
    caused by collapse within the crater into the void left after three months
    of lava output.

    On 18 January the INGV-CT web camera located 27 km S of the summit craters
    revealed a dense, pulsating gas plume rising above the summit of NE crater
    and lasting a few minutes. This was probably caused by snow vaporization
    due to hot gas emission from the main crater vent.

    During the afternoon of 18 January a new lava flow formed upslope along the
    2,620-m-long eruptive fissure, at ~2,450 m elevation. The lava flow spread
    for about 200 m SE on the snow and along the middle wall of the western
    Valle del Bove. This flow front moved slowly and completely stopped after
    about 24 hours. The emission of lava from the ephemeral vents below 2,000 m
    stopped during the effusion from the 2,450-m vent. The lower ephemeral
    vents again started to emit lava on 19 January. During the afternoon of 22
    January two new lava flows erupted from vents at 2,400 m elevation, along
    the same tube system fed by the 2,620-m-elevation vent. Two parallel,
    fast-moving flows spread E. They were still evident on 27 January from the
    images recorded by the INGV-CT webcam at Milo, together with a number of
    ephemeral vents and small lava flows at the lower end of the lava tube.

    The opening of effusive vents upslope along the tube system of a complex
    lava-flow field has usually indicated the final stages of expansion, an
    effect observed several times at lava-flow fields on Etna and Stromboli.
    Decreased effusion from the main vent causes the tube system to drain, so
    the lava tube walls collapse. Obstruction at the lower end of the tube then
    causes accumulation of lava farther upslope and the opening of new vents at
    higher elevations.

    Since the start of the eruption on 7 September 2004 (Bulletin v. 29, no.9),
    there has been no significant explosive activity at the summit craters or
    the eruptive fissures.

    Background. Mount Etna, towering above Catania, Sicily's second largest
    city, has one of the world's longest documented records of historical
    volcanism, dating back to 1500 BC. Historical lava flows of basaltic
    composition cover much of the surface of this massive volcano, whose
    edifice is the highest and most voluminous in Italy. The most prominent
    morphological feature of Etna is the Valle del Bove, a 5 x 10 km
    horseshoe-shaped caldera open to the E. Two styles of eruptive activity
    typically occur at Etna. Persistent explosive eruptions, sometimes with
    minor lava emissions, take place from one or more of the three prominent
    summit craters, the Central Crater, NE Crater, and SE Crater (the latter
    formed in 1978). Flank vents, typically with higher effusion rates, are
    less frequently active and originate from fissures that open progressively
    downward from near the summit (usually accompanied by Strombolian eruptions
    at the upper end). Cinder cones are commonly constructed over the vents of
    lower-flank lava flows. Lava flows extend to the foot of the volcano on all
    sides and have reached the sea over a broad area on the SE flank.

    Information Contacts: Sonia Calvari, Istituto Nazionale di Geofisica e
    Vulcanologia, Piazza Roma 2, 95123 Catania, Italy (URL:
    www.ct.ingv.it/, Email: calvari@ct.ingv.it).


    Erta Ale
    Ethiopia
    13.60°N, 40.67°E; summit elev. 613 m

    An expedition led by the volcanology travel group SVE-SVG visited Erta Ale
    during 22-23 January 2005. The observed eruptive activity was generally
    unchanged since November 2004 (Bulletin v. 29, no. 11). Degassing was still
    occurring from three of the four hornitos in the SW part of the South
    crater, but had decreased slightly in comparison with their December 2004
    observations. The hornitos stood ~10 m high and represented the only
    portion of the lava crust covering the crater floor where gas emissions
    were seen. A window in the upper part of one of the hornitos permitted
    observation of glowing molten lava.

    On 23 January 2005 members of the group descended into the crater and
    collected recent lava that had poured out from the hornitos during partial
    collapse. Degassing activity (mainly SO2) from the North crater had also
    slightly decreased in comparison with early December 2004 observations.

    From a small terrace in the NW part of the crater it was possible to
    observe degassing from several hornitos (some several meters high in the
    central part of the 'lava bulge'). Near the NW wall of the crater two
    small, red glowing areas were visible at the summit of two other hornitos.

    Chemical analyses. The following complements a previous Erta Ale report by
    Jacques-Marie Bardintzeff from November-December 2004 (Bulletin v. 29,
    no.11). He sampled molten lava at 12 m depth in one of the hornitos of the
    crater on 5 December 2004 using a cable and an iron mass, and subsequently
    analyzed the chilled glass sample using an electron microprobe (table 4).

    Table 4. Major-element chemistry of Erta Ale lava resulting from 18
    representative glass analyses. Courtesy of Jacques-Marie Bardintzeff.

    Oxide Weight percent

    SiO2 48.61-49.64
    Al2O3 12.99-13.60
    TiO2 2.37- 2.66
    MgO 6.13- 6.39
    FeO 11.25-12.20
    Cr2O 0- 0.11
    MnO 0.03- 0.34
    CaO 10.63-11.41
    Na2O 2.81- 3.08
    K2O 0.54- 0.69
    Total 97.44-98.71

    Analysis also revealed some plagioclase phenocrysts (An = 80.9-70.4) as
    well as scarce clinopyroxene microcrysts (Wo = 43.5-44.0, En = 45.8-45.9,
    Fs = 10.2-10.6). Compared to the matrix glasses shown in table 4, glass
    inclusions trapped in plagioclase were richer in SiO2 (50.07-50.41 wt%) and
    poorer in TiO2 (1.84-1.95 wt %).

    Correction. French scientists led by Jacques-Marie Bardintzeff and Franck
    Pothe visited the summit of Erta Ale on 13-14 January 2003 (Bulletin v. 28,
    no.4). At that time the lava lake in the S pit crater was 180 m long, not
    120 m as previously reported.

    Background. Erta Ale is an isolated basaltic shield volcano that is the
    most active volcano in Ethiopia. The broad, 50-km-wide volcano rises more
    than 600 m from below sea level in the barren Danakil depression. Erta Ale
    is the most prominent feature of the Erta Ale Range. The volcano contains a
    0.7 x 1.6 km, elliptical summit crater housing steep-sided pit craters.
    Another larger 1.8 x 3.1 km wide depression elongated parallel to the trend
    of the Erta Ale range is located to the SE of the summit and is bounded by
    curvilinear fault scarps on the SE side. Fresh-looking basaltic lava flows
    from these fissures have poured into the caldera and locally overflowed its
    rim. The summit caldera is renowned for long-term lava lakes that have been
    active since at least 1967, or possibly since 1906. Recent fissure
    eruptions have occurred on the northern flank.

    Information Contacts: Jacques-Marie Bardintzeff, Laboratoire de
    Petrographie-Volcanologie, Bât. 504, Universite Paris-Sud, F-91405, Orsay,
    France (Email: bardizef@geol.u-psud.fr, URL:
    www.lave-volcans.com/bardintzeff.html); Franck Pothe, Terra
    Incognita, CP 701, 36 quai Arloing 69256 Lyon Cedex, France (Email:
    ti@terra-incognita.fr); Henry Gaudru, Georges Kourounis, Derek Tessier,
    Brian Fletcher, Alexander Gerst, and Motomaro Shirao, Societe
    Volcanologique Europeenne (SVE)-Societe Volcanologique (SVG), Geneva,
    C.P.1, 1211 Geneva 17, Switzerland (URL: www.sveurop.org/, Email:
    HgaudruSVE@compuserve.com).


    Popocatepetl
    central Mexico
    19.023°N, 98.622°W; summit elev. 5,426 m
    All times are local (= UTC 6 hours)

    During 2004, Popocatepetl showed an overall low level of activity. Apart
    from a few low-intensity exhalations, no significant seismicity,
    deformation, or geochemical changes in spring waters were detected. The
    crater (figure 10) did not show significant morphological changes other
    than hydrologic effects, and no evidence of lava dome emplacements were
    observed. During December, relatively low-level volcanism prevailed,
    including low-intensity steam-and-gas emissions (table 5). An aerial
    photograph taken on 10 December showed subsidence in the inner crater and
    no external lava dome at the bottom of the crater. The Alert Level remained
    at Yellow Phase II.

    Figure 10. Annotated aerial photograph of Popocatepetl's summit area taken
    12 November 2004. Courtesy of CENAPRED; the Mexican Secretary of
    Communications and Transportation; and Servando De la Cruz, UNAM.

    Table 5. Summary of various observations at Popocatepetl during December
    2004 (chiefly visual confirmations of ongoing emission). Courtesy of CENAPRED.

    Date (2004) Exhalations Other Observations

    01 Dec-04 Dec Low-intensity (9-13 per day) Light steam-and-gas emissions
    05 Dec-07 Dec Low-intensity (16-19 per day) Light steam-and-gas emissions
    08 Dec-09 Dec Low-intensity (7-10 per day) Light steam-and-gas emissions
    10 Dec Low-intensity (11) Aerial photograph showed
    subsidence in the inner
    crater; no external lava
    dome at the bottom of the
    crater can be distinguished
    11 Dec-16 Dec Low-intensity (3-10 per day) Light steam-and-gas emissions
    17 Dec-21 Dec Low-intensity (2-5 per day) Light steam-and-gas emissions
    22 Dec-27 Dec Low intensity (6-10 per day) Light steam-and-gas emissions
    28 Dec Low-intensity (19) Light steam-and-gas emissions
    29 Dec-31 Dec Low-intensity (9-11 per day) Light steam-and-gas emissions

    At the end of December 2004, however, a slight increase in seismic activity
    was detected (table 5). On 20 and 29 December 2004 two exhalations, small
    yet exceeding the average for the year, were followed in early January 2005
    by a series of phreatic explosions. The major events were detected on 9
    January at 2245 and on 22 January at 2358. These were the largest events
    detected in the past 15 months. In both cases, light ashfall was reported
    on the towns of Cuautla (<40 km SSW of the volcano), and San Martin
    Texmelucan (37 km NE of the crater). In an aerial photograph taken on 14
    January 2005 the inner crater appears deeper than previously shown, with no
    evidence of magmatic activity (figure 11).

    Figure 11. Annotated photograph of Popocatepetl's summit area taken 14
    January 2005. A label identifies a small craterlet on the southern inner
    wall of the inner crater. These type of craterlets have been repeatedly
    formed by moderate explosions or exhalations. They have tended to be
    ephemeral, lasting only until the next event. Courtesy of CENAPRED; the
    Mexican Secretary of Communications and Transportation; and Servando De la
    Cruz, UNAM.
    Background. Volcan Popocatepetl, whose name is the Aztec word for smoking
    mountain, towers to 5,426 m 70 km SE of Mexico City to form North America's
    2nd-highest volcano. The glacier-clad stratovolcano contains a
    steep-walled, 250-450 m deep crater. The generally symmetrical volcano is
    modified by the sharp-peaked Ventorrillo on the NW, a remnant of an earlier
    volcano. At least three previous major cones were destroyed by
    gravitational failure during the Pleistocene, producing massive
    debris-avalanche deposits covering broad areas south of the volcano. The
    modern volcano was constructed to the south of the late-Pleistocene to
    Holocene El Fraile cone. Three major plinian eruptions, the most recent of
    which took place about 800 AD, have occurred from Popocatepetl since the
    mid Holocene, accompanied by pyroclastic flows and voluminous lahars that
    swept basins below the volcano. Frequent historical eruptions have occurred
    since precolumbian time.

    Information Contacts: Alicia Martinez Bringas, Angel Gomez Vazquez, Roberto
    Quass Weppen, Enrique Guevara Ortiz, Gilberto Castelan Pescina, and Cesar
    Morquecho Zamarripa, Centro Nacional de Prevencion de Desastres (CENAPRED),
    Av. Delfin Madrigal No.665. Coyoacan, Mexico D.F. 04360. Email:
    amb@cenapred.unam.mx gvazquez@cenapred.unam.mx; URL:
    www.cenapred.unam.mx/); Servando De la Cruz-Reyna, Instituto de
    Geofisica, UNAM Cd. Universitaria. Circuito Institutos, Coyoacan, D.F.
    04510, Mexico (Email: sdelacrr@tonatiuh.igeofcu.unam.mx, URL:
    www.geofisica.unam.mx).


    Colima
    western Mexico
    19.514°N,103.62°W; summit elev. 3,850 m

    New emissions of block-lava flows began on 30 September 2004 after 19
    months of intermittent explosive activity. During February 2002-February
    2003 the lava dome extruded effusively, but it was destroyed by the
    July-August 2003 explosions (Bulletin v. 28, no. 6; and v. 29, no. 5).
    Thus, beginning in September 2003 the upper crater lacked a visible dome.

    The new lava effusions that began on 30 September took place without either
    premonitory swarms of volcano-tectonic earthquakes or significant
    deformation of the volcanic edifice. A 6-hour episode of volcanic tremors
    was observed on 20 September (figures 12 and 13).

    Figure 12. Plots of Colima activity during September-November 2004: (A)
    Lava emission rate; and (B) Number of earthquakes produced by rockfalls and
    pyroclastic flows (PF) (heavy line) and by explosions and exhalations
    (dashed line). Arrows show the tremor episode and the start of the
    eruption. Courtesy of Colima Volcano Observatory.

    Figure 13. Seismic record showing the start of the tremor episode (towards
    the bottom) as registered at station EZV4 situated at a distance of 1.4 km
    from the crater. Courtesy of Colima Volcano Observatory.

    On 28 September, intensive fumarolic activity began in the crater, forming
    a 500-m-high column of white gas. An overflight that day permitted
    observation of a new lava extrusion that practically filled the crater. An
    intensive swarm of seismic events produced by rockfalls and pyroclastic
    flows began at about 0600 on 30 September. The seismic events indicated the
    overflow of lava from the crater and heralded the formation of two
    andesitic block-lava flows. These flows began to develop along Colima's N
    and WNW slopes.

    During October and November, lava emission continued at a decreasing rate
    (figure 12). The lava emissions were effusive and accompanied by frequent
    small explosions and exhalations. Numerous block-and-ash flows extended
    ~4.5 km from the summit (figure 14). Seismic intensity closely tracked with
    variations in the lava emission rate.

    Figure 14. An oblique aerial photo showing a new lobe of blocky lava
    emplaced on Colima's N flank. Photo was taken on 27 October 2004. Courtesy
    of Colima Volcano Observatory.

    By 1 December, the two lava flows stretched ~2,400 m long and ~300 m wide
    on the N flanks, and ~600 m long and 200 m wide on the WNW flanks (figure
    14). The total volume of erupted material including lava and
    pyroclastic-flow deposits was ~8.3 x 10^6 m^3.

    Background. The Colima volcanic complex is the most prominent volcanic
    center of the western Mexican Volcanic Belt. It consists of two
    southward-younging volcanoes, Nevado de Colima (the 4,320-m-high point of
    the complex) on the N and the 3,850-m-high historically active Volcan de
    Colima at the south. A group of cinder cones of probable late-Pleistocene
    age is located on the floor of the Colima graben west and east of the
    Colima complex. Volcan de Colima (also known as Volcan Fuego) is a youthful
    stratovolcano constructed within a 5-km-wide caldera, breached to the
    south, that has been the source of large debris avalanches. Major slope
    failures have occurred repeatedly from both the Nevado and Colima cones,
    and have produced a thick apron of debris-avalanche deposits on three sides
    of the complex. Frequent historical eruptions date back to the 16th
    century. Occasional major explosive eruptions (most recently in 1913) have
    destroyed the summit and left a deep, steep-sided crater that was slowly
    refilled and then overtopped by lava dome growth.

    Information Contact: Observatorio Vulcanologico de la Universidad de
    Colima, Colima, Col., 28045, Mexico (Email: ovc@cgic.ucol.mx).
    __________________________________________________________
    Global Volcanism Program, NHB E-421 Tel: (202) 633-1800
    Smithsonian Institution Fax: (202) 357-2476
    Washington, DC 20560-0119 Email: gvp@si.edu

    Internet: www.volcano.si.edu/
  • Re: GVN Bulletin

    Mon, April 11, 2005 - 10:37 AM
    ********************************************************
    Bulletin of the Global Volcanism Network, February 2005
    ********************************************************
    From: Ed Venzke <venzke@volcano.si.edu>


    Bulletin of the Global Volcanism Network
    Volume 30, Number 2, February 2005

    Manam (Papua New Guinea) One death, 14 injuries due to 27 January eruption;
    stratospheric injection
    Rinjani (Indonesia) Witnessed eruptions in October 2004 with material
    escaping from two vents
    Anatahan (Mariana Islands) Remotely sensed ash plumes in February; Guam
    air-quality problems
    Asama (Japan) Maps of 2004 tephra deposits; radar images of the crater's
    interior and a dome
    Shiveluch (Kamchatka) 27 February eruption left deposits covering 24,800
    km2 to W of volcano
    Veniaminof (Alaska) Ash emissions in January and Strombolian eruptions in
    February
    St. Helens (USA) On 21 February the still-growing dome stood 160 m higher
    than the 1980's dome
    Kick 'em Jenny (W Indies) Monitored and quiet; multi-beam finds craters and
    domes
    Marion Island (South Africa) Small eruption seen 24 June 2004 on S side of
    this Antarctic island

    Editors: Rick Wunderman, Edward Venzke, and Gari Mayberry
    Volunteer Staff: Robert Andrews, Jacquelyn Gluck, William Henoch, and
    Catherine Galley


    Manam
    Papua New Guinea
    4.10°S, 145.061°E; summit elev. 1,807 m
    All times are local (= UTC + 10 hours)

    On 24 October 2004 a strong eruption occurred at Manam (Bulletin v. 29, no.
    10). Several more significant eruptions followed in late 2004 (Bulletin v.
    29, no. 11), leading to the most severe and damaging one, which took place
    on 27 January 2005. That event occurred in conditions favorable to
    satellite imagery, enabling Andrew Tupper of the Darwin Volcanic Ash
    Advisory Centre (VAAC), and colleagues, to confirm that the associated ash
    cloud reached to over 20 km altitude, well into the stratosphere.

    Satellite remote sensing documented 5 eruption plumes ascending to over 15
    km during this issue's reporting interval, 23 October 2004-28 January 2005.
    One additional plume may have been missed by remote sensing in adverse
    weather conditions. Various images from the 2004 and 2005 eruptions are on
    the Darwin VAAC website (see Information Contacts, below). Sulfur dioxide
    is discussed there as well as on websites of the OMI-TOMS Volcanic
    Emissions Group and related sites.

    The Bulletin has benefitted from reports by the Rabaul Volcano Observatory
    (RVO), the media, and the Darwin VAAC. Although the 27 January eruption
    received comparatively little press coverage, it caused several injuries
    and one death. RVO staff working at Manam faced challenging, hazardous
    conditions. The island had been home to ~ 9,500 now-displaced residents.

    Summary of RVO observations. During the reporting interval both lava flows
    and pyroclastic flows reached the sea at various times (Bulletin v. 29,
    nos. 10 and 11). The main pathways were the NE and SE valleys (table 1,
    figures 1 and 2). Intervals of tremor were common.

    Table 1. A summary of RVO observations involving lava flows and pyroclastic
    flows associated with Manam's eruptions during 23 October 2004-28 January
    2005. Andrew Tupper (of the Darwin VAAC) compiled this list from available
    RVO reports and communications with RVO staff.

    Date Event at Manam

    24 Oct 2004 Pyroclastic flows reached the sea and lava flowed
    600 m down the SE valley.
    31 Oct 2004 Three lobed lava flow in NE valley, and possibly a
    small flow in the NW
    valley.
    11 Nov 2004 Lava in NE valley.
    23-24 Nov 2004 Lava in NE valley. "The flow that headed towards
    Bokure 1 terminated about
    100 m away from the main road . . . the Kolang
    lava flow had reached the
    sea" (reported by Warisi observer Herman Tibong).
    Ash on roofs caused a
    number of houses to collapse.
    19-20 Dec 2004 Lava and pyroclastic flows in SE valley. Pyroclastic
    flows stopped 200 m
    from the sea on the 19th (no report on what
    happened on the 20th).
    27-28 Jan 2005 14 injured and 1 dead at Warisi; debris voluminous
    and widespread on the
    island; ashfall reported ~230 km W of Manam.

    Figure 1. Map of Manam island made or updated circa 2002 (contour interval,
    200 m). A temporary observatory was at Warisi (triangle, 'current seismic
    station') on the island's E side, but the eruption on 27 January 2005
    destroyed it. Approximate trends of radial valleys were added by Bulletin
    editors. Courtesy of RVO.

    Figure 2. Annotated image of Manam indicating village and other place names
    on a false-color satellite photo (note the cloud cover; for scale, compare
    to previous figure). Source details are unknown. "Waris," is more commonly
    spelled "Warisi" in RVO reports. Courtesy of the PNG Mapserver website.

    Eruption on 27 January 2005. RVO reported that eruptive activity during the
    evening of 27 January was more severe than previous eruptions of the
    current eruptive period. As indicated on table 1, during 27-28 January
    there were 14 people injured and one person killed at Warisi village. RVO's
    monitoring base at Warisi was completely destroyed, taking out its HF
    radio, seismograph, and a satellite phone, thus preventing RVO from
    providing information on the current level of activity. The phone had been
    donated by an airline just a few weeks prior, provided as a means of aiding
    eruption-warning efforts. The station sat on the E flank at Warisi village
    (figures 1 and 2). RVO later recovered the station's seismograph and
    installed it on the island's NW side; they also restored radio communications.

    According to the Papua New Guinea (PNG) news source, The National, some
    people had returned on 27 January from the displacement camps on the
    mainland to gather food from their island gardens, only to have their boat
    destroyed by impacts from erupted rocks. The National also reported that
    many of the residents of the island who were originally evacuated in
    November 2004 had returned. There were reports of several houses that had
    burned down from hot emissions and others that collapsed under the weight
    of ash and pyroclastic material. It was reported that after the large
    eruption on 27 January, local authorities planned to evacuate about 2,000
    residents.

    Ash fell at ~230 km W of Manam (in Ambunti district, East Sepik province,
    PNG). Tupper recognized NW monsoon winds that took low-level ash SE. Thus,
    the ash that fell in Ambunti must have traveled at a higher altitude, which
    Tupper estimated to be above 6 km altitude.

    The October-January eruptive sequence. Figure 3 plots eruption heights
    versus time during 23 October 2004 to late January 2005. Three kinds of
    eruption-height estimates appear: those from pilot reports, RVO's estimates
    (ground-based observations), and Tupper's post-analysis studies of
    satellite data. In a descussion below, Tupper mentions the differences
    between the three height-estimate techniques. The line showing alert level
    corresponds to the right-hand scale. Six eruptive clouds are clear on the
    graph.

    Figure 3. A graph of Manam's cloud heights from 23 October 2004 to
    late-January 2005, as determined from various means (see key along top).
    The dashed line corresponds to the right-hand scale of the graph, which
    displays alert levels reported by RVO (0-4, with 4 as the highest).
    Courtesy of Andrew Tupper, Darwin VAAC.

    The 24 October eruption at Manam occurred just before the Terra and Aqua
    satellites passed over. The data from those satellites, and from AVHRR and
    GOES satellites, indicated a very ice-rich cloud. Associated with Manam's
    eruption on 24 October, the coldest temperature measured from the
    high-level cloud was about 204 K (a couple of hours after the eruption),
    which translated to an altitude of about 15-18 km (a height supported by
    the ash cloud's subsequent dispersion, including wind trajectories
    consistent with the ~18 km altitude plotted on figure 3). There was no
    evidence of significant stratospheric penetration. Pilot reports for the
    cloud's top were generally lower, as is usual for large eruptions (Tupper
    and Kinoshita, 2003).

    Figure 4 presents a photo of the 11 November eruption plume as seen by Air
    Niugini pilot David Innes. He estimated the visible portion of the plume
    height at "30,000 feet" (~9 km), but the cloud probably ascended at least a
    bit higher as it entered into masking cirrus clouds from a tropical
    disturbance to the N, so the pilot's estimate might be stated as 'above 9
    km.' RVO's ground observer estimated a plume at ~8 km slightly earlier in
    the eruption, on about 10 November. The satellite-based analysis was
    thwarted by the cirrus cloud cover during this eruption.
    Figure 4. A N-looking aerial photo showing Manam's plume at 0630 local time
    on 11 November 2004. The plume extends to ~9 km before disappearing into
    higher weather clouds. Photo by David Innes of Air Niugini; used here with
    his permission.

    From 20 December until just before the 27 January eruption, no plumes or
    hot spots were visible. Few plumes were reported by RVO, and none were seen
    by pilots (table 1). The 27 January eruption began about 1400 UTC; and an
    Aqua/MODIS image from 0507 UTC is shown as figure 5.

    Figure 5. An infrared Aqua/MODIS image of the umbrella cloud from the 27
    January 2005 Manam eruption (taken at 1535 UTC on the night of the 27th).
    The image is enhanced to show the 'warm spot' in the centre of the cloud
    (warm because of the stratospheric intrusion) and the gravity waves in the
    cloud. The lobate structure at the fringes of the cloud is similar to other
    observed umbrella clouds, such as the 1991 Pinatubo cloud. At this stage
    the cloud had a diameter of approximately 180 km. Courtesy of Andrew Tupper.

    The Darwin VAAC initially estimated the 27 January eruption cloud's maximum
    height as 21 km altitude, but later analysis found the range 21-24 km a
    better estimate. Infrared 11-um imagery from GOES-9 at 1440 UTC and
    Aqua/MODIS at 1539 UTC on 27 January showed 'warm' spots in the middle of
    the umbrella cloud of 215.4 K and 210.4 K, respectively, indicating a
    substantial overshoot of the cloud top into the warmer stratosphere
    (tropopause temperatures were around 187 K). The GOES-9 temperature may be
    less useful because of poorer satellite resolution and calibration, and
    because at that stage the cloud may not have come into equilibrium with its
    environment. Comparing these temperatures to a temperature sonde taken from
    nearby Manus Island at 0000 UTC on 28 January suggests a cloud altitude of
    21-24 km. Tupper plotted the more conservative (smaller) value on figure 3.

    The 27 January eruption cloud was extremely difficult to track, as it was
    ice-rich and mixed with monsoonal storms, but dispersion models and
    satellite analysis suggest that a mid-tropospheric portion spread quite
    quickly W over Irian Jaya, while higher cloud remained near the eruption
    site for some time. The best 'tracer' for the cloud in operations turned
    out to be the strong 'ice' signature in split-window imagery¾similar to the
    Hekla (Iceland) eruption in the year 2000.

    Another large eruption occurred around 2300 on 28 January. That plume's
    height plots at 18 km altitude (figure 3).

    Preliminary synopsis. Tupper wrote that he and his group were aware of five
    or six major events "during these [Manam] eruptions that have generated
    high (over 10 km altitude) eruption clouds--23-24 October 2004, 31 October
    2004, 10-11 November 2004, 23-24 November 2004, 19-20 December 2004, and
    27-28 January 2005 [figure 3]. On each of these occasions a high and
    sometimes persistent cloud has developed over a stronger phase of the
    eruption. The largest event by far has been the 27-28 January event, which
    was the only one to clearly penetrate into the stratosphere.

    "Attached is a graph [figure 3] showing the heights reported by ground
    observers, by local pilots, and derived from satellite analysis. Some major
    differences of perspective are evident. I believe that, in general, the
    ground observer heights are most accurate for the lower eruptions, pilot
    reports can be accurate or quite inaccurate depending on the pilot and the
    viewing angle, and satellite estimates are most accurate for the larger
    eruptions.

    "The cold-point tropopause generally occurs at around 16-18 km at this time
    of year in Papua New Guinea, and scores of thunderstorms reach these
    altitudes every day in the area. Consequently, it is not surprising that
    the larger eruptions are easily able to reach these altitudes. The
    tropopause is also the major dynamical limit on the rise of the larger
    eruption clouds. The eruption of 27 January clearly penetrated into the
    stratosphere, to altitudes of 21-24 km, based on the warmth of the central
    umbrella cloud, and the subsequent dispersion of the ice-cloud, and the SO2
    from the eruption."

    "All of the eruption clouds have been water/ice rich, and difficult to
    track using satellite techniques. The ash signal at altitudes above the
    freezing level has been overwhelmed by the ice signal in infrared
    split-window imagery. Similarly, in visible and true-colour imagery, even
    where the lower level clouds have shown an ash signal, the higher clouds
    have been a brilliant white and have only been revealed as volcanic in
    short-wave infrared (3.7 um) imagery and with SO2 retrievals. For example,
    [in Bulletin (v. 29, no. 11, the first of two satellite photos)] the large
    brilliant white cloud to the N of Manam (overlying the dark ash cloud)
    derives from the same 24 October eruption."

    Background. The 10-km-wide island of Manam, lying 13 km off the northern
    coast of mainland Papua New Guinea, is one of the country's most active
    volcanoes. Four large radial valleys extend from the unvegetated summit of
    the conical 1807-m-high basaltic-andesitic stratovolcano to its lower
    flanks. These "avalanche valleys," regularly spaced 90 degrees apart,
    channel lava flows and pyroclastic avalanches that have sometimes reached
    the coast. Five small satellitic centers are located near the island's
    shoreline on the northern, southern, and western sides. Two summit craters
    are present; both are active, although most historical eruptions have
    originated from the southern crater, concentrating eruptive products during
    the past century into the SE avalanche valley. Frequent historical
    eruptions have been recorded at Manam since 1616. A major eruption in 1919
    produced pyroclastic flows that reached the coast, and in 1957-58
    pyroclastic flows descended all four radial valleys. Lava flows reached the
    sea in 1946-47 and 1958.

    References: Tupper, A., and Kinoshita, K., 2003, Satellite, air and ground
    observations of volcanic clouds over island of the Southwest Pacific: South
    Pacific Study, v. 23, no. 2, p. 21-46.

    Information Contacts: Andrew Tupper, Darwin Volcanic Ash Advisory Centre,
    Australian Bureau of Meteorology (URL: www.bom.gov.au/info/vaac);
    Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea;
    National Disaster Centre, Department of Provincial Affairs and Local Level
    Government (Ministry of Inter-Government Relations), PO Box 4970, Boroko,
    National Capital District, Papua New Guinea (URL:
    www.pngndc.gov.pg/); The National Online, Lot 13 Section 38, Waigani
    Drive Hohola, PO Box 6817 Boroko, National Capital District, Papua New
    Guinea (URL: www.thenational.com.pg/1206/); Papua New Guinea
    Mapserver (Mapu), EDF 8/9 EU-SOPAC Reducing Vulnerability of Pacific ACP
    States Project (see TikiMap map link at URL:
    map.mineral.gov.pg/tiki/tiki-index.php David
    Innes, Flight Safety Office, Air Niugini, P.O.Box 7186, Boroko, Port
    Moresby, National Capital District, Papua New Guinea (Email:
    dinnes@airniugini.com.pg or deejayinnes@yahoo.com, URL:
    www.airniugini.com.pg/); Simon Carn, TOMS Volcanic Emissions Group,
    University of Maryland, 1000 Hilltop Circle, Baltimore, MD 21250, USA
    (Email: scarn@umbc.edu; URL: skye.gsfc.nasa.gov/).


    Rinjani
    Lesser Sunda Islands, Indonesia
    8.42°S, 116.47°E; summit elev. 3,726 m

    Rinjani had increases in some monitored parameters and hazard status during
    this report interval, covering much of 2004 through 30 January 2005. An
    eruption occurred on 1 October 2004. We previously presented a brief
    aviation report concerning an unconfirmed ash cloud from Rinjani in
    September 1995 (Bulletin v. 20, no. 10). In their text associated with
    recent reporting used here, The Directorate of Volcanology and Geological
    Hazard Mitigation (DVGHM) noted that Rinjani's last explosions occurred
    during 4 June 1994-January 1995. Those explosions came from Barujari
    volcano (see Background for morphologic information).

    On 27 September 2004 a DVGHM report noted the decision to increase
    Rinjani's hazard status to Alert Level II (Yellow, on a scale with the most
    hazardous at IV). During the last third of 2004, the number of volcanic and
    tectonic earthquakes had increased. Their increase followed a rise in the
    number of tectonic earthquakes that began 18 August 2004. Tremor registered
    on 23, 24, 25, and 26 September 2004. Tremor amplitudes ranged between 12
    and 13.5 mm, and the duration of the tremor stood between 94 and 290 seconds.

    At 0530 on 1 October 2004 Rinjani clearly erupted. The observation station
    where visual monitoring occurs (Sembalun Lawang) lies in a spot where the
    caldera wall blocks views into the active zone, so a smaller eruption might
    have been missed. The eruption caused authorities to immediately raise the
    hazard status to Alert Level III (Orange). Further details have not emerged
    regarding the initial 1 October eruption. During the next few days of
    eruptions, the lake Segara Anak remained undisturbed.

    During 2-5 October 2004 continued explosions sent ash columns ~300 to 800 m
    above the summit. Gray, thick ash columns drifted to the N. Detonation
    sounds accompanied every explosion. Successive explosions occurred at
    intervals of 5 to 160 minutes. Explosions vented on the NE slope of
    Barujari volcano. Some material also vented from Barujari's peak, however,
    and fell down around its edifice. A press report in the Jakarta Post
    indicated that evacuations were not considered necessary.

    Available monthly seismic data appears in table 2. Seismicity was dominated
    by explosion earthquakes with maximum amplitudes of 30 mm. Explosion and
    emission signals were common during February and March 2004 and became
    absent or unreported after April 2004. Data were unavailable for October
    2004 when known eruptions occurred.

    Table 2. Available seismicity at Rinjani during 10 February 2004 to 30
    January 2005. The symbol " - " means not reported. Courtesy of VSI.

    Date Volcanic A Volcanic
    B Tremor Emission Explosion

    10 Feb 2004 2 -- 20 3 37
    10 Mar 2004 3 3 16 5 32
    10 Apr 2004 -- -- 5 -- 5
    17-23 Jan 2005 20 28 11 -- --
    24-30 Jan 2005 9 34 11 -- --

    During 24 to 30 January 2005, gas plumes remained less than 600 m tall. The
    tremor record had a maximum amplitude of 1.5 mm.

    Background. Rinjani volcano sits on the island of Lombok and rises to 3,726
    m, making it second in height among Indonesian volcanoes, only shorter than
    Kerinci volcano (Sumatra). Rinjani has a steep-sided conical profile when
    viewed from the E, but the W side of this compound volcano is truncated by
    the oval-shaped (6 x 8.5 km) Segara Anak caldera. The caldera's western
    half contains a 230-m-deep lake whose crescentic form results from growth
    of the post-caldera cone Barujari (also written Baru Jari) at the caldera's
    eastern end. Historical eruptions at Rinjani dating back to 1847 have been
    restricted to Barujari cone and consist of moderate explosive activity and
    occasional lava flows that have entered Segara Anak lake.
    Information Contacts: Directorate of Volcanology and Geological Hazard
    Mitigation (DVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (Email:
    dali@vsi.dpe.go.id; URL: www.vsi.esdm.go.id/); The Jakarta Post,
    Indonesia (URL: www.thejakartapost.com/).


    Anatahan
    Mariana Islands
    16.35°N, 145.67°E; summit elev. 788 m
    All times are local (= UTC + 10 hours)

    As discussed in our previous report (Bulletin v. 29, no. 12), Anatahan's
    third historical eruption began on 5 January 2005. Ongoing eruptions
    continued through at least 18 February 2005.

    Anatahan lies in the Commonwealth of the Northern Mariana Islands (CNMI)
    ~120 km N of Saipan and ~320 km N of Guam. The first historical eruption of
    Anatahan began 10 May 2003 (Bulletin v. 28, nos. 4 and 5); after several
    hours of increasing seismicity, a phreatomagmatic eruption sent ash to over
    ~9 km (~30,000 feet) and deposited about 10 million cubic meters of
    material over the island and sea. A small craggy dome extruded in late May
    and was destroyed during explosions on 13 and 14 June, after which the
    eruption ceased. The second historical eruption began about 9 April 2004
    after a week or so of increasing seismicity (Bulletin v. 29, no. 4). That
    eruption primarily comprised Strombolian explosions every minute or so and
    occasionally sent ash up to a few thousand feet. The eruption ended 26 July
    2004.

    Charles Holliday (US Airforce Weather Agency, AFWA) contributed a series of
    remotely sensed images showing plumes in February (table 3, figure 6). The
    plume in the 4 February Terra image (figure 6, top) contains a brownish
    tinge suggesting considerable ash. The Anatahan region was on the western
    edge of the Terra pass. The image contains an artifact reminiscent of
    Venetian blinds (commonly called the bow-tie effect), which arose due to
    pixel replication in the mapping/processing algorithm filling in for
    missing data on the edge of the scan.

    Table 3. A list of some of the satellite images recording Anatahan plumes
    during 3-15 February 2005. Those shown with an asterisk appear in the next
    figure. Date and time are both UTC; for example, 04 Feb 2005 @ 0105 is the
    date and time in UTC, in this example equivalent to 04 Feb 2005 at 1105
    local time. Names affiliated with satellites are as follows: DMSP (Defense
    Meteorological Satellite Program), NOAA (National Oceanic and Atmospheric
    Administration), NASA (National Aeronautics and Space
    Administration). Courtesy of Charles Holliday, U.S. Air Force Weather Agency.

    2005 Time Satellite and type of image
    (UTC) Predominant direction of plume and comments

    03 Feb 2329 DMSP F16 (capturing visible data at 0.3 nanometer
    (nm) wavelength)
    Steam and vog; seen at least 95 NM (~180 km) from
    Anatahan, trending
    slightly E of S.

    04 Feb *0105 NASA TERRA MODIS (250 m resolution)
    Steam and vog; seen for at least 100 NM (~185 km) to
    the S.

    06 Feb 0050 NASA TERRA MODIS (500 m resolution)
    Steam and vog; 100 NM (~185 km) trending to WSW.

    06 Feb 0043 NOAA 17 (visible, 0.5 nm wavelength)
    Steam and vog; 175 NM (~320 km) to SW.

    06 Feb 0335 NASA AQUA MODIS (500 m resolution)
    Steam and vog; 150 NM (~280 km) trending to WSW.

    08 Feb 2226 DMSP F15 (visible, 0.3 nm)
    Steam and vog; 150 NM (~280 km) trending to SW.

    09 Feb 0125 NASA TERRA MODIS (500 m resolution)
    Steam and vog to the SSW; plume length undisclosed.

    09 Feb 0442 NOAA 16 (visible, 0.5 nm and infrared (IR), 0.5 nm)
    Steam and vog; 150 NM (~280 km) trending over a
    sector from SW to WSW.

    09 Feb 2207 DMSP F16 (visible, 0.5 nm)
    Ash and steam for ten's of kilometers; vog at
    greater distances, up to at
    least 130 NM (240 km) WSW.

    10 Feb 0030 NASA TERRA MODIS (250 m resolution)
    Ash and steam nearer volcano, blowing S to SSW;
    region interpreted as vog
    at distances of ten's of kilometers SW of volcano.

    10 Feb 0052 NOAA 17 (0.5 nm)
    Vog visible 220 NM (~410 km) to the WSW.

    10 Feb 0330 NASA AQUA MODIS (500 m resolution)
    Ash and steam nearer volcano, blowing SW; vog at
    distances ~150 NM (~280
    km) WSW of volcano.

    10 Feb 0423 NOAA 16 (IR, 0.5 nm)
    Ash and steam; plume blown 100 NM (185 km) to W and WSW.

    10 Feb 0423 NOAA 16 (visible, 0.5 nm)
    Ash and steam; 475 NM (967 km) trending to WSW.

    10 Feb 2251 DMSP F15 (visible, 0.3 nm)
    Ash and steam for ten's of kilometers WSW from
    Anatahan; vog at greater
    distances visible up to at least 475 NM (967 km)
    from the volcano.

    11 Feb 0110 NASA TERRA MODIS (1 km resolution)
    One of the longer-extended plumes identified in this
    set, trending SW and
    reaching 525 NM (~972 km) from source to
    identified vog near the SW
    corner of the image. Ash and steam to ten's of
    kilometers from source.

    11 Feb 0412 NOAA 16 (0.5 nm)
    Ash and steam plume that gradually broadens as it
    drifts WSW. The plume was
    ultimately identified as vog in the more distal
    areas. Total length
    identified 505 NM (936 km).

    11 Feb 0415 NASA AQUA MODIS (500 m resolution)
    Plume clearer than on most other images in this set,
    with few weather
    clouds obscuring; SW-directed plume identified as
    ash and steam near
    source; vog in distal areas to ~150 NM (~280 km).

    11 Feb 0702 GOES-9 (visible)
    Longest-extending plume of this set; ash and steam
    WSW of volcano; vog
    detected at 850 NM (~1,600 km) from Anatahan.

    12 Feb 0401 NOAA 16 (visible, 0.3 nm)
    W-directed plume with ash/steam near source, vog at
    355 NM (657 km).

    12 Feb 2316 DMSP F16 (visible, 0.3 nm)
    SW-directed plume, ~140 NM long (~260 km).

    13 Feb 0100 NASA TERRA MODIS (500m resolution)
    SW-directed plume, ~200 NM (~370 km) long.

    13 Feb 0124 NOAA 17 (visible, 0.5 nm)
    W-directed plume, ~360 NM long (~670 km).

    13 Feb 1229 NOAA 17 IR (0.5 nm)
    WNW-directed plume, 95 NM (180 km) long.

    13 Feb *2303 DMSP F16 (visible, 0.3 nm)
    SW-directed plume, ash and steam for much of 140 NM
    (260 km) length
    (unusually clear conditions).

    14 Feb 0101 NOAA 17 IR (0.5 nm)
    Elongate ash-and-steam plume stretched SW to ~120 NM
    (~220 km).

    14 Feb 0101 NOAA 17 (visible, 0.5 nm)
    Ash and steam plume(s) near source; vog visible on
    image to over 400 NM
    (740 km).

    14 Feb 0305 NASA AQUA MODIS (250m resolution)
    SSW-directed plume with ash and steam, but length
    undisclosed.

    14 Feb 0519 NOAA 16 (visible, 0.5 nm)
    W-directed ash-and-steam plume in the near source,
    vog seen ~500 NM
    (~930 km) to the W.

    15 Feb 0038 NOAA 17 (visible, 0.5 nm)
    Gravity waves to the W for 25 NM (~45 km); faint vog
    seen to ~80 km
    (~150 km).

    15 Feb 0045 NASA TERRA MODIS (500 m resolution)
    (Similar to above)

    15 Feb 0350 NASA TERRA MODIS (1 km resolution)
    Ash and steam ~350 NM to the W to SW; faint vog in
    more distal areas.

    15 Feb 0507 NOAA 16 (visible, 0.5 nm)
    Plume directed WSW stretching 345 NM (640 km).

    15 Feb 0812 NOAA 15 (IR, 0.5 nm)
    Ash and steam directed WSW stretching 175 NM (326 km).

    Figure 6. Two remotely sensed images of Anatahan plumes during February
    2004 (N is upwards). (top) S-blown steam and vog on 4 February at 0105 UTC
    clearly identifiable to Saipan and Tinian islands; reported as the source
    of health problems in Guam news reports (see text). (bottom) A modest
    ash/steam plume in unusually clear conditions, imaged at 2303 UTC on 13
    February (DMSP F16 visible) reached 260 km (140 NM). Courtesy of Charles
    Holliday, U.S. Air Force Weather Agency.

    Randy White of the U.S. Geological Survey noted that the energy release
    from seismic stations monitoring Anatahan dropped to near zero on 13
    February 2005, yet a monitoring microphone continued to indicate
    considerable acoustic-energy release. Corresponding to this, a MODIS image
    clearly showed ash still being emitted early on 14 February (see table 3).
    In other words, the seismicity failed to accurately portray the eruption's
    vigor.
    Reporters Katie Worth and Natalie Quinata wrote in the 5 February 2004
    issue of the Pacific Daily News that many students in school on Guam had
    been sent home after experiencing dizziness or nausea because of the
    foul-smelling 'vog' or volcanic smog hovering over the island from the
    eruption. Guam lies ~320 km S of Anatahan.

    John Ravelo wrote a news article for the Saipan Tribune published on 15
    February with the title "Anatahan ash cloud continues to hinder flights."
    Ravelo said that, "An aircraft coming from Manila to Saipan experienced
    zero visibility before landing at the Francisco C. Ada-Saipan International
    Airport yesterday morning, prompting the carrier's pilots to fly around the
    island and search for a clearer approach to the runway. The passenger
    aircraft landed safely at the airport, but the hazy condition delayed its
    arrival."

    At about 0909 on 14 February, the Washington Volcanic Ash Advisory Center
    (VAAC) reported that a plume of ash extended SW of the volcano at an
    altitude of 4.3 km. The plume was 18-28 km wide. Later in the afternoon,
    the Washington VAAC reported an ash plume below an altitude of 2.7 km that
    extended SW of the volcano for about 460 km. The VAAC also forecasted that
    the plume would shift to a more westerly direction within the next 12 hours.

    According to Ravelo's 15 February Saipan Tribune article, the CNMI
    Emergency Management Office and the U.S. Geological Survey "said in a joint
    report that the magnitude of the volcanic eruption declined during the past
    few days." During the eruption's peak on 26 January and 1 February 2005,
    however, the article stated that both agencies noted that the volcano sent
    ash to about 4.6-6.1 km altitude.

    A message from Holliday filed at 0100 UTC on 17 February 2005 included a
    series of remarks, mainly from unnamed scientists on the scene in the
    field. As background prior to presenting those remarks, we note that the
    term 'RSAM' (real-time seismic amplitude) signifies estimates the average
    amplitude of ground shaking. RSAM values increase with increases in tremor
    amplitude or the rate of occurrence and size of earthquakes. The RSAM
    estimates the seismicity during intervals when many earthquakes might
    occur, times when rapid earthquake-magnitude assessments might become
    impractical. The remarks follow.

    "Over the past 24 hours, the eruptive activity at Anatahan apparently
    continued to decline, with RSAM levels at the seismic station ANAT now only
    marginally above the levels recorded just before the 5 January eruption
    began. Microphone amplitudes have also dropped to similar levels.

    "The 2003 crater floor is now essentially entirely covered by fresh lava
    [with] a diameter of about one kilometer. The current eruption peaked
    during the period between 26 January and 2 February [2005], during which
    the volcano sent ash as high as 15,000 to 20,000 feet a.s.l. [~5,000 to
    ~6,000 m] . . .. In the days following, ash blew as far as 100 nautical
    miles [185 km] and vog blew nearly 600 [nautical] miles [~1,100 km] downwind.

    "The third historical eruption of Anatahan began on 5 January, after three
    days of precursory seismicity. On 6 January frequent strombolian explosion
    signals began and by the next day ash was rising to 10,000 feet [~3 km] and
    blowing 40 nautical miles [72 km] downwind. Bombs a meter in diameter were
    being thrown hundreds of feet in the air [ 1 foot = 0.305 m]. By January 20
    explosions were occurring every 3 to 10 seconds and fresh ejecta and small
    lava flows had filled the innermost crater to nearly the level of the
    pre-2003 East Crater floor.

    "The Emergency Management Office, Office of the Governor, CNMI, has placed
    Anatahan Island off limits until further notice and concludes that,
    although the volcano is not currently dangerous to most aircraft within the
    CNMI airspace, conditions may change rapidly, and aircraft should pass
    upwind of Anatahan or beyond 30 km downwind from the island and exercise
    due caution within 30 km of Anatahan."

    Background. The elongated, 9-km-long island of Anatahan in the central
    Mariana Islands consists of two coalescing volcanoes with a 2.3 x 5 km,
    E-trending summit depression formed by overlapping summit calderas. The
    larger western caldera is 2.3 x 3 km wide and extends eastward from the
    summit of the western volcano, the island's 788-m-high point. Ponded lava
    flows overlain by pyroclastic deposits fill the caldera floor, whose SW
    side is cut by a fresh-looking smaller crater. The summit of the lower
    eastern cone is cut by a 2-km-wide caldera with a steep-walled inner crater
    whose floor is only 68 m above sea level. Sparseness of vegetation on the
    most recent lava flows on Anatahan indicated that they were of Holocene
    age, but the first historical eruption of Anatahan did not occur until May
    2003, when a large explosive eruption took place forming a new crater
    inside the eastern caldera.

    Information Contacts. Charles Holliday, U.S. Air Force Weather Agency
    (AFWA), Offutt Air Force Base, Nebraska 68113, USA (Email:
    Charles.Holliday@afwa.af.mil); Randy White, U.S. Geological Survey, 345
    Middlefield Road, Menlo Park, CA 94025-3591 USA (Email: rwhite@usgs.gov);
    Katie Worth and Natalie Quinata, Guam Pacific Daily News, P.O. Box DN,
    Hagatna, Guam 96932, USA (URL: www.guampdn.com/, Email:
    kworth@guampdn.com); John Ravelo, Saipan Tribune (15 February 2005), PMB
    34, Box 10001, Saipan, MP 96950, USA (URL: www.saipantribune.com/);
    Operational Significant Event Imagery (OSEI) team, World Weather Bldg.,
    5200 Auth Rd Rm 510 (E/SP 22), NOAA/NESDIS, Camp Springs, MD 20748, USA
    (URL: www.osei.noaa.gov/, Email: osei@noaa.gov); Washington Volcanic
    Ash Advisory Center (VAAC), Satellite Analysis Branch, NOAA/NESDIS E/SP23,
    NOAA Science Center Room 401, 5200 Auth Road, Camp Springs, MD 20746 USA
    (URL: www.ssd.noaa.gov/).


    Asama
    Honshu, Japan
    36.40°N, 138.53°E; summit elev. 2,560 m
    All times are local (= UTC + 9 hours)

    Setsuya Nakada and Yukio Hayakawa provided follow-up information on events
    at Asama since our last report (Bulletin v. 30, no. 1). Asama's largest
    recent explosion occurred on 1 September 2004, and the second largest, on
    14 November 2004. Subsequent eruptions have been absent except for a small
    one in early December 2004.

    The eruption that started on 1 September 2004 was characterized by an
    increase in the number of A-type earthquakes occurring during and after the
    main phase of explosions (based on data collected by the University of
    Tokyo's Earthquake Research Institute (ERI) and the Japan Meteorological
    Agency). Deep seismicity peaked at the end of 2004, but had subsequently
    remained moderate. GPS (global positioning system) instruments maintained
    ERI and the Geographical Survey Institute (GSI) disclosed inflation of the
    edifice. This inflationary trend has continued since mid-October 2004.

    ERI undertook detailed analysis of earthquake hypocenters and the pressure
    source for the observed GPS data. This showed the existence of a
    dike-shaped magma reservoir trending WNW-ESE. The reservoir occurred just W
    of the summit and 1-2 km below sea level.

    Around October 2004 the height of the lava filling the summit crater
    reached a maximum. Around that time the dome attained a height just ~70 m
    below the crater's lowest notch (an opening along the N rim). By the end of
    January 2005, in contrast, the center of the lava pool had deepened,
    possibly due to draining of the lava body back into the conduit.

    A sequence of radar images provided glimpses into changeable features
    inside the steamy crater. Two images appear here, from 16 September and 15
    December 2004 (figures 7 and 8). The former shows a flat-looking
    disk-shaped extrusion in the crater. The latter shows that the earlier
    extrusion had by this time become disrupted or perhaps buried.

    Figure 7. Radar image of Asama's summit crater taken from a Cessna airplane
    on 16 September 2004 by the Geographical Survey Institute, Japan. N is up.
    Radiated microwaves were transmitted from the N, at 4,290 m altitude, 2 km
    from the crater, with the off-nadir angle of 55 degrees. Courtesy of the
    Geographical Survey Institute.

    Figure 8. Radar image of Asama's summit crater taken from a Cessna on 15
    December 2004 by the Geographical Survey Institute, Japan. N is up.
    Radiated microwaves were transmitted from the N, 2 km from the crater, with
    the off-nadir angle of 55 degrees. Courtesy of Geographical Survey Institute.

    Strong glowing at the summit was considered to be due to significant
    degassing after the main explosive phase. SO2 flux peaked around October
    (at ~5,000 metric tons a day) and has continued at a relatively high level,
    as much as 2,000 to 3,000 metric tons a day.

    The eruptions emitted andesite (SiO2 ~61%), with high crystallinity, and
    containing partially melted sedimentary and other rock (felsic tuff?). The
    rock chemistry has remained uniform throughout the eruptions of the past
    several thousand years, though the inclusion of melted sedimentary rock was
    absent in products erupted prior to 2004.

    Yukio Hayakawa provided a composite isomass map of 2004 Asama tephra
    deposits (figure 9). By far the largest deposit of the year erupted on 1
    September. The smallest documented deposit occurred on 10 October. Ash
    deposits from activity on 1 September drifted NE, deposits from 16
    September drifted SSE; 23 September, NNE; 29 September, N; 10 October, NE;
    and 14 November, E.

    Figure 9. Isomass map of 2004 Asama tephra deposits erupted during
    September-November 2004. Open circles indicate cities; dots indicate
    sampling points where g/m2 of ash were measured; contours are in the same
    units. Courtesy Yukio Hayakawa.

    Background. Asama, Honshu's most active volcano, overlooks the resort town
    of Karuizawa, 140 km NW of Tokyo. The volcano is located at the junction of
    the Izu-Marianas and NE Japan volcanic arcs. The modern cone of
    Maekake-yama forms the summit of the volcano and is situated east of the
    horseshoe-shaped remnant of an older andesitic volcano, Kurofu-yama, which
    was destroyed by a late-Pleistocene landslide about 20,000 years before
    present (BP). Growth of a dacitic shield volcano was accompanied by
    pumiceous pyroclastic flows, the largest of which occurred about
    14,000-11,000 years BP, and by growth of the Ko-Asama-yama lava dome on the
    east flank. Maekake-yama, capped by the Kama-yama pyroclastic cone that
    forms the present summit of the volcano, is probably only a few thousand
    years old and has an historical record dating back at least to the 11th
    century AD. Maekake-yama has had several major plinian eruptions, the last
    two of which occurred in 1108 and 1783 AD.

    Information contacts: Setsuya Nakada, Volcano Research Center, Earthquake
    Research Institute (ERI), University of Tokyo, Yayoi 1-1-1, Bunkyo-ku,
    Tokyo 113, Japan (Email: nakada@eri.u-tokyo.ac.jp; URL:
    www.eri.u-tokyo.ac.jp/topics/...e.html); Yukio
    Hayakawa, Faculty of Education, Gunma University, Aramaki 4-2, Maebashi
    Gunma 371-8510, Japan (Email: hayakawa@edu.gunma-u.ac.jp, URL:
    maechan.net/hayakawa/asama/gankoran/,
    www.edu.gunma-u.ac.jp/~hayaka...h.html); Geographical Survey
    Institute, Ministry of Land, Infrastructure and Transport, 1, Kitasato,
    Tsukuba-shi, Ibaraki-ken 305-0811 Japan (URL: www.gsi.go.jp; URL
    with radar data (text in Japanese): www.gsi.go.jp/BOUSAI/ASAMA/);
    Japan Meteorological Agency, Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122,
    JAPAN (URL: www.jma.go.jp/ ).


    Shiveluch
    Kamchatka Peninsula, Russia
    56.653 N, 161.360 E; summit elev. 3,283 m
    All times are local (= UTC + 12 hours [+13 hours in March-June])

    The previous report on Shiveluch (Bulletin v. 29, no. 5) covered activity
    until 27 May 2004. From May 2004 until September 2004, seismicity at
    Shiveluch was above background, with many shallow earthquakes recorded 0-5
    km beneath the active lava dome, and Shiveluch remained at Concern Color
    Code Orange. Periods of continuous spasmodic tremor were recorded in May,
    June, July, and October 2004. Gas-and-steam plumes rising to 3-6 km
    altitude were frequent, sometimes drifting up to 10 km or more. A small
    lava flow on top of the active dome, first observed on 21 May, continued to
    flow until 28 May. On 19 June, a likely ash cloud was seen 10-20 km S of
    the volcano. The lava dome continued to grow in Shiveluch's active crater.

    On 6 September at 2054 an explosion produced small pyroclastic flows and an
    ash plume that rose to ~5.5 km altitude. According to satellite data, 1- to
    12-pixel thermal anomalies were registered over the lava dome on 15-16
    September 2004. During 23-29 September, 26 strong shallow earthquakes up to
    M 2.3 were recorded. An explosion on 25 September was accompanied by small
    pyroclastic flows. The Kamchatka Volcanic Eruptions Response Team
    (KVERT),again reported seeing a new lava flow at Shiveluch's lava dome
    around 26 October.

    Based on interpretations of seismic data, possible ash-and-gas explosions
    up to 7 km altitude occurred throughout October (figure 10), November, and
    December 2004. Possible minor ash-and-gas explosions and hot avalanches
    also occurred. On 28 December a gas-and-steam plume extended as far as 50 km E.

    Figure 10. A dark plume of ash streamed from the Shiveluch at 0110 UTC on
    20 October 2004, when the Moderate Resolution Imaging Spectroradiometer
    (MODIS) on NASA's Terra satellite captured this image. MODIS observed
    several such plumes in October. Fainter plume(s) to the SW can be seen from
    Bezymianny or Kliuchevskoi, both of which were emitting ash plumes during
    the first week of October.

    During January and February 2005, seismicity decreased slightly at
    Shiveluch but remained above background levels, with weak shallow
    earthquakes occurring beneath the active dome. Possible weak ash-and-gas
    explosions and hot avalanches occurred throughout January and February, and
    gas-and-steam plumes rose up to 2-7 km altitude.

    On 13 January, several ash explosions up to 5 km altitude and a pyroclastic
    flow probably occurred. The Tokyo Volcanic Ash Advisory Center (VAAC)
    reported an eruption of Shiveluch on 17 January at 1625 with a plume that
    rose to a height of ~4.5 km altitude. On 6 February a pyroclastic flow
    traveled ~2 km down the volcano's flank. On 17 February ash deposits were
    seen on the volcano's snow-covered lava dome extending to the SE and S.

    A large eruption occurred at Shiveluch from 1825 on 27 February to 0100 on
    28 February, leading KVERT to raise the Concern Color Code from Orange to
    Red (the highest level). Meteorological clouds obscured the volcano during
    the eruption. According to satellite data (NOAA 16 at 1656 UTC on 27
    February), a 45-pixel thermal anomaly was registered near the dome (band
    3). This anomaly was probably related to a large pyroclastic flow on the SW
    flank. At this time analysts detected a 45-km-long ash cloud on satellite
    imagery trending NW of the volcano. At 0900 on the 28th, ash deposits were
    noted in the town of Klyuchi, ~46 km from the volcano. Satellite imagery
    from 1205 on 28 February showed ash deposits W of Shiveluch covering an
    area of 24,800 km^2. Later that day, an ash cloud extending more than 360
    km was centered over the western half of Kamchatka. On 1 March the Concern
    Color Code was reduced to Orange. Prior to the 27 February eruption,
    seismicity was above background levels and ash-and-gas plumes were seen on
    video rising to ~3 km above the lava dome.

    Explosions deposited ash in Ust'-Hairyuzovo village, about 250 km to the W,
    on 27 and 28 February, and on 2 March. The seismic station at Shiveluch
    stopped working on 27 February. According to visual and video data on 2
    March, part of a large pyroclastic flow was observed on the SW flank of the
    volcano. According to satellite data from the USA and Russia, a 2- to
    23-pixel thermal anomaly was registered at the dome on 1-3 March. Clouds
    obscured the volcano at other times. Shiveluch remained at Concern Color
    Code Orange.

    Background. The high, isolated massif of Shiveluch volcano (also spelled
    Sheveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group.
    The 1,300 km^3 Shiveluch is one of Kamchatka's largest and most active
    volcanic structures. The summit of roughly 65,000-year-old Strary Shiveluch
    is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the
    S. Many lava domes dot its outer flanks. The Molodoy Shiveluch lava dome
    complex was constructed during the Holocene within the large
    horseshoe-shaped caldera; Holocene lava dome extrusion also took place on
    the flanks of Strary Shiveluch. At least 60 large eruptions of Shiveluch
    have occurred during the Holocene, making it the most vigorous andesitic
    volcano of the Kuril-Kamchatka arc. Widespread tephra layers from these
    eruptions have provided valuable time markers for dating volcanic events in
    Kamchatka. Frequent collapses of dome complexes, most recently in 1964,
    have produced debris avalanches whose deposits cover much of the floor of
    the breached caldera.

    Information Contacts: Olga A. Girina, Kamchatka Volcanic Eruptions Response
    Team (KVERT), a cooperative program of the Institute of Volcanic Geology
    and Geochemistry, Far East Division, Russian Academy of Sciences, Piip Ave.
    9, Petropavlovsk-Kamchatskii 683006, Russia (Email: girina@kcs.iks.ru), the
    Kamchatka Experimental and Methodical Seismological Department (KEMSD), GS
    RAS (Russia), and the Alaska Volcano Observatory (USA); Alaska Volcano
    Observatory (AVO), a cooperative program of the U.S. Geological Survey,
    4200 University Drive, Anchorage, AK 99508-4667, USA (URL:
    www.avo.alaska.edu/; Email: tlmurray@ usgs.gov), the Geophysical
    Institute, University of Alaska, P.O. Box 757320, Fairbanks, AK 99775-7320,
    USA (Email: eisch@dino.gi.alaska.edu), and the Alaska Division of
    Geological and Geophysical Surveys, 794 University Ave., Suite 200,
    Fairbanks, AK 99709, USA (Email: cnye@giseis.alaska.edu); Tokyo Volcanic
    Ash Advisory Center, Tokyo Aviation Weather Service Center, Haneda Airport
    3-3-1, Ota-ku, Tokyo 144-0041, Japan
    (www.jma.go.jp/JMA_HP/jma/...index.html).


    Veniaminof
    Alaska Peninsula, USA
    56.17°N, 159.38°W; summit elev. 2,507 m
    All times are local = UTC - 9 / 8 hours (winter / summer)

    After a long period of quiescence, Veniaminof began exhibiting increased
    seismicity and possible low-level eruptive activity from September 2002
    through mid-April 2003. Between mid-April 2003 and February 2004 no signs
    of activity were observed. From February 2004 until the end of June 2004
    steam and ash emissions were observed and volcanic tremor and earthquakes
    recorded (Bulletin v. 29, no. 6).

    Activity during July 2004. Throughout July 2004 short intervals of volcanic
    tremor continued. Small amounts of dark ash were seen in the ice-filled
    caldera on 27 June. During the second week of July, the Alaska Volcano
    Observatory (AVO) reported that the tremor correlated well with
    ash-and-steam plumes as high as 1.5 km altitude; during the rest of the
    month, these plumes may have reached as high as 3.7 km altitude. On 22 July
    at 1229, an AVO field crew witnessed a small ash burst rise a few hundred
    meters above the summit of the intracaldera cone (figure 11). This type of
    activity had prevailed at Veniaminof during the previous three months.
    During the last week of July, the cone produced variable amounts of white
    steam from at least two separate craters near its top. The snow-and-ice
    field over much of the caldera was covered with a discontinuous, 1- to 2-mm
    thick ash blanket. No visual observations of ash emissions were made after
    22 July, although the recorded seismicity was similar to that observed
    during ash emissions in the previous few months. Veniaminof remained at
    Concern Color Code Yellow throughout July.

    Figure 11. Veniaminof's intracaldera cone photographed on 22 July 2004 in a
    view to the SW. The ~330-m-high intracaldera cinder and spatter cone was
    the source of all known historical Veniaminof eruptions. The cone protrudes
    through glacial ice that fills the summit caldera. Although this photo was
    taken during an interval with occasional minor ash and steam emissions, at
    this moment only steam rises to a few hundred meters above the cone. A very
    faint dusting of ash has discolored the glacier's surface; however, some
    may be older, wind-blown ash rather than freshly erupted ash. Courtesy of
    K.L. Wallace, USGS.

    Activity during August 2004. Episodes of volcanic tremor continued
    throughout August. No visual observations of ash emissions were made from
    22 July through the first week of August, although the recorded seismicity
    was similar to that observed during ash emissions in the previous weeks.
    Throughout the month, frequent small ash-and-steam emissions from
    Veniaminof were visible on the web camera in Perryville and confirmed by
    AVO geologists working in the area. Bursts of volcanic tremor recorded
    intermittently on 17 August were probably associated with low-level,
    short-term ash emissions. Veniaminof remained at Concern Color Code Yellow
    throughout August 2004.

    Activity during September 2004. During the first three weeks of September
    both low-level tremor and intermittent bursts of tremor continued at
    Veniaminof. AVO scientists believed tremor episodes likely represented
    low-level ash-and-steam emissions similar to those observed during the
    previous two months. Minor emissions of ash and steam were occasionally
    seen on the web camera during clear weather. During the last week of
    September, low-level tremor and intermittent small tremor bursts may have
    occurred at Veniaminof, but high winds in the area caused considerable
    vibrational noise, masking the signal of interest, and making analysis of
    seismic records inconclusive. The winds were strong enough to hide evidence
    of low-level tremor. If the tremor episodes continued, they likely
    corresponded with low-level ash-and-steam emissions similar to those
    observed over the previous four months. Cloudy conditions obscured views of
    the volcano by web camera and satellite. Veniaminof remained at Concern
    Color Code Yellow throughout September.

    Activity during October 2004. Low-level seismic tremor and intermittent
    small tremor bursts continued. These tremor episodes likely represented
    low-level ash and steam emissions similar to those observed over the past
    four months, although cloudy conditions obscured views of the volcano by
    web camera and satellite.

    Low-level tremor during 8-15 October correlated with weak steaming of the
    intracaldera cone as observed on the web camera. No ash emissions were
    observed, although cloudy conditions over the caldera restricted viewing
    for much of the week. AVO lowered the Concern Color Code at Veniaminof on
    26 October from Yellow to Green. Seismicity, which had been associated with
    ash emissions during the summer of 2004, decreased to levels that indicated
    ash, ash-and-steam, or steam emissions were no longer occurring on a
    regular basis. Since early September, no ash emissions were seen on the web
    camera and no evidence of ash was visible on satellite imagery. Also, AVO
    had received no recent reports of ash from pilots or ground observers. AVO
    considered the intermittent, low-level seismic tremor that continued to be
    recorded at the volcano to be part of the background activity.

    Activity during January 2005. AVO raised the Concern Color Code at
    Veniaminof from Green to Yellow on 4 January because around that time
    several small ash emissions from the volcano's intracaldera cone were
    observed on the web camera in Perryville. Ash emissions were visible
    starting around 0938, but may have been obscured by meteorological clouds
    in previous images. The discrete ash emissions were small, rose hundreds of
    meters above the cone, and dissipated as they drifted E. Minor ash fall was
    probably confined to the summit caldera. Very weak seismic tremor was
    recorded beginning on 1 January, and increased slightly over the next 2
    days. These seismic signals were similar to those recorded during
    steam-and-ash emissions in April to October 2004. However, there were no
    indications from seismic data that events significantly larger than those
    observed around 4 January were imminent.

    AVO raised the Concern Color Code at Veniaminof from Yellow to Orange on 10
    January as ash emissions from the volcano's intracaldera cone reached
    heights of nearly 4 km during 8-10 January (figure 12). Seismicity remained
    at elevated levels and satellite images showed a persistent thermal anomaly
    at the intracaldera cone. On 11 January, the Anchorage VAAC again reported
    emission of a thin ash cloud to ~3 km altitude visible on the Perryville
    web camera. On 12 January the Anchorage VAAC reported emission of a thin
    ash cloud, visible on the Perryville web camera, that rose to 3-4 km
    altitude, extended ENE, and dissipated within ~55 km of the volcano. On 14
    January, a satellite image showed a thermal anomaly in the vicinity of the
    Veniaminof summit. Although the anomaly appeared less intense than when
    first detected on 8 January and volcanism seemed to have declined
    significantly since 12 January, activity still remained significantly
    higher than normal with occasional bursts of volcanic tremor.

    Figure 12. Veniaminof intracaldera cinder cone, 11 January 2005. The
    elevation of the cone is 2,156 m and the ash plume is drifting to NE. Photo
    taken during an observational overflight. Image courtesy of K.L.Wallace, USGS.

    During the rest of the month of January, seismic data, web camera views,
    and satellite images indicated that low-level ash emissions continued at
    Veniaminof. Seismicity was similar to levels observed during the previous
    week, consisting of low-amplitude volcanic tremor with occasional larger
    bursts. During clear weather, satellite imagery showed anomalous heat at
    the summit cone, consistent with hot blocks and ash being ejected from the
    active vent. In addition, the web camera showed intermittent ash plumes
    reaching as high as 3 km altitude. Occasional stronger bursts of seismic
    tremor during 20-21 January and around 28 January may have indicated plumes
    to higher levels, but not above 4 km altitude. Veniaminof remained at
    Concern Color Code Orange.

    Activity during February 2005. On the evening of 3 February, Strombolian
    activity at Veniaminof was visible by residents of Perryville ~30 km from
    the volcano. Activity was also observed on web camera views and seen by
    satellite as an increase in radiated surface heat. An increase in
    seismicity suggested that Strombolian activity may have continued through 4
    February while the volcano was obscured by clouds.

    During 28 January to 4 February, seismicity at Veniaminof was similar to
    levels for the previous week, with low-amplitude tremor and occasional
    larger bursts. During clear weather, satellite imagery showed anomalous
    heat at the summit cone, consistent with hot blocks and ash being ejected
    from the active vent. The web camera showed intermittent ash plumes
    reaching as high as 3 km altitude. Veniaminof remained at Concern Color
    Code Orange.

    Low-level Strombolian eruptive activity continued at Veniaminof during 4-11
    February. On 9 February, an ash burst rose hundreds of meters above the
    intracaldera cone. Satellite images continued to show a thermal anomaly in
    the vicinity of the intracaldera cone, consistent with the presence of hot
    material at the vent. Seismicity remained above background levels at the
    volcano. On the morning of 10 February there was a distinct increase in the
    amplitude and frequency of earthquakes. The increase continued through 11
    February. This activity was consistent with more energetic explosions from
    the active cone, but there were no indications that the bursts rose higher
    than 4 km altitude. Veniaminof remained at Concern Color Code Orange.

    During 11-18 February, it was likely that low-level Strombolian eruptive
    activity continued at Veniaminof based on seismic data and satellite
    imagery. Cloudy conditions obscured web camera views of the volcano, and no
    ash emissions were observed above the cloud cover. Seismicity remained
    above background levels at Veniaminof. The character of the seismicity
    changed slightly during the report period, with frequent periods of
    continuous banded volcanic tremor occurring, but the amplitudes of
    earthquakes did not increase. This activity was consistent with explosions
    from the active cone; however, there was no indication that these bursts
    rose more than 4 km altitude. Veniaminof remained at Concern Color Code Orange.

    Seismicity decreased substantially at Veniaminof during 18-25 February in
    comparison to previous weeks, leading AVO to decrease the Concern Color
    Code from Orange to Yellow. Periods of volcanic tremor diminished, and no
    discrete events associated with ash bursts had occurred for several days.
    Only minor steam emissions were seen. AVO received no reports of ash
    emissions from pilots or ground observers. AVO concluded that given the
    decline in seismicity, it appeared that the most recent episode of
    Strombolian eruptive activity at Veniaminof had ended.

    Activity during March 2005. A further reduction in activity at Veniaminof
    during 25 February to 4 March led AVO to reduce the Concern Color Code from
    Yellow to Green, the lowest level. For more than a week seismic activity
    was at background levels, periods of volcanic tremor had ceased, and there
    were no discrete events associated with ash bursts. Only minor emissions of
    steam were observed on the web camera and satellite imagery. AVO received
    no reports of ash emissions from pilots or observers on the ground. They
    concluded that given the decline in seismicity it appeared that the most
    recent episode of eruptive activity had ended at Veniaminof.

    Background. Massive Veniaminof volcano, one of the highest and largest
    volcanoes on the Alaska Peninsula, is truncated by a steep-walled, 8 x 11
    km, glacier-filled caldera that formed around 3,700 years ago. The caldera
    rim is up to 520 m high on the N, is deeply notched on the W by Cone
    Glacier, and is covered by an ice sheet on the S. Post-caldera vents are
    located along a NW-SE zone bisecting the caldera. That zone extends 55 km
    from near the Bering Sea, across the caldera, and down the Pacific flank.
    Historical eruptions probably all originated from the westernmost and more
    prominent of two intra-caldera cones, which reaches an elevation of 2,156 m
    and rises about 300 m above the surrounding icefield. The other cone is
    larger, and has a summit crater or caldera that may reach 2.5 km in
    diameter, but is more subdued and barely rises above the glacier surface.

    Information Contacts: Alaska Volcano Observatory (AVO), a cooperative
    program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK
    99508-4667, USA (URL: www.avo.alaska.edu/; Email:
    tlmurray@usgs.gov), b) Geophysical Institute, Univ. of Alaska, P.O. Box
    757320, Fairbanks, AK 99775-7320, USA (Email: eich@dino.gi.alaska.edu), and
    c) Alaska Division of Geological & Geophysical Surveys, 794 University
    Ave., Suite 200, Fairbanks, AK 99709, USA (Email: cnye@giseis.alaska.edu);
    Kristi L. Wallace, USGS/AVO, Alaska Tephra Laboratory and Data Center, 4230
    University Drive, Suite 201, Anchorage, AK 99508, USA (Email:
    kwallace@usgs.gov).


    St. Helens
    Washington, USA
    46.20°N, 122.18°W; summit elev. 2,549 m
    All times are local ( = UTC - 8 hours)

    Growth of the new lava dome inside the crater of Mount St. Helens has
    continued since the last report (Bulletin v. 29, no. 10), accompanied by
    low rates of seismicity, low emissions of steam and volcanic gases, and
    minor production of ash. During such eruptions, episodic changes in the
    level of activity can occur over days to months. The eruption can also
    intensify suddenly or with little warning and produce explosions that may
    cause hazardous conditions within several kilometers of the crater and
    farther downwind. The current status is Volcano Advisory (Alert Level 2),
    and the aviation color code is orange.

    A small, short-lived explosive event at St. Helens volcano began at
    approximately 1725 hours on 8 March 2005. Airplane pilot reports indicated
    that the resulting steam-and-ash plume reached an altitude of about 11 km
    above sea level within a few minutes and drifted NE.

    Results from analysis of imagery by the U.S. Geological Survey of 21
    February 2005 showed that the highest part of the new lava dome stands at
    an altitude of 2.3 km, 160 m higher than the old lava dome, and only 28 m
    below Shoestring Notch, a low point on the SE crater rim. Further analysis
    of recent aerial photos revealed that as of 1 February, the
    whaleback-shaped dome extrusion was about 470 m long and 150 m wide. The
    new dome and uplifted welt of crater floor and deformed glacier ice have
    grown to a combined volume of about 38 million m3, almost one-half the
    volume of the old lava dome.

    Background. Prior to 1980, Mount St. Helens formed a conical, youthful
    volcano sometimes known as the Fuji-san of America. During the 1980
    eruption the upper 400 m of the summit was removed by slope failure,
    leaving a 2 x 3.5 km horseshoe-shaped crater now partially filled by a lava
    dome. Mount St. Helens was formed during nine eruptive periods beginning
    about 40-50,000 years ago and has been the most active volcano in the
    Cascade Range during the Holocene. Prior to 2,200 years ago, tephra, lava
    domes, and pyroclastic flows were erupted, forming the older St. Helens
    edifice, but few lava flows extended beyond the base of the volcano. The
    modern edifice was constructed during the last 2,200 years, when the
    volcano produced basaltic as well as andesitic and dacitic products from
    summit and flank vents. Historical eruptions in the 19th century originated
    from the Goat Rocks area on the N flank, and were witnessed by early settlers.

    Information Contacts: Cascades Volcano Observatory (CVO), U.S. Geological
    Survey, 1300 SE Cardinal Court, Building 10, Suite 100, Vancouver, WA
    98683-9589, USA (URL: vulcan.wr.usgs.gov/; Email:
    GS-CVO-WEB@usgs.gov); Pacific Northwest Seismograph Network (PNSN),
    Seismology Lab, University of Washington, Department of Earth and Space
    Sciences, Box 351310, Seattle, WA 98195-1310, USA (URL:
    www.pnsn.org/; Email: seis_info@ess.washington.edu).


    Kick 'em Jenny
    Grenada, West Indies
    12.30°N, 61.64°W; summit elev. -185 m

    The University of West Indies Seismic Research Unit (SRU) has augmented
    their instrumental monitoring network and warning system at Kick 'em Jenny
    submarine volcano. In addition to long-period and broadband seismometers to
    sense earthquakes, they have also employed tide gauges to measure seawater
    disturbances, hydrophones to discern submarine explosions, and tilt meters
    and global positioning system (GPS) stations to detect long-term ground
    deformation. The instruments may disclose anomalies and critical symptoms
    before an eruption begins. Various combinations of these instruments were
    installed at Mt. St. Catherine, Sauteurs, The Sisters Rocks, Isle de Ronde,
    Isle de Caille, and Carriacou (figure 13).

    Figure 13. A map indicating positions of monitoring instruments for the
    current network at Kick 'em Jenny. Tilt meters and tide gauges were not
    functioning at the time of this writing (early 2005). (Inset) Grenada and
    Carriacou islands lie at the S end of the West Indies. Courtesy of SRU.

    The NSF Caribbean Tsunami Workshop was held in March 2004 (Mercado-Irizarry
    and Liu, 2004). The Workshop's program ended its Introduction section with
    this statement: " . . . Kick 'em Jenny, close to the islands of the
    southeastern Caribbean (just 10 km N of Grenada), is of much concern to the
    local governments. Past eruptions during the last century (1939, 1965)
    resulted in observed deep water tsunamis, with the one in 1939 being
    measured as 1 m high [Shepherd, 2001]. The concern is such that, for the
    first time (at least in the region), a banking institution (the Caribbean
    Development Bank) is funding a monitoring program [at] the volcano."

    A 29 December 2004 article entitled "Tsunami warning system for the
    Caribbean," posted on the SRU website, also addressed the issue. It noted
    that, "The devastation caused by the tsunami which ravaged several Asian
    countries on 26th December 2004 has sparked discussion on the importance of
    a tsunami early warning system in the Caribbean. While in theory such a
    system may seem invaluable in light of the Asian disaster, scientists at
    the Seismic Research Unit currently believe that several factors should be
    seriously considered before assuming that a tsunami early warning system
    would be beneficial to the region. Head of the Seismic Research Unit, Dr.
    Richard Robertson, says that 'Before the region spends valuable resources
    on setting up new instruments for a tsunami early warning system, we need
    to strengthen our existing networks and focus on improving public education
    and communication activities with regard to geologic hazards in the region.'"

    Gas release, T-phase seismicity, and minor eruption clouds. The question of
    whether or not there is strong fumarolic activity in the crater has been a
    source of speculation for a number of years. It has been suggested that
    warmed water rising in convection currents contributed to the reputation of
    the Kick 'em Jenny region for rough water. The emission of large quantities
    of bubbles was observed in 1989 when the submersible Johnson Sealink
    entered the crater a few months after the 1988 eruption (Bulletin v. 14,
    no. 5).

    A water column containing a significant proportion of rising gas bubbles
    results in a local lowering of the seawater's density. (The rising bubbles
    displace some of the sea water, and at or near the sea surface they provide
    negligible support to the ship, thus resulting in a loss of buoyancy for
    ships passing over the volcano.) To account for this hazard, and the risk
    posed by ejecta, an exclusion zone 1.5 km in radius was created over the
    volcano (Shepherd, 2004).

    At least 11 historical episodes of hydro-acoustic (T phase) signals have
    been detected since 1939 when an eruption cloud rose 275 m above the sea
    surface (Shepherd and Robson, 1967, Smith and Shepherd, 1995, Lindsay et
    al., 2005). Material was also ejected during the 1974 eruption, and the
    1988 eruption was associated with turbulent discolored water (Lindsay and
    others, 2005). Some of these were described in Smithsonian reports dating
    back to 1977.

    Regarding T-Phase waves. A short-period wave group from a seismic source
    that has propagated in part through the ocean is called T-phase or
    T(ertiary)-wave (Linehan, 1940; Tolstoy and Ewing, 1950; Walker and
    Hammond, 1998). The wave group propagates with low attenuation as
    hydro-acoustic (compressional) waves in the ocean, constrained within a low
    sound-speed wave guide (the sound fixing and ranging-SOFAR-channel) formed
    by the sound-speed structure in the ocean. The T-phase signal may be picked
    up by hydrophones in the ocean or by land seismometers. Upon incidence with
    the continental shelf/slope, the wave group is transformed into ordinary
    seismic waves that arrive considerably later than seismic wave groups from
    the same source that propagated entirely through the solid Earth.

    2002 and 2003 Surveys. A 2003 oceanographic survey of Kick 'em Jenny was
    conducted jointly by the National Oceanic and Atmospheric Agency (NOAA),
    SRU, and the University of Rhode Island (URI) using the NOAA Research
    Vessel Ronald H. Brown. This survey supplemented data obtained previously
    from a cruise passing the volcano on 12 March 2002 (Bulletin v. 27, no. 6).
    That effort produced the bathymetric image shown in Bulletin v. 27 no. 6
    and reproduced here as figure 14. The arcuate scarp on the image suggested
    that the volcano was once the scene of sector collapse. The inferred
    submarine debris avalanche has an estimated total volume of ~10 km^3, and a
    maximum runout distance of at least 15 km (Sigurdsson and others, 2004;
    Shepherd 2004). The collapse clearly occurred prior to the growth of the
    small central edifice at Kick 'em Jenny. The ages of these various features
    remain unknown.

    Figure 14. Morphology of Kick 'em Jenny, as revealed by a multi-beam survey
    by the NOAA Research Vessel Ronald H. Brown in March 2002 (N is toward the
    top; for approximate scale, the sub-circular summit crater is about ~ 300 m
    in diameter). The survey showed that the volcano's smaller, modern, active
    cone sits nested within a larger U-shaped depression that wraps completely
    around the cone's E side and opens toward the W. This larger depression
    presumably formed by slope failure and generated a W-directed debris
    avalanche that appears to lie within a marginal, confining levee. Courtesy
    of NOAA.

    Figures 15 and 16 highlight the discovery of other volcanic features on the
    sea floor just E of Kick 'em Jenny. Little is known about them aside from
    their basic morphology illuminated by the 2003 survey. Discoveries near
    Kick 'em Jenny included three craters (C1, C2, and the largest, Kick 'em
    Jack) and two domes (D1 and D2). The mutual relations and ages of these
    newly recognized features remain uncertain.

    Figure 15. Vertically exaggerated SeaBeam image of Kick 'em Jenny and newly
    identified craters and domes discovered in March 2003. Kick 'em Jenny's
    summit occurs adjacent to the crater rim at a depth of ~ 185 m. The deepest
    point on Kick 'em Jenny's crater floor lies at ~ 264 m depth. The summit
    sits at 12º18.024' N, 61º38.388' W (12.3004º N, 61.6398º W). The image's
    left side is drawn N-S (i.e. N towards the upper left). Tick marks along
    the margins are at 0.01 degree intervals, a spacing equivalent to 1.8-1.9
    km. The distance between Kick 'em Jenny and Kick 'em Jack is about 4 km. A
    vertical scale at the left indicates water depth: 0, -250, -500, and -750
    m. Courtesy of NOAA and SRU.

    Figure 16. Broad-scale SeaBeam image of Kick 'em Jenny and adjacent
    features compiled from Ronald H. Brown cruise observations, March 2003.
    North is up. The crater rim of Kick 'em Jenny ("rim"), as well as the rest
    of the body of that dome, lie within a larger arcuate scarp that wraps
    around the dome's E side. On the dome's W side the scarp extends outward,
    crossing a swath of sea floor as two sub-parallel arms (indicated by the
    arrows). Kick 'em Jack lies well outside this scarp, ~ 4 km SE of Kick 'em
    Jenny. Courtesy of NOAA and SRU.

    Background. Kick 'em Jenny, a historically active submarine volcano 8 km
    off the N shore of Grenada, rises 1,300 m from the sea floor. The volcano
    is located on the steep inner western slope of the Lesser Antilles
    submarine ridge facing the Grenada Basin. Recent bathymetric surveys have
    shown evidence for a major arcuate collapse structure that was the source
    of a submarine debris avalanche that traveled more than 15 km to the W.
    Numerous historical eruptions, mostly documented by acoustic signals, have
    occurred since 1939, when an eruption cloud rose 275 m above the sea
    surface. Prior to the 1939 eruption, which was witnessed by a large number
    of people in northern Grenada, there had been no written mention of Kick
    'em Jenny. Eruptions have involved both explosive activity and the quiet
    extrusion of lava flows and lava domes in the summit crater; deep rumbling
    noises have sometimes been heard onshore. Historical eruptions have
    modified the morphology of the summit crater.

    References: Linehan, D., 1940, Earthquakes in the West Indian region:
    Transactions, American Geophysical Union, Pt. II, p. 229-232.

    Mercado-Irizarry, A., and Liu, P. L.-F., 2004, NSF Caribbean Tsunami
    Workshop, 30-31 March 2004: San Juan Beach Hotel, San Juan, P.R.,
    sponsored by the U. S. National Science Foundation, Puerto Rico State
    Emergency Management Agency, Department of Marine Sciences at the
    University of Puerto Rico at Mayaguez, and the Sea Grant Program at the
    University of Puerto Rico.

    Lindsay, J. M., Shepherd, J.B., and Wilson D., 2005, Volcanic and
    scientific activity at Kick 'em Jenny submarine volcano 2001-2002:
    Implications for volcanic hazard in the Southern Grenadines, Lesser
    Antilles: Natural Hazards, v. 31, p. 1-24.

    Shepherd, J.B., and Robson, G.R., 1967, The source of the T-phase recorded
    in the Eastern Caribbean on October 24, 1965: Bull. Seismol. Soc. Amer.,
    v. 57, p. 227-234.

    Shepherd, J.B., 2001, Marine and coastal hazards from Kick 'em Jenny
    submarine volcano, southern Grenadine Islands (copyrighted slide-show
    presentation): URL:
    www.uwichill.edu.bb/bnccde/g...nny.html.

    Shepherd, J.B., 2004, Report on studies of Kick 'em Jenny submarine volcano
    March 2002 and March 2003 with updated estimates of marine and coastal
    hazards: The University of the West Indies Seismic Research Unit, KEJ
    Report Feb 2004, St. Augustine, Trinidad and Tobago, West Indies, 44 p.

    Sigurdsson, H., Carey, S., and Wilson, D., 2004, Debris avalanche formation
    at Kick 'em Jenny submarine volcano, in NSF Caribbean Tsunami Workshop,
    30-31 March 2004, San Juan Beach Hotel, San Juan, P.R. (URL:
    nsfctw.uprm.edu/agenda.html).

    Smith, M., and Shepherd, J., 1995, Potential Cauchy-Poisson waves generated
    by submarine eruptions of Kick 'em Jenny volcano: Natural Hazards, v. 11,
    p. 75-94.

    Tolstoy, I., and Ewing, M., 1950, The T phase of shallow-focus earthquakes:
    Bulletin of the Seismological Society of America, v. 40, p. 25-51.

    Walker, D.A., and Hammond, S.R., 1998, Historical Gorda Ridge T-phase
    swarms; relationships to ridge structure and the tectonic and volcanic
    state of the ridge during 1964-1966: Deep-Sea Research Part II, v. 45, n.
    12, p. 2531-2545.

    Information Contacts: Seismic Research Unit (SRU), The University of the
    West Indies, St. Augustine, Trinidad & Tobago, West Indies (URL:
    www.uwiseismic.com); Research Vessel Ronald H. Brown, National
    Oceanic and Atmospheric Agency (NOAA), Marine Operations Center, Atlantic,
    439 West York Street, Norfolk, VA 23510-1145, USA (URL:
    oceanexplorer.noaa.gov/explorations/).


    Marion Island
    Southern Indian Ocean, South Africa
    46.90°S, 37.75 E; summit. elev 1,230 m

    A small volcanic eruption was observed on 24 June 2004 by a member of the
    South African National Antarctic Programme's (SANAP) over-wintering team on
    Marion Island (figure 17). While conducting fieldwork in a mountainous area
    on the S part of the island, David Heddings was able to video an eruption
    that comprised gas and small pieces of scoria (a few centimeters in diameter).

    Figure 17. The SANAP base station, located on the E side of Marion Island.
    Courtesy of Ian Meiklejohn.

    While it has been assumed that small volcanic eruptions often take place on
    Marion Island, the remoteness and hilly terrain over much of the island has
    meant that such events have not been witnessed. The last confirmed eruption
    on Marion took place in 1980 when ornithologists found a fresh basaltic
    lava flow on the W side of the Island.

    Background. Marion Island, South Africa's only historically active volcano,
    lies at the SW end of a submarine plateau immediately south of the SW
    Indian Ocean Ridge, opposite Prince Edward Island. The low profile of
    24-km-wide dominantly basaltic and trachybasaltic Marion Island is formed
    by two young shield volcanoes that rise above a flat-topped submarine
    platform. The 1,230-m-high island is dotted by about 150 cinder cones,
    smaller scoria cones, and coastal tuff cones. More than 130 scoria cones
    and many lava flows formed during the Holocene. Many of these appear
    younger than the 4,020 BP peat overlying one of the flows (Verwoerd, 1981).
    Young unvegetated lava flows appear to be only a few hundred years old
    (Verwoerd, 1967). The first historical eruption, during 1980, produced
    explosive activity and lava flows from a 5-km-long fissure that extended
    from the summit to the W coast.

    Information Contacts: Ian Meiklejohn and David Hedding, University of
    Pretoria, 0002, Pretoria, South Africa, 012-420 4049;(Email:
    ian.meiklejohn@up.ac.za, URL: www.up.ac.za/).
    __________________________________________________________
    Global Volcanism Program, NHB E-421 Tel: (202) 633-1800
    Smithsonian Institution Fax: (202) 357-2476
    Washington, DC 20560-0119 Email: gvp@si.edu

    Internet: www.volcano.si.edu/
  • Re: GVN Bulletin

    Sun, May 15, 2005 - 11:45 PM
    *****************************************************
    Bulletin of the Global Volcanism Network, March 2005
    *****************************************************
    From: Ed Venzke <venzke@volcano.si.edu>


    Bulletin of the Global Volcanism Network
    Volume 30, Number 3, March 2005

    Jun Jaegyu (Antarctica) Newly described submarine volcano near the tip of
    the Antarctic Peninsula
    Colima (Mexico) Lava flows up to 2.4 km long; March 2005 explosions;
    collapse on summit
    Soufriere St. Vincent (St. Vincent) Anomalous winds spread sulfurous odors,
    causing unwarranted fears
    Soufriere Hills (Montserrat) Comparative quiet during 26 November 2004 to 4
    March 2005
    Kliuchevskoi (Kamchatka Peninsula) Strombolian eruptions and lava flows
    during January-March 2005
    Bezymianny (Kamchatka Peninsula) Explosive eruption on 11 January 2005
    inferred from seismic data
    Canlaon (Philippines) Frequent ash emissions in March and April 2005;
    access remains restricted
    Ibu (Indonesia) Periodic ash emissions during June-August 2004 and inferred
    dome growth
    Kavachi (Solomon Islands) Eruption on 15 March 2004 breaks the water surface
    Lopevi (Vanuatu) Several lines of data confirm ongoing eruptions at this
    frequently erupting volcano
    OBITUARY Helicopter crash in the Philippines kills four PHIVOLCS staff and
    former director

    Editors: Rick Wunderman, Edward Venzke, and Gari Mayberry
    Volunteer Staff: Catherine Galley, Robert Andrews, Susan Nasr, William
    Henoch, Clement Prior, and Jacquelyn Gluck


    Jun Jaegyu
    Antarctic Sound, Antarctica
    63.48°S, 56.43°W; summit elev. -275 m (submarine)

    Jun Jaegyu is a young volcano near the Antarctic Peninsula visited in May
    2004 by researchers from a group of United States and Canadian universities
    aboard the U.S. National Science Foundation research vessel Laurence M.
    Gould (Cruise LMG04-04). The expedition's chief scientist was Eugene Domack
    of Hamilton College.

    Prior to this cruise, bathymetric swath maps from 2002 revealed a
    symmetrical volcano that had not been scoured by the advance and retreat of
    glaciers. The 2004 cruise dredged the volcano and found material that
    included fresh basalt in a flank area devoid of colonizing bottom-dwelling
    organisms. In contrast, observations suggested that other portions of the
    volcano were heavily colonized by bottom-dwelling organisms. The discovery
    of the volcano corroborated mariners' reports of discolored water in the
    area. These observations, and a thermal anomaly, were all consistent with
    comparatively recent volcanic activity.

    The volcano is located on the Antarctic continental shelf in the southern
    Antarctic Sound, ~9 km N of the easternmost point of Andersson Island and
    NW of Rosamel Island (figure 1), N of the mapped boundary of Late Cenozoic
    volcanic rocks. Swath bathymetric mapping indicated that the volcano stands
    ~700 m above the seafloor (at a depth of ~1,000 m) and thus extends to
    within ~275 m of the ocean surface. The seamount has an elongate,
    symmetrical shape and contains ~1.5 km^3 of volcanic rock.

    Figure 1. Jun Jaegyu submarine volcano (J) lies E of the extreme tip of the
    Antarctic Peninsula (see inset map) in the Antarctic sound, an area
    sheltered by several islands. Paulet Island, another volcano of probable
    Holocene age, lies just outside the Antarctic Sound on the SE side of
    Dundee Island. A better known Holocene volcano, Deception Island, lies to
    the NW (adjacent to the South Shetland Islands) as indicated by the arrow.
    Base map copied from Northern Graham Land and South Shetland Island,
    British Antarctic Territory Geologic Map (1:500,000) from BAS 500 G, sheet
    2, edition 1, 1978. Note that map coordinates shown are in degrees and
    minutes (eg. 57 00', 57 degrees and 0 minutes).

    Two observed positive thermal anomalies (up to 0.052ºC), recorded by
    temperature probes towed over the volcano from S to N, may be associated
    with two active volcanic centers. The more complex N temperature anomaly
    may also be associated with what appeared to be fresher lava flows.

    The volcano lies along a NW-SE oriented fault scarp. Material dredged from
    the volcano have not been dated because accurately dating vesicular,
    partially altered, young submarine basalts is problematic at best. No gas
    samples were collected during this cruise.

    Ashley Hatfield, a participant in the cruise and an undergraduate geology
    student at Hamilton College, advised by David Bailey and Eugene Domack,
    analyzed representative samples for whole-rock major and trace elements
    using XRF (X-ray fluorescence spectroscopy) and ICP-MS (inductively coupled
    plasma mass spectrometry). The samples are generally angular, glassy, and
    vesicular, having plagioclase, olivine, and clinopyroxene present as
    phenocryst phases, and with small rounded xenoliths being common (Hatfield
    and others, 2004). The samples were classified as alkali basalts and
    trachybasalts, and their chemical signatures were consistent with other
    known volcanoes throughout the northern Antarctic Peninsula.

    Hatfield noted that the volcano is named in honor of Jun Jaegyu, a young
    Korean scientist who lost his life during the 2003 field season in the
    South Shetland islands. He was participating in the Korean Antarctic
    Program through their geophysical observatory based in the South Shetland
    Islands (King Sejong Station, established in 1988 on the Barton Peninsula,
    King George Island at 62°13.4818' S, 58°47.4744' W).

    The scientific crew for this cruise included Hatfield, Bailey, and Domack,
    (Department of Geology, Hamilton College, Clinton, New York); Stefanie
    Brachfield, (Department of Earth and Environmental Sciences, Montclair
    State University, Upper Montclair, New Jersey); Robert Gilbert (Department
    of Geological Sciences, Queen's University, Kingston, Ontario); Scott
    Ishman (Department of Geology, Southern Illinois University, Carbondale,
    Illinois); Gerd Krahmann (Lamont-Doherty Earth Observatory of Columbia
    University, Palisades, New York); and Amy Leventer (Department of Geology,
    Colgate University, Hamilton, New York).

    Background. A morphologically youthful submarine volcanic center was
    discovered in the Antarctic Sound off the tip of the Antarctic Peninsula
    during oceanographic cruises in 2002 and 2004. Jun Jaegyu volcano rises to
    within 275 m of sea surface. It is the northernmost volcanic feature of the
    James Ross Island volcanic group, and lies ~32 km WNW of Paulet Island, a
    small volcano of probable Holocene age. The flanks of the newly documented
    volcano display fresh volcanic rocks devoid of marine organisms that
    blanket most of the edifice. Dredged samples included alkali basalts and
    trachybasaltic rocks. Mild positive thermal anomalies were detected over
    two possible submarine centers, and mariners' reports had noted discolored
    water in this area.

    Reference: Hatfield, A., Bailey, D., Domack, E., Brachfeld, S., Gilbert,
    R., Ishman, S., Krahmann, G., and Leventer, A., 2004, Jun Jaegyu volcano; A
    recently discovered alkali basalt volcano in Antarctic Sound, Antarctica:
    Eos, Transactions, American Geophysical Union, 85(47), Fall Meeting
    Supplement, Abstract T11A-1248.

    Information Contacts: David G. Bailey, Eugene Domack, and Ashley K.
    Hatfield, Department of Geosciences, Hamilton College, 198 College Hill
    Rd., Clinton, NY 13323, USA (Email: dbailey@hamilton.edu,
    edomack@hamilton.edu, and ahatfield@hamilton.edu).


    Colima
    Mexico
    19.514°N, 103.62°W; summit elev. 3,850 m
    All times are local (= UTC + 6 hours)

    The recent extrusion of block-lava that began on 30 September 2004
    continued through November 2004. Lava flows formed on the N and WNW flanks,
    with the respective dimensions ~2,400 m long by ~300 m wide, and ~600 m
    long by ~200 m wide. The total volume of erupted material, including lava
    and pyroclastic flows, was about 8.3 x 10^6 m^3 (Bulletin v. 30, no. 1).
    The termination of lava effusion was followed by intermittent explosive
    activity represented mainly by small gas-and-ash Vulcanian explosions.
    Their number gradually decreased during December 2004-March 2005 (figure 2).

    Figure 2. Eruptive activity of at Colima during September 2004-March 2005.
    The variations in the number of earthquakes produced by rockfalls and
    pyroclastic flows (heavy line) and by explosions and exhalations (dashed
    line) are shown. Double arrows show the beginning (B) and the end (E) of
    lava extrusion; three single arrows indicate the explosions of 10, 13, and
    26 March. Courtesy of Colima Volcano Observatory.
    Three relatively large explosions occurred in March (on the 10th, the 13th,
    and the 26th). Those of 10 and 13 March formed eruptive columns with
    heights of ~5 km above the crater and were accompanied by pyroclastic flows
    down the S flank. The lengths of associated pyroclastic flows did not
    exceed 2.8 km. The largest explosion to take place on 13 March generated
    fallout that included lapilli with a diameter of up to 2 cm. Ash fell at a
    distance of 12.5 km to the NE of the volcano (in the village of Los Mazos,
    Jalisco).

    Scientists made E-W topographic profiles on 12 October 2004 and 18 March
    2005 (figure 3). The profiles crossed an area on the summit's S flank. They
    disclosed that during this intervening interval there had been a collapse
    over an area of ~2,500 m^2.

    Figure 3. Two topographic profiles across the summit of Colima from the S
    flank made on 12 October 2004 and 18 March 2005. Courtesy of Colima Volcano
    Observatory.

    Background. The Colima volcanic complex is the most prominent volcanic
    center of the western Mexican Volcanic Belt. It consists of two
    southward-younging volcanoes, Nevado de Colima (the 4,320 m high point of
    the complex) to the N and the 3,850-m-high historically active Volcan de
    Colima to the S. A group of cinder cones of probable late-Pleistocene age
    is located on the floor of the Colima graben W and E of the Colima complex.
    Volcan de Colima (also known as Volcan Fuego) is a youthful stratovolcano
    constructed within a 5-km-wide caldera, breached to the S, that has been
    the source of large debris avalanches. Major slope failures have occurred
    repeatedly from both the Nevado and Colima cones, and have produced a thick
    apron of debris-avalanche deposits on three sides of the complex. Frequent
    historical eruptions date back to the 16th century. Occasional major
    explosive eruptions (most recently in 1913) have destroyed the summit and
    left a deep, steep-sided crater that was slowly refilled and then
    overtopped by lava dome growth.

    Information Contacts: Observatorio Vulcanologico de la Universidad de
    Colima, Colima, Col., 28045, Mexico (Email: ovc@cgic.ucol.mx; URL:
    www.ucol.mx/volcan/).


    Soufriere St. Vincent
    St. Vincent, West Indies
    13.33°N, 61.18°W; summit elev. 1,220 m
    All times are local (= UTC - 4 hours)

    Widespread sulfurous odors and haze during mid-February 2005 on the island
    of St. Vincent and as far as the Grenadines (50-75 km S) led some people to
    conclude that the smells reflected increased output of volcanic gases from
    the Soufriere volcano, St. Vincent, a possible harbinger of an eruption.
    Sulfurous odors are common on the volcano's W flank, but less frequent on
    other parts of the island.
    Scientists determined that typical winds diminish the sulfurous odors over
    much of the island, and the onset of the odors resulted from changes in
    wind patterns rather than increased gas output or other demonstrable changes.

    The Seismic Research Unit (SRU) collaborates with a small local unit called
    the Soufriere Monitoring Unit (which operates from the Ministry of
    Agriculture in Kingstown). The following report on the subject comes from
    SRU's Richard Robertson.

    "During the night of 16 February and most of the day of 17 February there
    were widespread reports of sulfurous smells throughout southern St. Vincent
    and as far as the Grenadines. The day of the 17th was hazy; people put
    these two things together and came up with the conclusion that the volcano
    was acting up. The sulfur smell is unusual since the wind direction is such
    that most of the smell from the fumaroles at the summit of the volcano gets
    blown out to sea and is usually only smelt by a few residents on the
    eastern flank of the volcano.

    "[SRU] . . . worked with Ms. Aisha Samuels, the head of the local volcano
    monitoring unit, to first investigate the report and later to quell fears
    that the volcano was doing anything unusual. We determined very early on
    that nothing serious was happening, since we have seismic stations both on
    the volcano and throughout the island [figure 4], none of which had
    recorded any increased seismicity. Further, we had just completed a GPS
    campaign on the island during January 2005, which revealed nothing unusual.
    It also involved two days of measurements on the summit of the volcano
    during which scientists were in very close proximity to the vent from which
    future eruptions will [likely] originate.

    Figure 4. A sketch map showing the island of St. Vincent, including
    Soufriere volcano, other volcanic centers, geographic features, and Seismic
    Research Unit monitoring instrumentation (as of February 2004). January
    2005 discussion of the instrumentation noted that it then included five
    seismic stations, eight GPS stations, and several dry-tilt sites. Courtesy
    of SRU.

    "We quickly determined that the reported 'activity' was due to an unusual
    southerly wind combined with the phenomena of Sahara dust which is common
    around this time of the year in St. Vincent and which results in very hazy
    conditions. However, to completely rule out the possibility of anything
    unusual happening in the crater that may not have been possibly detected by
    our various measurements, we advised the local Unit that they should visit
    the crater summit the next day (18 February)."

    That visit found nothing out of the ordinary. Accordingly, SRU did not
    think it necessary to update their website since it was so
    insignificant-"'a 10 day wonder' as they say in the West Indies, or a
    'pseudo-crisis.'" Such reports are common for St. Vincent and the entire
    region.

    Background. Soufriere St. Vincent is the northernmost and youngest volcano
    on St. Vincent island. The 1.6-km wide summit crater, whose NE rim is cut
    by a crater formed in 1812, lies on the SW margin of the 2.2-km-wide Somma
    crater, which is breached widely to the SW as a result of slope failure.
    The first historical eruption of the volcano took place during 1718; it and
    the 1812 eruption produced major explosions. Much of the N end of the
    island was devastated by a major eruption in 1902 that coincided with the
    catastrophic Mont Pelee eruption on Martinique. A lava dome was emplaced in
    the summit crater in 1971 during a strictly effusive eruption, forming an
    island in a lake that filled the crater prior to an eruption in 1979. The
    lake was then largely ejected during a series of explosive eruptions, and
    the dome was replaced with another.

    Information Contacts: Richard Robertson, Seismic Research Unit, The
    University of the West Indies, St. Augustine, Trinidad (URL:
    www.uwiseismic.com/); Aisha Samuel, Soufriere Monitoring Unit,
    Ministry of Agriculture, St. Vincent.


    Soufriere Hills
    Montserrat, West Indies
    16.72°N, 62.18°W; summit elev. 915 m
    All times are local (= UTC - 4 hours)

    This report covers the period 26 November 2004 to 4 March 2005. Soufriere
    Hills volcano remained quiet after late November, with seismic signals, gas
    emissions, and rockfalls all decreasing (table 1 and Bulletin v. 29 no. 10).

    Table 1. Geophysical and geochemical data recorded at Soufriere Hills, 26
    November 2004 to 4 March 2005. Wind directions or trouble with
    gas-monitoring equipment prevented measurement of SO2 fluxes on some days.
    Courtesy of MVO.

    Date Seismicity Hybrid Mixed VT LP SO2
    flux Rockfalls
    (2004-2005) level EQ's EQ's EQ's EQ's (metric
    tons/day)

    26 Nov-03
    Dec -- 9 -- 7 -- 130-590 4
    03 Dec-10
    Dec -- 7 -- -- -- 250-370 1
    10 Dec-17
    Dec -- 6 -- 7 -- 290-450 --
    17 Dec-24
    Dec -- 6 -- 1 -- 200-500 --
    24 Dec-31
    Dec -- 6 -- 2 1 300-550 --
    31 Dec-07
    Jan -- 4 -- -- -- 310-400 --
    07 Jan-14
    Jan -- 5 -- 5 -- 180-511 --
    14 Jan-21
    Jan -- 2 -- -- -- 300-3801 2
    21 Jan-28
    Jan -- 5 -- -- 1 350-6701 --
    28 Jan-04
    Feb -- 2 -- 1 7 4101 --
    04 Feb-11
    Feb low -- -- -- -- -- --
    11 Feb-18
    Feb low -- -- -- -- -- --
    18 Feb-25
    Feb low -- -- -- -- 280-9801 --
    25 Feb-04
    Mar low 6 -- 3 -- 6721 2

    While volcanic-tectonic and hybrid earthquakes (as many as 40/week) shook
    SHV from mid-October to late November, few were recorded between late
    November and early March (table 1). During the week of 25 February, winds
    shifted and carried the smell of sulfur to northern parts of the island.
    However, SO2 emissions remained low and stable throughout December,
    January, and February. The average for this reporting period was ~400
    tons/day, which is below the long-term average of 500 tons/day.

    Rain and mudflows have also subsided. A mudflow in the Belham Valley on 15
    December was the only event recorded for this reporting period.

    An exceptionally clear day enabled scientists to obtain unusually clear
    photos on 1 February 2005 (figures 5, 6, and 7). Flights were made during
    November, December, and January as well. During the November-February
    interval, scientists saw relatively few changes in the surface morphology.
    Chances Pond, the pool of brownish water sitting in the explosion pit
    formed on 3 March 2004, still remained. MVO scientists noted around 26
    November 2004 that the pond had changed from brownish to milky.

    Figure 5. Montserrat from the NNE at an altitude of ~ 1,500 m, clearly
    showing the island's three main volcanic centers: the oldest and extinct
    Silver Hills (more than a million years old) in the foreground; the
    highest, densely foliated Centre Hills (also extinct, 0.5-1 million years
    old), and the steaming Soufriere Hills (220,000 years old), furthest away.
    Courtesy of MVO.

    Figure 6. A photo of Soufriere Hills volcano taken from the NE showing the
    dome within the breached summit crater, and the SW-flank morphology. Much
    of the steam discharging was attributed to fumaroles. Photographed on 1
    February 2005. Courtesy of MVO.

    Figure 7. Recent deposits on the SW flank of Soufriere Hills as viewed from
    the NE on 1 February 2005. Prominent deltas appear at the mouths of the
    drainages shown, particularly at the mouth of the Tar River Valley.
    Courtesy of MVO.

    On 3 March 2005, scientists took a Fourier Transform Infrared spectrometer
    (FTIR) reading of the gas escaping from the crater vent at the summit
    (figure 6). The gas plume contained a ratio of hydrogen chloride to sulfur
    dioxide by mass of 0.35. This ratio showed no change since February.

    In September 2004, the Scientific Advisory Committee on Montserrat Volcanic
    Activity (SAC) joined MVO staff at the Montserrat Volcano Observatory to
    discuss recent activity (SAC, 2004). "Few signs of surface activity" was
    their appraisal of the period since March 2004. There had been little gas
    venting, ash venting, or tremor in six months, and no lava extrusion in 15
    months. This pause in activity, the SAC predicted, will last ~26 months,
    but could last as long as 170 months. SAC estimated risks for a variety of
    circumstances.

    Readers can access full reports issued by the SAC at the MVO website. The
    main report summarizes conclusions drawn from the meeting, while the
    technical report includes long-term monitoring data and risk assessments.

    Background. The complex andesitic Soufriere Hills volcano occupies the
    southern half of the island of Montserrat. The summit area consists
    primarily of a series of lava domes emplaced along an ESE-trending zone.
    Prior to 1995, the youngest dome was Castle Peak, which was located in
    English's Crater, a 1-km-wide crater breached widely to the E.
    Block-and-ash flow and surge deposits associated with dome growth
    predominate in flank deposits. Non-eruptive seismic swarms occurred at
    30-year intervals in the 20th century, but with the exception of a
    17th-century eruption, no historical eruptions were recorded on Montserrat
    until 1995. Long-term small-to-moderate ash eruptions beginning in that
    year were later accompanied by lava dome growth and pyroclastic flows that
    forced evacuation of the southern half of the island and ultimately
    destroyed the capital city of Plymouth, causing major social and economic
    disruption to the island.

    Reference: Scientific Advisory Committee on Montserrat Volcanic Activity
    (SAC), 2004, Assessment of the hazards and risks associted with the
    Soufriere Hills volcano, Montserrat: Second Report of the Scientific
    Advisory Committee on Montserrat Volcanic Activity, parts I (Main Report,
    24 p.) and II (Technical Report, 26 p.).

    Information Contacts: Montserrat Volcano Observatory (MVO), Fleming,
    Montserrat, West Indies (URL: www.mvo.ms/).


    Kliuchevskoi
    Kamchatka Peninsula
    56.057°N, 160.638°E; summit elev. 4,835 m
    All times are local (= UTC + 12 hours)

    From April to November 2004, the hazard status (Concern Color Code)
    remained at Yellow, with seismicity at background levels throughout this
    time, and occasional fumarole activity. Around 26 November 2004, the status
    was reduced from Yellow to Green, the lowest level. During November 2004,
    seismicity remained at background levels. Gas-and-steam plumes were seen up
    to 5 km altitude on 24 November 2004 and weak fumarolic activity was
    observed on several days. Kliuchevskoi was last reported on in April 2004
    (Bulletin v. 29, no. 4) and this report covers the interval through 31
    March 2005.

    On 14 January 2005 the Kamchatkan Volcanic Eruption Response Team (KVERT)
    raised the status at Kliuchevskoi from Green to Yellow as seismic activity
    at the volcano increased. On 12 January, around 21 shallow earthquakes of M
    1.0-1.7 and weak volcanic tremor were recorded. According to visual
    observations, weak gas-and-steam plumes were noted during 6-8 and 12
    January. The plumes extended E from the volcano on 7 January and SW for 5
    km on 12 January.

    On 16 January 2005 KVERT raised the status again, from Yellow to Orange, as
    seismic activity increased significantly. During 13-14 January, 15 shallow
    earthquakes of over M 1.25 were recorded, along with an increase in the
    amplitude of volcanic tremor. Visual observations on 14 January noted a
    weak gas-and-steam plume that extended N from the volcano. Satellite data
    showed a bright thermal anomaly over the summit on 15 January.

    During the third week of January, the total number of shallow earthquakes
    continued to increase. Gas-and-steam plumes rose to ~800 m above the lava
    dome. Incandescence was visible in the volcano's crater on several nights.

    Strombolian eruptions occurred during 20-23 and 27 January. Explosions sent
    volcanic bombs 50-300 m above the crater on several nights. Gas-and-steam
    plumes rose to a maximum height of 1.5 km above the crater. On 21 January a
    gas-and-steam plume with small amounts of ash extended as far as 23 km NE
    of the volcano. Throughout January seismicity was above background, with a
    large number of shallow earthquakes recorded daily. Gas-and-steam plumes
    that rose to ~1 km above the volcano's crater drifted SW on 29 January and
    NW on 31 January. A small amount of ash fell in the town of Klyuchi, about
    25 km to the NE, on 31 January.

    On 1 February around 1000, a mudflow carrying large blocks and trees
    traveled ~6 km down Kliuchevskoi's NW flank into the Kruten'kaya River. The
    mudflow reached a height of a few meters and trees were covered with mud to
    ~1.5 m. On 6, 8, and 9 February, ash plumes rose ~2.5 km above the
    volcano's crater. Gas-and-steam plumes rose to ~3 km during 6-9 February. A
    cinder cone was noted in the volcano's crater on 6 February. Fresh ash
    deposits were seen on the SW flank of Ushkovsky volcano (NW of
    Kliuchevskoi) on 7 February, and in Klyuchi on 9 February.

    Throughout the first week of February there were Strombolian eruptions in
    the terminal crater of Kliuchevskoi, and a lava flow traveled into
    Krestovsky channel on the volcano's NW flank. Phreatic bursts occurred in
    this channel when the lava contacted glaciers during 6-9 February and 12-13
    February. Ash plumes rose ~3 km above the volcano's crater during 12-14
    February. During 12-16 February, volcanic bombs were hurled 300-500 m above
    the crater, Strombolian eruptions occurred in the crater, and lava again
    traveled into the Krestovsky channel. On 16 February, a mudflow extended 27
    km. According to a news report, a lava flow from Kliuchevskoi melted a
    large section of Ehrman glacier on 21 February 2005.

    Moderate seismic and volcanic activity continued at Kliuchevskoi during 24
    February to 4 March. On 24 February lava continued to travel down the
    Krestovsky channel. Strombolian activity during this time sent plumes to ~1
    km above the volcano. Ash fell in the village of Icha, about 275 km to the
    SW on 26 February, and in Kozyrevsk, about 25 km to the W, on 1 March. Ash
    plumes were visible on satellite imagery on several days. During the first
    two weeks of March 2005, eruptions continued. Strombolian explosions
    occurred intermittently from a cinder cone in the summit crater. Lava flows
    extend from this cone down the NW flank. Occasional vigorous explosions
    from the summit crater and along the path of the lava flow produced ash
    plumes as high as 7-8 km and traveled many tens or hundreds of kilometers
    downwind. Ash-and-gas plumes rose up to 3.2 km above the crater on 10-16
    March and extended up to 150 km in various directions. Ash fell at
    Kozyrevsk on 11 March. Strombolian bursts rose about 500-1,000 m above the
    summit crater. Two lava flows were observed on the volcano's NW slope on 15
    March. Clouds obscured the volcano at other times. According to satellite
    data, a large thermal anomaly was registered at the volcano during the
    second week of March.

    During 11-18 March, Strombolian explosions occurred intermittently from a
    cinder cone in the summit crater. Lava flows extended from this cinder cone
    down the NW flank. Occasional vigorous explosions from the summit crater
    and along the path of the lava flow produced ash plumes that reached as
    high as 7-8 km altitude and drifted many tens or hundreds of kilometers
    downwind. Seismicity was above background at this time. On 11-12 March
    ash-and-gas plumes rose to 3.2 km above the crater. Ash fell in the town of
    Kozyrevsk, 30 km to the W, on 11 March. Strombolian bursts rose 500-1,000 m
    above the summit crater. On 15 March two lava flows were observed on the NW
    slope. The amplitude of volcanic tremor was about 12-13 x 10^-6 m/s on
    18-21 March and increased to about 46.0 x 10^-6 m/s on 22 March. From 1730
    till 1900 on 23 March it was up to 62 x 10^-6 m/s.

    On 24 March KVERT raised the hazard status to Red (the highest level) due
    to increased seismic and volcanic activity. A gas-and-steam plume
    containing ash rose to ~7.5 km altitude on 22 March and ~8.5 km altitude on
    23 March, extending NW. Ash fell in the town of Klyuchi during 23-24 March.
    According to data from AMC (Airport Meteorological Center) at Yelizovo, 340
    km S, an ash plume that rose to ~7 km altitude and extended 70-80 km to the
    NW was observed by pilots on 23 March. The amplitude of volcanic tremor
    decreased from 62 x 10^-6 m/s on 23 March to 26-22 x 10^-6 m/s on 25-26
    March. Satellite data indicated a 2- to 6-pixel (through the clouds)
    thermal anomaly over the volcano throughout the last week of March.
    Ash-and-gas plumes extended from the volcano 35 km N and 80 km W on 25
    March. Seismometers detected a great number of shallow earthquakes and 27
    earthquakes of Ml = 1.5-2.1.

    During about 27-28 March seismic activity at Kliuchevskoi decreased,
    leading KVERT to reduce the status to Orange. According to visual and video
    data during 27-28 March, a gas-and-steam plume containing some ash rose
    ~200 m above the crater and extended W. Ash-and-gas plumes rose to
    2,500-3,000 m above the crater and extended SE on 28 March, and NE on 29
    March. Incandescence above the summit crater was observed on 28 March.
    According to the data from the AMC at Yelizovo, an ash-and-gas plume rising
    about 2,000 m above the crater at 1420 on 31 March was observed by pilots.
    Ash-and-gas plumes extended 250 km SE on 28 March, 270 km NE on 29 March,
    and 100 km NW on 31 March.

    Background. Kliuchevskoi is Kamchatka's highest and most active volcano.
    Since its origin about 6,000 years ago, the beautifully symmetrical,
    4,835-m-high basaltic stratovolcano has produced frequent moderate-volume
    explosive and effusive eruptions without major periods of inactivity.
    Kliuchevskoi rises above a saddle NE of sharp-peaked Kamen volcano and lies
    SE of the broad Ushkovsky massif. More than 100 flank eruptions have
    occurred at Kliuchevskoi during the past roughly 3,000 years, with most
    lateral craters and cones occurring along radial fissures between the
    unconfined NE-to-SE flanks of the conical volcano between 500 m and 3,600 m
    elevation. The morphology of its 700-m-wide summit crater has been
    frequently modified by historical eruptions, which have been recorded since
    the late-17th century. Historical eruptions have originated primarily from
    the summit crater, but have also included numerous major explosive and
    effusive eruptions from flank craters.

    Information Contacts: Olga Girina, Kamchatka Volcanic Eruptions Response
    Team (KVERT), a cooperative program of the Institute of Volcanic Geology
    and Geochemistry, Far East Division, Russian Academy of Sciences, Piip Ave.
    9, Petropavlovsk-Kamchatskii 683006, Russia (Email: girina@kcs.iks.ru), the
    Kamchatka Experimental and Methodical Seismological Department (KEMSD), GS
    RAS (Russia), and the Alaska Volcano Observatory (USA); Alaska Volcano
    Observatory (AVO), cooperative program of the U.S. Geological Survey, 4200
    University Drive, Anchorage, AK 99508-4667, USA (URL:
    www.avo.alaska.edu/; Email: tlmurray@ usgs.gov), the Geophysical
    Institute, University of Alaska, P.O. Box 757320, Fairbanks, AK 99775-7320,
    USA (Email: eisch@dino.gi.alaska.edu), and the Alaska Division of
    Geological and Geophysical Surveys, 794 University Ave., Suite 200,
    Fairbanks, AK 99709, USA (Email: cnye@giseis.alaska.edu).


    Bezymianny
    Kamchatka Peninsula
    55.978°N, 160.587°E; summit elev. 2,882 m
    All times are local (= UTC + 12 hours)

    Bezymianny was reported on in Bulletin v. 29, no. 5, covering the June 2004
    eruption that was characterized by viscous lava flows and large ash plumes.
    This report covers the interval from July 2004 through February 2005. From
    July 2004 to December 2004, unrest and fumarolic activity were virtually
    continuous. The Concern Code Color (hazard status) remained at Yellow
    throughout much of this time, and seismicity was at or below background
    levels. The lava dome of the volcano continued to grow, and satellite data
    frequently indicated a thermal anomaly over the dome. Gas-steam plumes were
    observed almost daily from Klyuchi about 50 km away, rising to 3-5 km
    altitude, and extending in various directions for 10-15 km.

    KVERT raised the hazard status from Yellow to Orange on 7 January as
    seismicity increased. On 11 January, KVERT raised the status from Orange to
    Red (the highest level). An explosive eruption, inferred from seismic data,
    began at 2002 on 11 January 2005 and was believed to have produced an ash
    column to 8-10 km altitude. No visual or satellite data were available as
    dense clouds obscured the volcano. Seismic activity was above background
    levels during the first week of January and increased continuously. About
    60 earthquakes of magnitude 1.25-2.25, and numerous weaker, shallow events
    registered during 7-11 January. Intermittent volcanic tremor was recorded
    on 10 January.

    The hazard status was lowered from Red to Orange on 12 January when seismic
    activity returned to background levels following the eruption of 11
    January. Seismicity remained at background levels so the status was lowered
    from Orange to Yellow on 14 January.

    During February 2005 gas-steam plumes were observed frequently, rising
    50-1,000 m above the dome and drifting 10-15 km in various directions.
    Satellite data frequently indicated a thermal anomaly over the dome. The
    status remained at Yellow as of 29 April 2005.

    Background. Prior to its noted 1955-56 eruption, Bezymianny volcano had
    been considered extinct. The modern Bezymianny volcano, much smaller in
    size than its massive neighbors Kamen and Kliuchevskoi, was formed about
    4,700 years ago over a late-Pleistocene lava-dome complex and an ancestral
    volcano that was built between about 11,000-7,000 years ago. Three periods
    of intensified activity have occurred during the past 3,000 years. The
    latest period, which was preceded by a 1,000-year quiescence, began with
    the dramatic 1955-56 eruption. This eruption, similar to that of Mount St.
    Helens in 1980, produced a large horseshoe-shaped crater that was formed by
    collapse of the summit and an associated lateral blast. Subsequent episodic
    but ongoing lava-dome growth, accompanied by intermittent explosive
    activity and pyroclastic flows, has largely filled the 1956 crater.

    Information Contacts: Olga Girina, Kamchatka Volcanic Eruptions Response
    Team (KVERT), a cooperative program of the Institute of Volcanic Geology
    and Geochemistry, Far East Division, Russian Academy of Sciences, Piip Ave.
    9, Petropavlovsk-Kamchatskii 683006, Russia (Email: girina@kcs.iks.ru), the
    Kamchatka Experimental and Methodical Seismological Department (KEMSD), GS
    RAS (Russia), and the Alaska Volcano Observatory (USA); Alaska Volcano
    Observatory (AVO), a cooperative program of the U.S. Geological Survey,
    4200 University Drive, Anchorage, AK 99508-4667, USA (URL:
    www.avo.alaska.edu/; Email: tlmurray@ usgs.gov), the Geophysical
    Institute, University of Alaska, P.O. Box 757320, Fairbanks, AK 99775-7320,
    USA (Email: eisch@dino.gi.alaska.edu), and the Alaska Division of
    Geological and Geophysical Surveys, 794 University Ave., Suite 200,
    Fairbanks, AK 99709, USA (Email: cnye@giseis.alaska.edu).


    Canlaon
    central Philippines
    10.412°N, 123.132°E; summit elev. 2,435 m
    All times are local (= UTC + 8 hours)

    Ash emissions and sporadic seismicity at Canlaon between March 2003 and
    March 2004 were reported in Bulletin v. 29, no.12. A brief ash emission
    began at Canlaon around 0930 on 21 January 2005. The eruption cloud rose
    ~500 m above the active crater and drifted WNW and SW. No coincident
    volcanic earthquakes were recorded. Fine ash was deposited in the city of
    Cabagnaan, ~5.5 km SW of the crater. The Philippine Institute of
    Volcanology and Seismology (PHIVOLCS) advised the public to avoid entering
    the 4-km-radius Permanent Danger Zone around Canlaon.

    Ash emissions began again on 20 March around 1300. Small amounts of ash
    fell in the town of Guintubdan 5 km W of the volcano. During 24 March to 4
    April, sporadic ash emissions rose to a maximum of 1 km above the volcano.
    During this time ash fell in the towns of La Castellana (16 km SW of the
    crater), Upper Sag-ang, Yubo (5-6 km SW), and Guintubdan (5-6 km WNW). Due
    to this unrest, PHIVOLCS raised the Alert Level from 0 to 1 (on a scale of
    0-5) on 30 March. According to a news article, pilots were advised to avoid
    flying near Canlaon.

    On March 22 the Provincial Disaster Management Team (PDMT) warned it would
    apprehend trekkers and faith healers who ventured to Mount Canlaon during
    Holy Week. Trekking to Mount Canlaon has become a practice by some faith
    healers and mountaineers who believe that the volcano is a source of
    supernatural powers.

    On 31 March at 0601 and 1715, two mild ash ejections reached heights of
    about 200-300 m above the summit before drifting NW and SW. Ash was
    deposited at Guintubdan, Upper Sag-ang, and Upper Mansalanao. A low-energy
    ash emission on 7 April at 1429 generated a cloud which rose to a height of
    ~100 m above the crater and drifted SW. According to PHIVOLCS, the seismic
    monitoring network around the volcano did not record any earthquakes during
    this event. During 13-14 April, mild ash emissions produced plumes to a
    height of ~700 m above the crater. During 15-17 April, moderate-to-strong
    emissions produced ash plumes to ~2 km above the crater and deposited ash
    in villages as far as La Castellana. None of these ash emissions was
    associated with seismicity, indicating that the activity is likely
    hydrothermal in nature, and taking place at shallow levels in the crater.

    Throughout this period Canlaon remained at Alert Level 1. As of the end of
    April 2005, the 4-km-radius Permanent Danger Zone (PDZ) was restricted and
    all treks to the summit remained suspended.

    Background. Canlaon volcano (also spelled Kanlaon), the most active of the
    central Philippines, forms the highest point on the island of Negros. The
    massive 2,435-m-high stratovolcano is dotted with fissure-controlled
    pyroclastic cones and craters, many of which are filled by lakes. The
    summit of Canlaon contains a broad elongated northern caldera with a crater
    lake and a smaller, but higher, historically active crater to the S. The
    largest debris avalanche known in the Philippines traveled 33 km to the SW
    from Canlaon. Historical eruptions, recorded since 1866, have typically
    consisted of phreatic explosions of small-to-moderate size that produce
    minor ashfalls near the volcano.

    Information Contacts: Philippine Institute of Volcanology and Seismology
    (PHIVOLCS), Department of Science and Technology, PHIVOLCS Building, C.P.
    Garcia Avenue, Univ. of the Philippines Campus, Diliman, Quezon City,
    Philippines (URL: www.phivolcs.dost.gov.ph/); Chris Newhall, USGS,
    Box 351310, University of Washington, Seattle, WA 98195-1310, USA(Email:
    cnewhall@ess.washington.edu); Philippine Star (URL: www.philstar.com/).


    Ibu
    Halmahera, Indonesia
    1.48°N, 127.63°E; summit elev. 1,325 m

    The Directorate of Volcanology and Geological Hazard Mitigation (DVGHM)
    released ten nearly identical weekly reports on Ibu during 31 May-29 August
    2004. They noted that Ibu emitted "white ash" (steam plumes) reaching
    ~50-150 m above the crater rim. Continued growth of the intracrater lava
    dome was either recognized or assumed. Ibu lacked a working seismic
    instrument. Its hazard status remained at Level II (Yellow, a condition
    meaning 'caution or on guard' ('waspada' in Indonesian).

    Our last few reports discussed mild ash explosions in 1999 (Bulletin v. 24,
    no. 5), thermal alerts during 28 May-3 October 2001 and the fact that
    activity during much of 2002 was likely just below the detection threshold
    (Bulletin v. 28, no. 3).

    Background. The truncated summit of Gunung Ibu stratovolcano along the NW
    coast of Halmahera Island has large nested summit craters. The inner
    crater, 1 km wide and 400 m deep, contained several small crater lakes
    through much of historical time. The outer crater, 1.2 km wide, is breached
    on the N side, creating a steep-walled valley. A large parasitic cone is
    located ENE of the summit. A smaller one to the WSW has fed a lava flow
    down the western flank. A group of maars is located below the northern and
    western flanks of the volcano. Only a few eruptions have been recorded from
    Ibu in historical time, the first a small explosive eruption from the
    summit crater in 1911. An eruption producing a lava dome that eventually
    covered much of the floor of the inner summit crater began in December 1998.

    Information Contacts: Directorate of Volcanology and Geological Hazard
    Mitigation (DVGHM), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL:
    www.vsi.dpe.go.id/).


    Kavachi
    Solomon Islands
    9.02°S, 157.95°E; summit elev. -20 m (submarine)
    All times are local (= UTC + 11 hours)

    The Solomon Islands' goverment-supported web service, the People First
    Network (PFnet) reported in March 2004 that Corey Howell of The Wilderness
    Lodge, Gatokae Island, observed Kavachi erupting (figure 8). Kavachi is
    among the world's few regularly erupting submarine volcanoes that sends
    material above the ocean surface in witnessed (and reported) eruptions.

    Figure 8. A photo of Kavachi erupting as seen on 15 March 2004. The
    original caption on PFnet was "Kavachi awoke on Monday in spectacular
    fashion after an eight-month slumber . . .." Courtesy of Corey Howell.

    The figure caption on PFnet notes an 8-month period of Kavachi inactivity,
    which was also confirmed in brief correspondence with Howell. A report that
    summarized the interval between the summer of 2001 and the end of 2003
    (Bulletin v. 29, no. 1) lacked any mention of an eruption during mid-August
    2003, eight months before the recent eruption.

    Background. Kavachi, one of the most active submarine volcanoes in the SW
    Pacific, occupies an isolated position in the Solomon Islands far from
    major aircraft and shipping lanes. Kavachi, sometimes referred to as Rejo
    te Kvachi ("Kavachi's Oven"), is located S of Vangunu Island only about 30
    km N of the site of subduction of the Indo-Australian plate beneath the
    Pacific plate. The shallow submarine basaltic-to-andesitic volcano has
    produced ephemeral islands up to 1 km long many times since its first
    recorded eruption during 1939. Residents of the nearby islands of Vanguna
    and Nggatokae (Gatokae) reported "fire on the water" prior to 1939, a
    possible reference to earlier submarine eruptions. The roughly conical
    volcano rises from water depths of 1.1-1.2 km on the N and greater depths
    to the S. Frequent shallow submarine and occasional subaerial eruptions
    produce phreatomagmatic explosions that eject steam, ash, and incandescent
    bombs above the sea surface. On a number of occasions lava flows were
    observed on the surface of ephemeral islands.

    Information Contacts: Corey Howell, The Wilderness Lodge, P.O. Box 206,
    Homiara, Solomon Islands (Email: peava@thewildernesslodge.org; URL:
    www.thewildernesslodge.org/); People First Network (PFnet), Rural
    Development Volunteers Association, Ministry of Provincial Government and
    Rural Development, PO Box 919, Honiara, Solomon Islands (Email:
    pfnet@pipolfastaem.gov.sb; URL: www.peoplefirst.net.sb/).


    Lopevi
    Central Islands, Vanuatu
    16.507°S, 168.346°E; summit elev. 1,413 m
    All times are local (= UTC + 11 hours)

    Previously, Bulletin reports for 2003 chiefly discussed either
    aviation-related reports about ash plumes or satellite data, such as the
    spectroscopic sensing of SO2 or infrared data in the form of MODVOLC
    thermal alerts (Bulletin v. 27, no. 12; v. 28, nos. 1 and 6; v. 29, no. 6).
    Since those reports more first-hand observations of conditions on the
    ground have emerged regarding Lopevi during 2003. Numerous thermal
    anomalies were detected by the MODIS satellite at Lopevi during July 2003
    to March 2005 (table 2). Other observations also indicate activity
    continuing in 2005. Lopevi erupts nearly continuously, but, because it is
    an uninhabited island, activity often goes unreported.

    Table 2. MODVOLC thermal anomalies as observed from the MODIS satellite for
    Lopevi volcano for the period July 2003 to March 2005. The third column
    gives the MODIS sensor that detected the hot spot; T = Terra-MODIS, and
    A=Aqua MODIS. The fourth column shows radiance in watts per square meter,
    per steradian, per micron (W m-2 sr-1 mm-1) in MODIS band 21 (central
    wavelength of 3.959 mm). Courtesy of the Hawaiian Institute of Geophysics
    and Planetology.

    Date Time Sensor Spectral
    (mo/dy/ yr) (UTC) radiance

    02/16/2005 0245 A 2.813
    02/05/2005 1355 A 0.983
    02/05/2005 1355 A 1.426
    01/30/2005 1130 T 0.710
    01/03/2005 0220 A 2.560
    12/15/2004 1115 T 3.425
    11/18/2004 0210 A 2.771
    11/13/2004 1115 T 0.886
    10/04/2004 2300 T 3.009
    09/28/2004 1410 A 0.937
    09/28/2004 1410 A 1.052
    09/17/2004 1125 T 1.123
    09/10/2004 1115 T 1.186
    08/07/2004 1130 T 1.015
    07/19/2004 1400 A 0.362
    07/07/2004 2305 T 2.883
    05/28/2004 1125 T 1.797
    05/28/2004 1125 T 3.012
    05/12/2004 1425 A 1.353
    05/12/2004 1125 T 2.332
    04/22/2004 1150 T 0.930
    04/17/2004 1130 T 0.949
    03/27/2004 1415 A 2.314
    03/27/2004 1415 A 0.740
    03/02/2004 1120 T 1.636
    02/28/2004 1350 A 0.965
    02/28/2004 1350 A 1.017
    02/17/2004 1410 A 1.218
    02/01/2004 1405 A 0.917
    01/15/2004 0230 A 4.117
    11/02/2003 1125 T 1.154
    11/02/2003 1125 T 2.527
    10/08/2003 1130 T 2.212
    10/04/2003 0225 A 3.680
    09/02/2003 0225 A 3.815
    08/21/2003 1130 T 2.143
    08/18/2003 1400 A 0.917
    08/16/2003 1410 A 1.100

    Lopevi remains a danger for the region, and particularly for Paama Island,
    the closest inhabited island (6 km away). The explosive eruption of 2001
    turned day into night for several hours, and the ashfall polluted the
    islanders' water supply to the point where the Australian Navy had to send
    a ship to bring residents drinking water. Since then, wells equipped with
    hand-operated pumps have been installed on Paama's N side, the flank
    threatened most directly. Lardy suggested that evacuating 1,633 inhabitants
    (the number cited in a 1999 census) is not realistic, but that the
    population could be supplied with dust-filtering face masks prior to the
    next eruption. The majority of Paama Island residents live on the W coast
    and even for the closest residents on Paama's N coast, the view of Lopevi
    is often limited.

    Observations during 2003. Michel Lardy summarized the activity during 2003.
    The major volcanic events of June 2001 (Bulletin v. 26, no. 8) and of June
    2003 (Bulletin v. 28, no. 6) appear to have originated at the adventive
    crater and through fractures in the island's N and W sides (figures 9 and
    10). In particular, vents on the N, NW, and W opened in 2001 and 2003. Vent
    opening in 2001 occurred at 16° 31.879' S, 168° 19.846 E. A 2001 lava flow
    was prominent on the N flank. Radar interferometry depicted lava in 2001 on
    the volcano's N side, in the crater, and at several places on the N and W
    flanks.

    Figure 9. Lava flows down Lopevi's N flank and entering the sea during
    June(?) 2003. Note multiple lava flows, distinct vent areas, and the
    presence of at least two active points of entry into the ocean at the time
    of the photo. Photo credit, Shane Cronin (Massey University).

    Figure 10. A closer look at the vents feeding lava flows down Lopevi's N
    flank during June(?) 2003. The vents formed along radial fractures. Photo
    credit, Shane Cronin (Massey University).

    Observations during 2004. During September 2004 thermal anomalies were
    detected four times, as many times as any month during the interval shown
    on table 2. However, none of the 28 September anomalies were unusually
    strong (~1 W m^-2 sr^-1 mm^-1) and the spectral radiance of some other
    observations were several-fold larger (up to ~3.8 W m^-2 sr^-1 mm^-1).

    Volcano tour guide John Seach visited SE Ambrym volcano in November 2004.
    At that time he received reports from residents about previously unreported
    eruptions of Lopevi that occurred during 2004. Specifically, during
    September 2004, five large booming noises were heard coming from Lopevi by
    villagers in S Ambrym. Explosions were separated by 2 minutes. The next day
    there was ashfall on N and W Ambrym.

    Observations during 2005. According to Seach, local observers in Vanuatu
    indicated ongoing eruptive activity at Lopevi beginning at the end of
    January 2005 and continuing into February.The Wellington VAAC is the key
    group providing aviators with reports on Lopevi eruptions and ash plumes.
    Their website posted all Volcanic Activity Advisories during 90 days prior
    to 28 March, but there were no reports for Lopevi during that interval.
    This absence of reports could be for a variety of reasons, such as
    relatively few if any plumes during that interval. Other reasons might also
    include extensive weather clouds screening satellite and pilot
    observations, or an absence of reports from pilots or people in the field
    to pass observations to the VAAC.

    On 21 March 2005 IRD staff members observed Lopevi in usually clear weather
    conditions (figures 11 and 12). These two photos highlight Lopevi's summit
    crater and its off-axis NW-flank (adventive) crater. The adventive crater
    has been a feature of the edifice since the early 1960s (Bulletin v. 24,
    nos. 2 and 7; the latter issue contains a map showing the then-recent crater).

    Figure 11. Annotated, N-looking view of Lopevi showing summit crater and
    adventive crater, and two other islands in the background. Copyrighted
    photo taken 21 March 2005 by P. Bani, IRD.

    Figure 12. A photo of Lopevi's adventive NW-flank crater taken looking S
    from an altitude of ~ 1 km. White deposits occur along considerable
    portions of the larger crater's rim. The color version of this photo
    indicates a yellow region lies on the internal crater (the crater inside
    the larger crater and in the middle of the photo). Other areas of yellow
    color were also visible farther to the right, although in this shot it was
    masked by a hazy plume. The yellow color was attributed to sulfur deposits.
    Copyrighted photo taken 21 March 2005; provided courtesy of M. Lardy, IRD.

    The close-up photo (figure 12) shows a circular fracture along the crater's
    rim and circumferential fractures along its walls, probably the result of
    subsidence caused by the constant release of gas from the magma reservoir.
    White hydrothermal deposits were thought to have been associated with this
    gas release. The observers also saw yellow sulfur deposits near the
    internal crater and between it and the northern rim (to the right on the
    photo).

    The perpendicular fractures visible just outside the crater (bottom center
    on the photo) were also judged most likely related to this subsidence
    associated with gas release. The small inner crater was a zone of active
    deposition (building up that crater). This pattern, apparently cyclical,
    has been visible since 1998, when Lopevi resumed an active phase following
    a quiet period of about fifteen years during which only fumaroles were
    observed. The summit crater (1,367 m elevation, figure 12) appears little
    changed when compared with the same crater 1995 photos taken in 1995. The
    major volcanic events of June 2001 (Bulletin v. 26, no. 8) and of June 2003
    (Bulletin v. 28, no. 6) originated in the adventive crater and through
    fractures in the island's N and W sides.

    Lardy also commented that "observations made since the 19th century suggest
    an activity cycle of 15 to 20 years, yet it remains difficult to forecast
    the occurrence of major eruptive phases within the cycle. Although there
    appears to be a recurrence of events in the month of June, it would be rash
    to attempt to predict the next eruption given the current state of our
    knowledge. Since November 2004, a micro-barometer has been set up on Paama
    Island. It is connected to the SSI network (which monitors compliance with
    the international ban on nuclear explosions) and has been recording the
    explosive volcanic events occurring on Lopevi and Ambrym Islands. Real time
    measurements should complement this monitoring system."

    Reference: Le Pichon, A., and Drob, D., 2005, Probing high-altitude winds
    using infrasound from volcanoes: Jour. of Geophys. Res. (in press)

    Background. The small 7-km-wide conical island of Lopevi is one of
    Vanuatu's most active volcanoes. A small summit crater containing a cinder
    cone is breached to the NW and tops an older cone that is rimmed by the
    remnant of a larger crater. The basaltic-to-andesitic volcano has been
    active during historical time at both summit and flank vents, primarily
    along a NW-SE-trending fissure that cuts across the island, producing
    moderate explosive eruptions and lava flows that reached the coast.
    Historical eruptions at the 1,413-m-high volcano date back to the mid-19th
    century. The island was evacuated following eruptions in 1939 and 1960. The
    latter eruption, from a NW-flank fissure vent, produced a pyroclastic flow
    that swept to the sea and a lava flow that formed a new peninsula on the W
    coast.

    Information Contacts: Michel Lardy and Philipson Bani, Institut de
    Recherche pour le developpement (IRD), CRV, BP A 5 Noumea, New Caledonia
    (E.mail Michel.Lardy@noumea.ird.nc, Philpson.Bani@noumea.ird.nc); Morris
    Harrison, Department of Geology, Mines, and Water Resources, PMB 01,
    Port-Vila, Vanuatu (E.mail: observatoire@vanuatu.com.vu; URL:
    www.mpl.ird.fr/suds-en-li....htm#suds);
    Shane Cronin, Soil and Earth Sciences Group, Institute of Natural
    Resources, Massey University, Private Bag 11 222, Palmerston North, New
    Zealand (Email: S.J.Cronin@massey.ac.nz; John Seach, PO Box 16, Chatsworth
    Island, NSW 2469, Australia (Email: john@volcanolive.com,
    jseach@hotmail.com, URL: www.volcanolive.com/); Hawai'i Institute of
    Geophysics and Planetology, University of Hawaii and Manoa, 168 East-West
    Road, Post 602, Honolulu, HI 96822 (URL: modis.higp.hawaii.edu);
    Wellington Volcanic Ash Advisory Center (VAAC), MetService, PO Box 722,
    Wellington, New Zealand (URL: www.metservice.co.nz/).

    __________________________________________________________
    Global Volcanism Program, NHB E-421 Tel: (202) 633-1800
    Smithsonian Institution Fax: (202) 357-2476
    Washington, DC 20560-0119 Email: gvp@si.edu

    Internet: www.volcano.si.edu/
  • Re: GVN Bulletin

    Fri, June 10, 2005 - 11:14 PM
    *****************************************************
    Bulletin of the Global Volcanism Network, April 2005
    *****************************************************
    From: Ed Venzke <venzke@volcano.si.edu>


    Bulletin of the Global Volcanism Network
    Volume 30, Number 4, April 2005

    Lascar (Chile) 4 May 2005 eruption sends ash over 1,000 km SE, 3/4 of the
    way to Buenos Aires
    Fernandina (Galapagos Islands) Lava flows down S flank from circumferential
    vents near caldera rim
    Anatahan (Mariana Islands) Explosive eruption on 6 April 2005 issues
    highest ash plume recorded here
    Vailulu'u (Samoa) ALIA cruise discloses new cone in the summit crater
    Awu (Indonesia) Stable during mid- to late August 2004
    Karthala (Comoros) 16 April 2005 seismicity leading to eruption;
    near-source tephra 1.5 m thick
    Ol Doinyo Lengai (Tanzania) Tall hornito almost reaches summit elevation;
    more lava spills over rim

    Editors: Rick Wunderman, Edward Venzke, and Gari Mayberry
    Volunteer Staff: Robert Andrews, Catherine Galley, William Henoch, Clement
    Pryor, Steven Bentley, and Jerome Hudis


    Lascar
    northern Chile
    23.37°S, 67.73°W; summit elev. 5,592 m
    All times are local (= UTC - 3 hours)

    Lascar, the most active volcano in northern Chile, erupted on 4 May 2005.
    Although the eruption was substantial, thus far there is an absence of
    reports from anyone who saw the eruption at close range. Preliminary
    assessments came mainly from satellite sensors and distant affects
    witnessed in Argentina. This report is based on one sent to us by Chilean
    Observatorio Volcanologico de los Andes del Sur (OVDAS) scientists Jose
    Antonio Naranjo and Hugo Moreno, discussing events around 4 May, with brief
    comments on some of Lascar's behavior in the past several years, and
    suggestions for future monitoring.

    Lascar sits ~70 km SW of the intersection between Chile, Argentina, and
    Bolivia, ~300 km inland from the Chilean port city of Antofagasta. This
    part of the coast lies along the Atacama desert, and on flat terrain tens
    of kilometers W of Lascar resides a large salt pan, the Salar de Atacama
    (about 50 x 150 km). The settlement of Toconao is ~33 km NW of Lascar.
    Previous reports discussed field observations during 13 October 2002 to 15
    January 2003, and fine ash discharged from fumaroles on 9 December 2003
    (Bulletin v. 28, no. 3, and v. 29, no. 1).

    Naranjo and Moreno concluded that at roughly 0400 on 4 May an explosive
    eruption ejected an ash cloud to a tentative altitude on the order of 10 km
    that dispersed to the SE. About 2 hours later the cloud began dropping ash
    on Salta, Argentina. Satellite images portrayed the ash cloud's dispersal.
    An aviation 'red alert' was issued by the Buenos Aires Volcanic Ash Center;
    they saw the plume over Argentina at altitudes of 3-5 km.

    Shortly after atmospheric impacts of the 4 May eruption became apparent,
    the Buenos Aires VAAC notified OVDAS that NW Argentine cities had reported
    falling ash. These cities, all SE of Lascar, included Jujuy, Salta,
    Santiago del Estero, and Santa Fe-locations with respective approximate
    distances from Lascar of 260, 275, 580, and 1,130 km. The Argentine
    province of Chaco, along the country's NE margin, was also noted as
    receiving ash. Buenos Aires (~1,530 km SE of Lascar) remained ~400 km
    beyond the point of the farthest detected ashfall.

    Patricia Lobera, a professor in Talabre, Argentina, 17 km E of Lascar, said
    that eruption noises were not heard there on the morning of 4 May. When
    observers saw the plume from Talabre that morning they reportedly thought
    the plume looked similar to those on previous days.

    Remotely sensed hot spots were detected on a GOES satellite image for 0339
    (0639 UTC) on 4 May, showing the first evidence of an eruption. In a later
    image, at 0409, the thermal anomaly had increased, and the image suggested
    a growing, ash-bearing cloud then trending ~23 km to the SE. The thermal
    anomaly diminished in intensity by 0439, remaining diminished thereafter,
    but by that time the plume's leading margin extended over ~100 km SE and
    its tail had detached from the volcano. At 0509 the plume reached 170 km
    SE. According to a press report, at around 0600 ash fell in Salta (~275 km
    SE of Lascar).
    Rosa Marquilla, a geologist at the University of Salta, reported that
    residents there noticed a mist attributed to the eruption, which hung over
    the city until at least to 1600, after which, the sky gradually cleared.
    Preliminary description of the petrography of the ash that fell in Salta
    came from Ricardo Pereyra (University of Salta) who saw crystal fragments
    (pyroxenes, feldspars, and magnetite) and fragments of volcanic glass
    containing plagioclase mircrolites. Lithic fragments were not observed.

    The OVDAS authors concluded that, apparently since the year 2000, Lascar
    underwent constant degassing from an open vent within the ~780-m-diameter
    active central crater. Sporadic explosions as in July 2000 and October
    2002, and in this case, 4 May 2005, could be due to diverse causes. For
    example, there may have been temporarily obstructed conduits at depth,
    local collapses blocking the vent at the crater floor, or fresh magma
    injection contacting groundwater. Extrusion of a viscous dome lava also
    might explain the sudden explosions. That circumstance would presumably
    lead to visibly increased fumarolic output.

    Naranjo and Moreno had several suggestions for ongoing monitoring. First,
    they suggested developing closer long-term contacts, including people able
    to visually monitor the volcano directly, as well as continued systematic
    contact with the Buenos Aires VAAC and their satellite analysts. They
    recommended ongoing relations with the University of Hawaii (MODVOLC)
    program to remotely sense hot-spots. They went on to suggest a campaign of
    stereo aerial photography to detect changes in the active crater. They
    advocated notifying local inhabitants of the possibility of ash falls
    before another explosive episode. They pointed out that mountaineers should
    be made aware of elevated risks within 8 km of the active crater.

    Background. Lascar is the most active volcano of the northern Chilean
    Andes. The andesitic-to-dacitic stratovolcano contains six overlapping
    summit craters. Prominent lava flows descend its NW flanks. An older,
    higher stratovolcano 5 km to the E, Volcan Aguas Calientes, displays a
    well-developed summit crater and a probable Holocene lava flow near its
    summit (de Silva and Francis, 1991). Lascar consists of two major edifices;
    activity began at the eastern volcano and then shifted to the western cone.
    The largest eruption of Lascar took place about 26,500 years ago, and
    following the eruption of the Tumbres scoria flow about 9,000 years ago,
    activity shifted back to the eastern edifice, where three overlapping
    craters were formed. Frequent small-to-moderate explosive eruptions have
    been recorded from Lascar in historical time since the mid-19th century,
    along with periodic larger eruptions that produced ashfall hundreds of
    kilometers away from the volcano. The largest historical eruption of Lascar
    took place in 1993, producing pyroclastic flows to 8.5 km NW of the summit
    and ashfall in Buenos Aires.

    References: Gardeweg, M., 1989, Informe preliminar sobre la evolucion de la
    erupcion del volcan Lascar (II Region): noviembre 1989: Servicio Nacional
    de Geologia y Mineria, Informe Inedito (unpublished report), 27 p.

    Gardeweg, M., and Lindsay, J., 2004, Lascar Volcano, La Pacana Caldera, and
    El Tatio Geothermal Field: IAVCEI General Assembly Pucon 2004, Field Trip
    Guide-A2, 32 p.

    Gardeweg, M., Medina, E., Murillo, M., and Espinoza, A., 1993, La erupcion
    del 19-20 de abril de 1993: VI informe sobre el comportamiento del volcan
    Lascar (II Region): Servicio Nacional de Geologia y Mineria, Informe
    Inedito (unpublished report), 20 p.

    Information Contacts: Jose Antonio Naranjo and Hugo Moreno, Programa Riesgo
    Volcanico, Servicio Nacional de Geologia y Mineria, Avda. Santa Maria 0104,
    Casilla 1347, Santiago, Chile; Gustavo Alberto Flowers, Buenos Aires
    Volcanic Ash Advisory Center (Buenos Aires VAAC), Servicio Meteorologico
    Nacional-Fuerza Aerea Argentina, 25 de mayo 658, Buenos Aires, Argentina
    (URL: www.meteofa.mil.ar/vaac/vaac.htm).


    Fernandina
    Galapagos Islands, Ecuador
    0.37°S, 91.55°W; summit elev. 1,476 m
    All times are local (= UTC - 6 hours)

    On the morning of 13 May 2005, a new eruption started on uninhabited
    Fernandina volcano (figure 1). Fernandina last erupted in 1995 (figure 2),
    and had been quiet and seemingly unchanged when a team from the Ecuadorian
    Institute of Geophysics (IG) flew over it in late March 2005. On 11 May an
    M 5.0 earthquake occurred with an epicenter ~30 km E of Fernandina's
    center. Only two other earthquakes have been located by the U.S. Geological
    Survey (USGS) within 100 km of Fernandina in last 4.5 years (M 4.0 on 23
    February 2005 and M 4.6 on 16 April 2005), both having epicenters ~70-80 km
    SE of Fernandina's center. A seismic station, installed by the IG in 1996
    on the NE coast of the island, was out of service at the time of eruption.

    Figure 1. Sketch map of Fernandina, showing the conspicuous summit caldera,
    and indicating the flow fields and circumferential vent area from the 13
    May 2005 eruption (as mapped on 14 May by airborne reconnaissance
    and reported by the Charles Darwin Research Station). Key features
    include the active circumferential fissure vent and two main areas impacted
    by lava flows. The eastern area contained lava flows still mobile on 14
    May; flows to the W had already cooled by 14 May.

    On the index map of the Galapagos Islands, the largest island, Isabela, is
    ~ 130 km long and lies to the E of Fernandina island. "La Cumbre"-Spanish
    for the summit, peak, or top-has been mistakenly applied to the volcano,
    apparently because the summit was so labeled on an old map. The island has
    also been called Narborough. The index map is incomplete in its portrayal
    of both volcanoes and islands of the archipelago. Revised from Bulletin v.
    20, no. 1.

    Galapagos National Park workers in western Galapagos were apparently the
    first to witness the eruption, and IG technicians recognized it on
    satellite imagery. The University of Hawaii presents hotspot images on
    their website. Their GOES data lacked hotspots at 0930, but a clear and
    strong one had developed on the S flank by 0945. Francisco Dousdebes (of
    Metropolitan Touring) placed the eruption's start time at 0935. S-flank
    hotspots were comparatively extensive by 1015. The Washington VAAC issued
    their first full advisory at 1315. Their notices reported that the
    W-directed plume rose to ~5 km altitude, and the S-directed plume went to 9
    km; both were visible as late as 1745 on 13 May, depicting the leading
    portions of Fernandina' s ash plume more than 200 km from the volcano

    An overflight of the eruption on the 13th by the National Park resulted in
    a report by Patricio Ramon and Hugo Yepes, and the eruption was confirmed
    by Washington Tapia, director of the Galapagos National Park. That evening,
    Galapagos resident Greg Estes telephoned Dennis Geist to report that the
    eruptive source was a "circumferential vent near [the] summit, S side . . .
    6 km long with an eruptive zone 50 m across." It was uncertain how this
    fissure was related to the 1981 eruption site (figure 2 and Bulletin v. 9,
    no. 3). IG also noted that tephra had fallen on neighboring Isabela Island,
    in the areas of the volcanoes Wolf and Ecuador (~40 km from the vent,
    figure 1).

    Figure 2. A 2002 International Space Station photograph of Fernandina,
    looking obliquely towards the E (N is towards the left). Labels show key
    features developed in 1995, 1981, and 1968 eruptions. Note the island's
    coastline in the lower-right corner and along much of the left margin.
    Despite the steep walls bounding the 850 m deep, 5 x 6.5 km central
    caldera, it supports both animal and plant populations. Image ISS05E06997
    (Visible Earth v1 ID 18002) with contrast enhanced and labels added by
    Bulletin editors.

    At 0537 on the second morning, 14 May, the Washington VAAC reported low
    level ash/steam not visible in infrared imagery, but at 0746, 1½ hours
    after sunrise, a plume of ash extended ~130 km to the W and was moving at
    18 km/hour at 1,800 m elevation. The GOES thermal anomaly was greatly
    diminished by 0930, and remained low to non-existent until resumption
    around 1415. That afternoon, an overflight by Godfrey Merlen, Wacho Tapia,
    and Alan Tye (Charles Darwin Research Station) resulted in the fullest
    report to date.

    They said that although the vent area was obscured by clouds, topography
    suggested a 4.5 km long fissure vent near the S rim, with activity having
    progressed from SW (near the first and uppermost flows of the 1995 radial
    fissure eruption) to the E (figure 1). The lava flows "had begun to pond on
    the gentler outer skirt of the island," and were then 5.5 km from the coast
    (~5 km from the vents). They thought it unlikely that the flows would reach
    the sea. A follow-up news report in El Comercio (Quito) quoted Tapia as
    identifying five flows down the S flank. Only one remained incandescent. At
    1745 on 14 May, Washington VAAC reported a plume remaining to the NW,
    but-lacking detectable ash-they discontinued advisories. Thermal anomalies
    on the GOES satellite remained strong, however, until the next morning.

    The report also noted that, "As on previous eruptions, such as that on
    Cerro Azul in 1998, lava passing through vegetated areas has caused small
    fires, but these have not spread far from the lava tongues themselves
    before going out. Most of the new flows have passed over unvegetated older
    lava, and damage to Fernandina's vegetation is limited."

    The team also flew over Alcedo volcano on Isabela, where Project Isabela
    staff had reported increased fumarole activity. Steam was rising from the
    "new" fumarole sites (active since the 1990s) and from the area of sulfur
    deposits and fumaroles in the southwestern area of the rim, but this
    activity did not appear unusual.

    On 15 May, the GOES thermal anomaly was gone before noon, but returned near
    midnight (about 2330), over a smaller area, and it remained through sunrise
    (0615) on 16 May. Small anomalies were visible the next several nights
    (when contrast with adjacent cold flows was strongest), but there was no
    obvious evidence of continued feeding of the new flows.

    The complex thermal anomalies detected in MODIS satellite imagery (provided
    by the University of Hawaii), were abundant around the time of eruption.
    They spread over Fernandina's rim, in some cases in the caldera, and
    broadly over the S flank. They continued through at least the rest of May.

    The Washington VAAC reported that a weak hotspot started 29 May 2005 at
    1945 (30 May at 0145 UTC) and a very short narrow plume of ash and gases
    appeared in multi-spectral imagery at 2145 (30 May at 0345 UTC). No ground
    confirmation of an eruption was available, and there was a layer of
    low-level weather cloud over the island. At that time, the plume appeared
    to dissipate as it moved away at ~18 km/hour.

    Background. Fernandina, the most active of Galapagos volcanoes and the one
    closest to the Galapagos mantle plume, is a basaltic shield volcano with a
    deep 5 x 6.5 km summit caldera. The volcano displays the classic
    "overturned soup bowl" profile of Galapagos shield volcanoes. Its caldera
    is elongated in a NW-SE direction and formed during several episodes of
    collapse. Circumferential fissures surround the caldera and were
    instrumental in growth of the volcano. Reporting has been poor in this
    uninhabited western end of the archipelago and even a 1981 eruption was not
    witnessed at the time. In 1968 the caldera floor dropped 350 m following a
    major explosive eruption. Subsequent eruptions, mostly from vents located
    on or near the caldera boundary faults, have produced lava flows inside the
    caldera as well as those in 1995 that reached the coast from a SW-flank
    vent. Collapse of a nearly 1 km³ section of the E caldera wall during an
    eruption in 1988 produced a debris-avalanche deposit that covered much of
    the caldera floor and absorbed the caldera lake.

    Information Contacts: Patricio Ramon and Hugo Yepes, Geophysical Institute
    (IG), Escuela Politecnica Nacional, Apartado 17-01-2759, Quito, Ecuador
    (URL: www.igepn.edu.ec/); Alan Tye, Charles Darwin Research Station,
    Puerto Ayora, Santa Cruz, Galapagos Islands, Ecuador (URL:
    www.darwinfoundation.org/); Washington Volcanic Ash Advisory Center
    (VAAC), Satellite Analysis Branch, NOAA/NESDIS E/SP23, NOAA Science Center
    Room 401, 5200 Auth Road, Camp Springs, MD 20746 USA (URL:
    www.ssd.noaa.gov/); Tom Simkin, Dept. of Mineral Sciences, National
    Museum of Natural History, Smithsonian Institution, Washington, DC
    20013-7012, USA (Email: simkin@nmnh.si.edu); National Earthquake
    Information Center, U.S. Geological Survey, Box 25046, DFC, MS 966, Denver,
    CO 80225-0046, USA (neic.usgs.gov/); MODIS Thermal Alert System;
    University of Hawaii and Manoa, 168 East-West Road, Post 602, Honolulu, HI
    96822, USA (URL: modis.higp.hawaii.edu).


    Anatahan
    Mariana Islands, USA
    16.35°N, 145.67°E; summit elev. 788 m
    All times are local (= UTC + 10 hours)

    Anatahan's third historical eruption began on 5 January 2005, and is
    described in Bulletin v. 29, no. 12. Further details and satellite images
    were presented in Bulletin v. 30, no. 2, which covered events until
    mid-February 2005. A 5-6 April 2005 eruption cloud rose to at least 15 km
    altitude, which was the highest yet seen at the volcano.

    Anatahan erupted almost continuously after 5 January 2005, when it started
    its third eruption in recorded history. An image collected by the Ozone
    Monitoring Instrument on NASA's Aura satellite shows atmospheric sulfur
    dioxide (SO2) concentrations between 31 January and 4 February 2005 (figure
    3). A long SO2 plume extends NE and SW of Anatahan, and the edge of the
    plume covers Guam (the southernmost island) and the other Mariana Islands
    immediately to Anatahan's N and S.

    Figure 3. Anatahan's atmospheric SO2 as imaged by Aura's OMI instrument on
    31 January 2005. The OMI (Ozone Monitoring Instrument) measures SO2 in
    Dobson Units. Dobson Units, which derive from spectroscopic measurement
    techniques, can be thought of as the mass of molecules per unit area of
    Earth's atmospheric column. One Dobson Unit equals 0.0285 grams of SO2 per
    square meter. The Ozone Monitoring Instrument (OMI) that created this image
    tracks global ozone change and monitors aerosols like sulfates in the
    atmosphere. It was added to the Aura satellite as part of a collaboration
    between the Netherlands' Agency for Aerospace Programs and the Finnish
    Meteorological Institute. NASA describes the Eos system Aura as "A mission
    dedicated to the health of the Earth's atmosphere." NASA image courtesy
    Simon Carn (Joint Center for Earth Systems Technology (JCET), University of
    Maryland Baltimore County (UMBC)).

    Volcanogenic SO2 combines with water to create a sulfuric acid haze. Called
    "vog," this haze can cause illness and make breathing difficult. Volcanic
    haze grew so thick during the first week of February that the National
    Weather Service issued a volcanic haze advisory for Guam, where several
    illnesses were reported.

    After mid-February 2005, eruptive activity at Anatahan steadily declined to
    less than 5% of the peak level attained since the eruption started on 5
    January. Ash eruptions continued, and the 2003 crater floor was almost
    entirely covered by fresh lava out to a diameter of ~1 km. A MODIS image
    taken at 0115 on 18 February showed a plume of steam and vog extending
    about ~170 km SW of Anatahan. Seismic and acoustic records during the last
    week of February 2005 showed very low levels of activity. Seismic
    amplitudes during 23-28 February were similar to those recorded prior to
    the 5 January eruption. NASA MODIS (Moderate Resolution Imaging
    Spectroradiometer) imagery taken on 28 February showed a faint plume of vog
    and steam trending W of Anatahan.

    During the first two weeks of March 2005 volcanic and seismic activity
    increased relative to the previous weeks. During 14-17 March, seismicity
    increased and steam rose a few hundred meters above the volcano. The inner
    E crater had been nearly filled with lava flows and lapilli since early
    January.

    A small eruption began on 18 March at 1544 according to seismic data. On 19
    March the Washington VAAC issued an advisory that an ash plume was visible
    on satellite imagery below 4 km altitude. Small explosions that began late
    on 20 March lasted for 14 hours. No emissions were visible on satellite
    imagery, but others were, later in March and April.

    A strong outburst apparently began on 21 March, a day when seismicity
    increased significantly. Seismic amplitudes peaked on the 25th and faded
    out on the 26th. Near the peak on the 25th, the U.S. Air Force Weather
    Agency (AFWA) detected a hot spot on the island on satellite imagery and
    reported an ash plume briefly reaching ~5.8 km altitude. The plume height
    soon dropped to below 3 km altitude, and by near midday on the 27th the
    plume had changed from ash and steam to steam and vog. On the 27th the
    plume extended ~240 km SW.

    On 5 April at about 2200 seismic signals began to increase slowly, and the
    Washington VAAC began to see increased ash on satellite imagery. On 6 April
    2005 around 0300 an explosive eruption began and produced an ash plume to
    an initial height of ~15.2 km altitude, the highest in recorded history
    from the volcano. Seismicity peaked at the same time.

    The AFWA reported an upper level ash plume at ~15.2 km altitude blowing E
    to SE and a lower level ash plume at ~4.6 km altitude blowing SW; the upper
    plume extended more than 465 km. Earth Probe TOMS data on 6 April at 1046
    showed a compact sulfur-dioxide cloud drifting E of Anatahan following the
    eruption.

    Chuck Sayon, the superintendent of American Memorial Park noted, "On Saipan
    at around 10 AM the skies darkened and light ash started falling . . . park
    operation[s] have been restricted to indoor activities due to irritation to
    eyes and breathing as ash starts to lightly coat the area. Schools are
    closed as well as the airport until further notice . . .."
    On 6 April during 0400 to 0900 the seismicity at Anatahan decreased to near
    background. The seismicity surged for about 1 hour, with amplitudes about
    one-half those reached during the earlier eruption, and subsequently
    dropped again to near background. Prior to the 6 April eruption, during 31
    March to 4 April the amplitudes of harmonic tremor varied, reaching a
    2-month high on the 3rd. Small explosions occurred every one minute to
    several minutes, probably associated with cinder-cone formation.
    Steam-and-ash plumes drifted ~200 km, and vog drifted ~400 km at altitudes
    below ~2.4- 4.6 km.

    The U.S. Geological Survey (USGS) (in conjunction with the Commonwealth of
    the Northern Mariana Islands) stated that the "eruption of 6 April 2005 was
    the largest historical eruption of Anatahan and expelled roughly 50 million
    cubic meters of ash. The eruption column and the amplitude of harmonic
    tremor both grew slowly over about 5 hours and both peaked about 0300 on 6
    April local time . . .. The peak of the eruption lasted about one hour and
    then the activity declined rapidly over the following hour."

    The 6 April 2005 eruption's plume was captured on satellite images. The
    image showed a plume that was tan or brown in color and clearly ash laden
    (figure 4).

    Figure 4. A major eruption from Anatahan on 6 April 2005 sent an ash plume
    to ~ 15 km. The eruption was considered the largest since Anatahan's first
    recorded eruption on 10 May 2003. This Moderate Resolution Imaging
    Spectroradiometer (MODIS) image was acquired by NASA's Terra satellite at
    0035 UTC, about 8 hours after the eruption began. By this time, the ash
    plume had spread S to entirely cover Saipan and Tinian, islands immediately
    to the S. Courtesy of the MODIS Rapid Response Image Gallery, sponsored in
    part by NASA.

    Figure 5 shows SO2 concentrations in the atmosphere on 7 April 2005, over
    30 hours after the large 6 April eruption. SO2 emissions from the eruption
    were measured by the Ozone Monitoring Instrument (OMI) on NASA's EOS/Aura
    satellite. OMI detects the total column amount of SO2 between the sensor
    and the Earth's surface and maps this quantity as it orbits the planet. A
    new perspective on the vertical distribution of the SO2 is revealed by
    combining the OMI data with coincident measurements made by the Microwave
    Limb Sounder (MLS), also part of the Aura mission.

    Figure 5. Anatahan's 5-6 April 2005 eruption injected significant SO2 high
    into the atmosphere. This OMI image depicts the concentrations found over
    30 hours after the eruption, a time when the SO2 formed two separate zones
    at distance from the source. Analysis suggests that the westerly zone of
    SO2 was probably in the lower troposphere and the eastern zone was probably
    in the upper troposphere or above. Courtesy of Simon Carn.

    The MLS data crisscross the OMI image and clearly show that some, but not
    all, of the SO2 measured by OMI to the volcano's E was in the upper
    troposphere or above. At these altitudes, SO2--and the sulfate aerosols
    that form from it--can stay in the atmosphere and affect the climate for a
    longer period of time. A weaker SO2 signal was also measured in the same
    region during the nighttime MLS overpass, which crosses the image from
    upper right to lower left. The daytime data, running from upper left to
    lower right, coincide with the OMI measurements. The MLS data west of
    Anatahan show no significant SO2 signal, indicating that the SO2 measured
    by OMI in this region was in the lower troposphere.

    MLS measures thermal emissions from the Earth's limb, so unlike the OMI
    sensor it also collects data at night. It is designed to measure vertical
    profiles of atmospheric gases that are important for studying the Earth's
    ozone layer, climate, and air quality, such as SO2. These images, derived
    from preliminary, unvalidated OMI and MLS data, show MLS SO2 columns
    (filled circles) measured every 165 km along the Aura orbit, plotted over
    the OMI SO2 map. The MLS SO2 columns shown here are derived from profile
    measurements made from the upper troposphere into the stratosphere (~215-0
    hPa (hectoPascal, 10^2 Pa) or ~12 km altitude and above), and the circles
    do not represent the actual size of the MLS footprint, which is roughly 165
    x 6 km.

    Anatahan's morphological changes were highlighted in before (pre-eruption)
    versus after (post-eruption) images. Seismicity decreased at Anatahan after
    6 April and during 7-11 April was at very low levels, near background. On
    11 April, a steam-and-ash plume rose ~2.7 km altitude and drifted ~280 km WSW.

    Occasional data from Anatahan revealed that seismicity appeared to increase
    during 24-25 April. During 20-25 April, a continuous thin plume of
    ash-and-steam rose to less than ~3 km altitude and drifted more than 185 km
    from the volcano. Harmonic tremor dropped dramatically on 1 May after being
    at high levels for several days. During 27 April to 1 May, the main
    ash-and-steam plume rose to ~3 km altitude According to a news article, the
    volcanic plume from Anatahan reached Philippine airspace on 4 May.

    On 5 May an extensive ash-and-steam plume to 4.5 km altitude was visible in
    all directions. Ash extended 770 km N, 130 km S (to northern Saipan), and
    110 km W. Vog extended in a broad swath from 3,000 km W, over the
    Philippines, to 1,000 km N of Anatahan. By 9 May harmonic tremor amplitude
    had decreased to near-background levels, with a corresponding drop in
    eruptive activity. As of 10 May AFWA was reporting ash to about 3 km
    altitude extending 400 km W and an area of vog less than half that noted on
    5 May.

    On 11 May AFWA reported thick ash rising to 4.2 km altitude and moving WNW.
    The thick ash extended in a triangular shape from the summit 444 km to the
    WSW through 510 km to the NW. A layer of thin ash at 3 km altitude extended
    another 1,000 km beyond the thick ash. A broad swath of vog extended over
    2,200 km W nearly to the Philippines and over 1,400 km NNW of Anatahan.
    Although the ash plume diminished over the next few days and was not as
    thick, it remained significant, rising to 2.4 km and extending 370 km WNW
    on the 13th. Scientific personnel from the Emergency Management Office and
    the USGS working the next day at a spot 2-3 km W of the active vent heard a
    continuous roaring sound. They also saw ash and steam rising by pure
    convection, not explosively, to 3 km altitude.

    Background. The elongated, 9-km-long island of Anatahan in the central
    Mariana Islands consists of two coalescing volcanoes with a 2.3 x 5 km,
    E-trending summit depression formed by overlapping summit calderas. The
    larger western caldera is 2.3 x 3 km wide and extends E from the summit of
    the western volcano, the island's 788-m-high point. Ponded lava flows
    overlain by pyroclastic deposits fill the caldera floor, whose SW side is
    cut by a fresh-looking smaller crater. The summit of the lower eastern cone
    is cut by a 2-km-wide caldera with a steep-walled inner crater whose floor
    is only 68 m above sea level. Sparseness of vegetation on the most recent
    lava flows on Anatahan indicated that they were of Holocene age, but the
    first historical eruption of Anatahan did not occur until May 2003, when a
    large explosive eruption took place forming a new crater inside the eastern
    caldera.

    Reference: Chadwick, W.W., Embley, R.W., Johnson, P.D., Merlea, S.G.,
    Ristaub, S., and Bobbitta, A., 2005, The submarine flanks of Anatahan
    volcano, Commonwealth of the Northern Mariana Islands: Jour. of Volcanology
    and Geothermal Res. (In press, June 2005).

    Information Contacts: Juan Takai Camacho and Ramon Chong, Emergency
    Management Office of the Commonwealth of the Northern Mariana Islands
    (CNMI/EMO), PO Box 100007, Saipan, MP 96950, USA (URL:
    www.cnmiemo.org/; Email: juantcamacho@hotmail.com and
    rcchongemo@hotmail.com); Simon Carn, Joint Center for Earth Systems
    Technology (JCET), University of Maryland Baltimore County (UMBC), 1000
    Hilltop Circle, Baltimore, MD 21250, USA; Hawaiian Volcano Observatory
    (HVO), U.S. Geological Survey, PO Box 51, Hawaii National Park, HI 96718,
    USA (URL: hvo.wr.usgs.gov/; Email: hvo-info@hvomail.wr.usgs.gov);
    Charles Holliday, U.S. Air Force Weather Agency (AFWA), Offutt Air Force
    Base, Nebraska 68113, USA (Email: Charles.Holliday@afwa.af.mil); Randy
    White and Frank Trusdell, U.S. Geological Survey, 345 Middlefield Road,
    Menlo Park, CA 94025-3591 USA (URL hvo.wr.usgs.gov/cnmi/update.html;
    Email: rwhite@usgs.gov; trusdell@usgs.gov,); Saipan Tribune, PMB 34, Box
    10001, Saipan, MP 96950, USA (URL: www.saipantribune.com/);
    Operational Significant Event Imagery (OSEI) team, World Weather Bldg.,
    5200 Auth Rd Rm 510 (E/SP 22), NOAA/NESDIS, Camp Springs, MD 20748, USA
    (URL: www.osei.noaa.gov/, Email: osei@noaa.gov); Washington Volcanic
    Ash Advisory Center (VAAC), Satellite Analysis Branch, NOAA/NESDIS E/SP23,
    NOAA Science Center Room 401, 5200 Auth Road, Camp Springs, MD 20746 USA
    (URL: www.ssd.noaa.gov/); Chuck Sayon, American Memorial Park,
    Saipan, MP 96950, USA; NASA's Earth Observatory (URL:
    earthobservatory.nasa.gov/).


    Vailulu'u
    Samoan Islands, USA
    14.21°S, 169.06°W; summit elev. -590 m

    According to Hubert Staudigel (Scripps Institution of Oceanography) and
    Stanley Hart (Woods Hole Oceanographic Institute), Vailulu'u seamount, the
    most active Samoan submarine volcano, erupted between April 2001 and April
    2005. It formed a 293-m-tall lava cone, which was named Nafanua after the
    Samoan Goddess of War. This new cone had been growing inside the 2-km-wide
    caldera of Vailulu'u at a minimum rate of about 20 cm/day since April 2001.
    Nafanua was discovered during a 2005 diving expedition with the National
    Oceanic and Atmospheric Agency (NOAA) research submersible Pisces V,
    launched from the University of Hawaii research vessel Kaimikai O Kanaloa
    (KOK). It is located in the originally 1,000-m-deep W crater of Vailulu'u
    (figures 6 to 9).

    Figure 6. The route of the 2005 cruise of the research vessel Kilo Moana.
    Vailulu'u, towards the E end of the Samoan hotspot trail was visited on
    cruise days 1-4, 4-8 April 2005. Courtesy of H. Staudigel and S. Hart.

    Figure 7. Bathymetry of Vailulu'u and nearby Ta'u Island, based on a
    SeaBeam bathymetric survey performed during R/V Melville's AVON 2 and 3
    cruises, augmented with satellite-derived bathymetry from Smith and
    Sandwell (1996). The inset shows the general location of Vailulu'u with
    respect to the Samoan Archipelago; two other newly mapped and dredged
    seamounts (Malumalu and Muli, AVON 3 cruise) are shown as well. Scale: 10'
    = 18 km. From Hart and others (2000).

    Figure 8. Bathymetry of the Vailulu'u crater between the 1999 and 2005
    surveys, showing the emergence of Nafanua. Courtesy of H. Staudigel and S.
    Hart.

    Figure 9. Bathymetric map of the Vailulu'u seamount from multibeam data
    during the April 2005 survey. Note the new inner cone named Nafanua.
    Contour interval is 20 m. Courtesy of H. Staudigel and S. Hart.

    Seismic monitoring during April-June 2000 showed substantial seismicity, ~4
    earthquakes per day with hypocenters beneath Nafanua (Konter and others,
    2004; Bulletin v. 26, no. 6), which can now be interpreted as pre-eruption
    seismic activity. These observations are consistent with previous reports
    highlighting the volcanic and hydrothermal activity of Vailulu'u (Hart and
    others, 2000; Staudigel and others, 2004). The scientists suggested that
    continued volcanic activity could bring the summit region of Vailulu'u to a
    water depth of ~200 m. At that point, Nafanua would overtop the crater rim
    and further growth would require a build-up of the lower flanks, areas that
    rise from the 5,000-m-deep floor of the ocean.

    Staudigel and Hart teamed up in April 2005 on the Hawaiian Research Vessel
    Kilo Moana to study the Samoan hotspot thought to underlie Vailulu'u. They
    named their expedition ALIA after the ancient twin-hulled canoe that Samoan
    warriors used to explore the SW Pacific. The Kilo Moana left Pago Pago on 4
    April 2005 to study active and extinct underwater volcanoes along the chain
    of Samoan islands. The expedition investigated previously uncharted
    seamounts and the submarine portions of some islands, scattered over almost
    600 nautical miles, from its most recent and quite active Vailulu'u
    submarine volcano in the E to Combe Island in the W.

    The Nafanua cone was first mapped by using the center beam of the research
    vessel KOK in several crossings of the W crater. An active hydrothermal
    system was apparent from evidence such as the murky water that limited
    visibility during two submersible dives, several microbial biomats covering
    pillow lavas that were centimeters thick, and a large number of diffuse
    vents. A dive on 30 March 2005 to examine Nafanua reported "that it must
    have grown in the last 4 years because CTD (conductivity-temperature-depth)
    crossings in 2001 still were consistent with the old crater morphology ...
    the basal portion of the cone displayed relatively large pillows, and
    higher up pillows look almost like very fluid pahoehoe that collapsed
    and/or transitioned into aa flows. Nafanua . . . grew very fast with
    abundant breccia material from collapsing and draining pillows, in
    particular in the summit region."

    On 1 April, another dive along the outer flanks of Vailulu'u found that
    during the up-slope transit, observers saw a few additional areas of active
    venting and many sites where there had been venting in the past. Large and
    perfectly formed pillow lavas were present in most sites, with a few areas
    being dominated by broken talus fragments and some having completely black
    glassy pillows with no oxidation, apparent evidence for relatively recent
    formation. The topography was extremely rough, the slope being punctuated
    with numerous fissure systems and edifices of pillow lava.

    A primary plan for the ALIA expedition was to study the water in and around
    the seamount for several days using a CTD probe. To sample the inside of
    the volcano for a full tidal cycle, the scientists varied the depth of the
    CTD between 40 and 930 m (almost to the crater floor), collecting various
    data, including visibility. At Vailulu'u, the particulates given off by
    hydrothermal venting are flushed out of its caldera during each tidal cycle
    into the surrounding water. In 2005, a dense layer of particulates was
    found in the water within the crater, but the water was clear outside the
    crater rim. This contrasts with observations seen from the cruise in 2000,
    when there was a dense ring of particulates around the whole volcano. It
    appears that in 2005 the particulates were rising above the crater and then
    later sinking, instead of forming the widespread ring observed in 2000.

    In addition, the expedition crew conducted dredging of the new summit of
    Nafanua. Staudigel and Hart noted that the rocks from the first dredge haul
    were quite newly formed, containing pristine olivine-phyric volcanic rocks.
    Abundant large vesicles in the rocks from Nafanua suggest a volatile-rich
    magma capable of submarine lava fountaining and explosive outgassing in
    shallower water. Dredging from a second site, outside of Vailulu'u,
    recovered rocks that were both much older and far less fragile.

    Background. A massive volcanic seamount, not discovered until 1975, rises
    4,200 m from the sea floor to a depth of 590 m about one-third of the way
    between Ta'u and Rose islands at the eastern end of the American Samoas.
    The basaltic seamount, named Vailulu'u, is considered to mark the current
    location of the Samoan hotspot. The summit of Vailulu'u contains a
    2-km-wide, 400-m-deep oval-shaped caldera. Two principal rift zones extend
    east and west from the summit, parallel to the trend of the Samoan hotspot,
    and a third less prominent rift extends SE of the summit. The rift zones
    and escarpments produced by mass wasting phenomena give the seamount a
    star-shaped pattern. On July 10, 1973, explosions from Vailulu'u were
    recorded by SOFAR (hydrophone records of underwater acoustic signals). An
    earthquake swarm in 1995 may have been related to an eruption from the
    seamount. Turbid water above the summit shows evidence of ongoing
    hydrothermal plume activity.

    References: Hart, S.R., Staudigel, H., Koppers, A.A.P., Blusztajn, J.,
    Baker, E.T., Workman, R., Jackson, M., Hauri, E., Kurz, M., Sims, K.,
    Fornari, D., Saal, A., and Lyons, S., 2000, Vailulu'u undersea volcano: The
    new Samoa: Geochemistry, Geophysics, Geosystems (G3), American Geophysical
    Union, v. 1, no. 12, doi: 10.1029/2000GC000108.

    Konter, J.G., Staudigel, H., Hart, S.R., and Shearer, P.M., 2004, Seafloor
    seismic monitoring of an active submarine volcano: Local seismicity at
    Vailulu'u Seamount, Samoa: Geochemistry, Geophysics, Geosystems (G3),
    American Geophysical Union, v. 5, no. 6, QO6007, doi: 10.1029/2004GC000702.

    Lippsett, L., 2002, Voyage to Vailulu'u: Searching for Underwater
    Volcanoes. Woods Hole Oceanographic Institution, Fathom online magazine
    (URL: www.fathom.com/feature/122477/).

    Staudigel, H., Hart, S.R., Koppers, A., Constable, C., Workman, R., Kurz,
    M., and Baker, E.T., 2004, Hydrothermal venting at Vailulu'u Seamount: The
    smoking end of the Samoan chain: Geochemistry, Geophysics, Geosystems (G3),
    American Geophysical Union, v. 5, no. 2, QO2003, doi: 10.1029/2003GC000626.

    Information Contacts: Hubert Staudigel, Institute of Geophysics and
    Planetary Physics, Scripps Institution of Oceanography, Univ. of
    California, San Diego, La Jolla, CA 92093-0225, USA (Email:
    hstaudigel@ucsd.edu; URL:
    earthref.org/PACER/team/...audigel.htm;
    igpp.ucsd.edu); Stanley R. Hart, Woods Holes Oceanographic
    Institute, Geology and Geophysics Dept., Woods Hole, MA 02543, USA (Email:
    shart@whoi.edu); ALIA Expedition, Samoan Seamounts, R/V Kilo Moana
    (KM0506), supported by the San Diego Supercomputer Center and the Scripps
    Institution of Oceanography (URL: earthref.org/ERESE/projects/ALIA/).


    Awu
    Great Sangihe Island, Indonesia
    3.67°N, 125.50°E; summit elev. 1,320 m
    All times are local (= UTC + 8 hours)

    Awu's eruption on 6 June 2004 and its elevated seismicity in early August
    2004 was previously reported (Bulletin v. 29, no. 10). This report covers
    the last half of August 2004, which had not been reported on previously.
    Since the 6 June eruption, observation of the summit failed to reveal any
    significant changes (table 1). The hazard status of Awu during this August
    report remained at Level 2, having been elevated to 4 (the highest on a
    scale of 1 to 4) at the time of the 6 June eruption and then lowered on 14
    June.

    Table 1. Seismicity at Awu during August 2004 as reported by DVGHM.

    Date Volcanic A Volcanic B Tectonic

    08 Aug-15 Aug 2004 -- -- 75
    16 Aug-22 Aug 2004 2 1 81
    23 Aug-29 Aug 2004 2 -- 102

    Background. The massive Gunung Awu stratovolcano occupies the northern end
    of Great Sangihe Island, the largest of the Sangihe arc. Deep valleys that
    form passageways for lahars dissect the flanks of the 1,320-m-high volcano,
    which was constructed within a 4.5-km-wide caldera. Awu is one of
    Indonesia's deadliest volcanoes; powerful explosive eruptions in 1711,
    1812, 1856, 1892, and 1966 produced devastating pyroclastic flows and
    lahars that caused more than 8,000 fatalities. Awu contains a summit crater
    lake that was 1 km wide and 172 m deep in 1922, but was largely ejected
    during the 1966 eruption.

    Information Contacts: Dali Ahmad, Directorate of Volcanology and Geological
    Hazard Mitigation (DVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia
    (Email: dali@vsi.dpe.go.id; URL: www.vsi.dpe.go.id).


    Karthala
    Grand Comore Island, Comoros
    11.75°S, 43.38°W; summit elev. 2,361 m
    All times are local (= UTC + 3 hours)

    After a long period of quiescence following the 1991 phreatic eruption,
    Karthala's seismicity rebounded starting in July 2000 (Bulletin v. 25,
    no.10). In October 2000, more than 20 seismic events per day were recorded.

    The local observatory and a key source for this report is the Karthala
    Volcano Observatory (KVO; Netter and Cheminee, 1997). They maintain close
    ties with the Centre National de Documentation et de Recherche Scientifique
    des Comores (CNDRS), Reunion Island University, the Institut de Physique du
    Globe de Paris, Piton de la Fournaise Volcanological Observatory, and
    various universities in France.

    Activity during October 2000-March 2004. Between October 2000 and January
    2003, relatively low seismicity was detected beneath Karthala's summit. The
    seismicity slowly increased. During January instruments recorded 51
    earthquakes on the 5th, 58 on the 10th, and 50 on the 11th. During the
    month of April 2003 instruments registered 732 (i.e. averaging ~24 each day).

    Seismic instruments detected several short earthquake swarms, each
    comprised of ~150 earthquakes. These swarms took place on 25 March and in
    April 2003, and each lasted several hours. Moreover, seismologists
    witnessed another swarm consisting of 183 events on 15 May. Except for that
    latter swarm, Karthala's seismicity was relatively quiet for 35 days after
    the 25 April swarm. A photo of the Chahale crater from the year 2003, well
    before the April 2005 eruption, appears in figure 10. (For a map of
    Karthala's summit, see Bulletin v. 16, no. 8.)

    Figure 10. Karthala's ~ 300-m-diameter Chahale crater as seen on 15 August
    2003, more than a year prior to the April 2005 eruption. The photo was shot
    by the automatic camera located at the summit, looking from the NNE towards
    the SSW. The 2005 eruption dramatically changed this scene, replacing the
    green lake seen here with a lava lake, and blanketing considerable areas
    with tephra. Courtesy of Nicolas Villenueve.

    During the time interval from early June 2003 to January 2004 instruments
    registered three periods with elevated seismicity. The first interval
    spanned 121 days from June until the end of September 2003 and included
    6,315 earthquakes. Within that interval there was a major crisis on 6th
    September, comprised of 345 events, some being felt by local residents
    (Bulletin v. 28, no. 8).

    The second interval began on 11 October 2003, reaching its peak on 4
    January 2004 (253 events) and stopped on 31 January 2004. During this
    interval of 113 days, instruments registered 4,431 earthquakes. The third
    interval, during the time period of 3 February to 5 March 2004, contained
    fewer earthquakes. Instruments recorded 832 events in 31 days with a
    maximum of 143 events per day. After the third interval, KVO recorded only
    low seismicity until early 2005, when daily events rose to 50-60.

    Eruption during April 2005. A seismic crisis began at 0812 on 16 April.
    Although instruments initially received only short-period events, starting
    at 0914 they also registered many long-period ones. From 1055 on 16 April a
    continuous signal was recorded, which was interpreted as tremor marking the
    beginning of the eruption. At around 1400 that day inhabitants heard a
    rumbling coming from the volcano. A few minutes later they observed an ash
    column above the summit. The first ash-fall deposits began to form around
    1600, developing on the island's eastern side. According to the firsts
    reports, ash deposition increased and continued through the night
    accompanied by a strong smell of sulfur.

    On the morning of 17 April ash falls continued on the eastern part of the
    island and were heavy enough to require inhabitants to use umbrellas to get
    about. At midday, Jean-Marc Heintz, a pilot for Comores Aviation, flew over
    the west flank and observed a large plume in the direction of the Chahale
    crater. He also clearly observed airborne molten ejecta.

    Around 1300, observers saw a very dark plume, spreading into a mushroom
    shape and accompanied by lightning flashes. Some inhabitants panicked and
    fled the island's eastern villages. In the afternoon, residents heard
    rumbling. During the evening, significant rainfall generated small
    mudflows, and the rumbling became stronger.

    At that time, authorities evacuated some eastern villages (according to
    Agence France Presse (AFP) this affected ~10,000 people). Ash there started
    to fall on the island's western and northern parts, notably, on the
    country's capital city of Moroni (~10 km NW of the summit) and on the
    Hahaya airport (~20 km N of Moroni, ~25 km NW of the summit). Figure 11
    shows a photo with the base of a vigorous plume over the E flanks on the
    afternoon of 17 April.

    Figure 11. A phreatic eruption as seen from Karthala's eastern slopes on
    the afternoon of 17 April 2005. The vent lies below the white-colored zone
    in the center-right portion of the photo. With enlargement, many parts of
    the image record the descent of large pieces of ejecta. Photo credit to
    school teacher Daniel Hoffschir.

    KVO authorities sometimes witnessed a red color at the plume's base,
    interpreted as a sign of an ongoing magmatic eruption. At 2105 the KVO
    seismic network recorded a drastic decrease in the amplitude of the tremor.
    During the night of 17-18 April, wide variations of the tremor amplitude
    were recorded with a maximum at 0140 on 18 April and a minimum at 0430 on
    18 April. Thereafter, the tremor amplitude did not increase. During the
    night of 17-18 April the plume and falling ash disappeared.

    On an overflight of the Chahale crater at 0830 on 18 April, KVO personnel
    observed major modifications at the summit (figures 12-14). A lava lake
    (figure 12) had replaced the water-bearing lake (figure 10) that had
    occupied the crater since 1991.

    Figure 12. On 18 April 2005 the Karthala eruption generated a lava
    lake in the Chahale crater. In this photo, taken the morning of 18 April,
    considerable portions of the lava lake's surface still remained molten and
    incandescent.. The lake's surface only remained molten for a few hours.
    This aerial photo was taken looking from the N. Courtesy of Hamid Soule.

    Figure 13. A 19 April 2005 aerial photograph of Karthala taken from the SE
    centered on Chahale crater. The lava lake's surface had chilled and it
    emitted white vapor. Much of the summit area displays the recently
    deposited smooth-surfaced tephra blanket. Courtesy of Nicolas Villenueve.

    Figure 14. Tephra deposits left by Karthala's mid-April 2005 eruption
    altered the landscape and destroyed vegetation. This picture was taken at
    the entrance to the first caldera on the western trail, viewed looking to
    the S. Courtesy of Nicolas Villenueve.

    On 19 April a new overflight revealed the crater floor containing the lava
    lake, with its chilled surface emitting steam (figure 13). Lava remained
    confined to Chahale crater. Around the caldera area, and particularly on
    its N, observers saw conspicuous tephra deposits; most of the vegetation
    had been destroyed (figure 14).

    On 20 April a field excursion found that ash deposits varied in thickness
    from a few millimeters on the coast to ~1.5 m at the summit. Near the
    summit the observers recognized some post-eruptive evaporation and
    geothermal processes. Specifically, although the lava lake's surface had
    frozen, there remained sufficient heat under the surface that groundwater
    migrating towards to the crater's floor evaporated into steam. During
    another field survey on 8 May, observers noted the renewed presence of lake
    water inside the crater.

    Background. The southernmost and largest of the two shield volcanoes
    forming Grand Comore Island (also known as Ngazidja Island), Karthala
    contains a 3 x 4 km summit caldera generated by repeated collapse.
    Elongated rift zones extend to the NNW and SE from the summit of the
    Hawaiian-style basaltic shield, which has an asymmetrical profile that is
    steeper to the south. The lower SE rift zone forms the Massif du Badjini, a
    peninsula at the SE tip of the island. Historical eruptions have modified
    the morphology of the compound, irregular summit caldera. More than twenty
    eruptions have been recorded since the 19th century from both summit and
    flank vents. Many lava flows have reached the sea on both sides of the
    island, including during many 19th-century eruptions from the summit
    caldera and vents on the northern and southern flanks. An 1860 lava flow
    from the summit caldera traveled ~13 km to the NW, reaching the western
    coast north of the capital city of Moroni.

    Reference: Netter, C., and Cheminee, J. (eds.), 1997, Directory of Volcano
    Observatories, 1996-1997: World Organization of Volcano Observatories
    (WOVO), WOVO/IAVCEI/UNESCO, Paris, 268 p.

    Information Contacts: Nicolas Villeneuve (CREGUR, Centre de Recherches et
    d'Etudes en Geographie de l'Universite de la Reunion), Hamidou Nassor, and
    Patrick Bachelery (LSTUR, Laboratoire des Sciences de la Terre), Universite
    de La Reunion BP 7151, 15 Avenue, Rene Cassin, 97715 Saint-Denis, Reunion
    Island (Email: Nicolas.Villeneuve@univ-reunion.fr;
    Patrick.Bachelery@univ-reunion.fr); Francois Sauvestre and Hamid Soule,
    CNDRS, BP 169, Moroni, Republique Federale Islamique des Comores (Email:
    obs_karthala@ifrance.com; URL:
    volcano.ipgp.jussieu.fr:8080/kar...ml).


    Ol Doinyo Lengai
    Tanzania, eastern Africa
    2.751°S, 35.902°E; summit elev. 2,960 m
    Al times are local (= GMT + 3 hours)

    Although lava venting at Ol Doinyo Lengai continued intermittently after
    February 2004 (Bulletin v. 29, no. 2), no significant changes were detected
    until July 2004, a time when vigorous venting emitted substantial amounts
    of the low-viscosity carbonatitic lava typical at this volcano ('flash
    floods' of lava). This summary report covers the time interval from
    February 2004 through early February 2005 based on observations made by
    Frederick Belton, Celia Nyamweru, Bernhard Donth, and Christoph Weber.
    Websites devoted to Ol Doinyo Lengai, including photographs, information on
    the evolution, recent history, and current status of the volcano are
    maintained by Belton, Nyamweru, and Weber.

    A map, thermal data, and some new elevation estimates. In February 2005
    Weber and others collected location data with a global positioning system
    (GPS) receiver. Weber used this to create a sketch map of the active crater
    (figure 15).

    Figure 15. Sketch map of crater features at Ol Doinyo Lengai surveyed with
    a global positioning system (GPS) during 3-7 February 2005. During the
    course of the report interval, new vents developed at T49G and T58C (amid
    the N-central group of hornitos; T49G sits ~ 10 m E of T49B). These new
    vents produced comparatively vigorous eruptions. Courtesy of Chris Weber
    (Volcano Expeditions International, VEI).

    In July 2004 Belton completed the third of a series of distance
    measurements across crater outflow areas at the crater rim (table 2). Due
    to the unusually strong eruption on 15 July 2004 (figure 16), deposits
    comprising the E overflow widened by 3 or 4 m (growing from 44 to 47 m,
    figure 15). Later, in January 2005, observers noticed a fourth area of
    overflows had become established on the N crater rim, with lavas pouring
    over the rim at two adjacent points there (figure 15).

    Table 2. For Ol Doinyo Lengai, the width of the three extant lava outflows
    at the points where they spilled from the active crater ('overflows,'
    figure 15), as measured during 2 August 2003-29 July 2004. Two additional
    small overflows formed later, by January 2005, on the N crater rim. The 3-m
    E-overflow increase occurred during the eruption of T58C on 15 July 2004.
    Courtesy of Frederick Belton.

    Crater rim Date of Width (m)
    overflow area measurement

    NW overflow 02 Aug 2003 135
    NW overflow 29 Jun 2004 135
    NW overflow 29 Jul 2004 135

    E overflow 02 Aug 2003 44
    E overflow 29 Jun 2004 44
    E overflow 29 Jul 2004 47

    W overflow 02 Aug 2003 17
    W overflow 29 Jun 2004 18
    W overflow 29 Jul 2004 18

    Figure 16. A time exposure photograph of Ol Doinyo Lengai taken just after
    sunset on 15 July 2004. At that time the newly formed vent T58C ("Charging
    Rhino") issued copious lava. This photo was taken looking approximately NW
    from the SE part of the crater rim. Courtesy of Frederick Belton.

    During 3-7 February 2005 Weber and others completed a series of lava and
    fumarole temperature measurements that appear as tables 3 and 4. The tables
    indicate the hottest lava and fumarole temperatures at cracks were 588°C
    (at T49C, February 2004) and 150°C (at T49G, June 2004), respectively. The
    hornitos T49C and T49G both lie near T49B, a hornito delineated on figure 15.

    Table 3. Repeated maximum lava temperatures measured at Ol Doinyo Lengai
    during 28 August 1999 to 3 February 2005. The measurements were made
    employing a digital thermometer (TM 914C with a stab feeler of standard K
    type). The instrument was used in the 0-1200°C mode, and at least four
    replicate measurements were made at any one spot. Calibration was by the
    delta-T method; uncertainties were +- 6°C in the 0-750°C range. Courtesy of
    C. Weber.

    Date Location
    Temperature (°C)

    28 Aug 1999 T40 lava
    lake 529
    01 Sep 1999 Pahoehoe flow in a tube near
    T40 519
    01 Sep 1999 Aa flow still in motion at flat terrains (60 cm
    thick) 516
    03 Oct 2000 Pahoehoe flow in a tube near
    T49B 507
    03 Oct 2000 Aa flow still in slow motion at flat terrain (25 cm
    thick) 496
    11 Feb 2004 Pahoehoe flow in a tube near
    T49G 588
    12 Feb 2004 Pahoehoe flow in a tube near
    T49B 579
    13 Feb 2004 Aa flow not in motion anymore at flat terrain (15 cm
    thick) 490
    26 Jun 2004 Pahoehoe flow in slow motion (10 cm thick) flat
    terrain 560
    03 Feb 2005 Pahoehoe flow (15 cm thick) in motion traveling within
    a levee. 561
    03 Feb 2005 Aa flow not in motion anymore at flat terrain (15 cm
    thick) 520

    Table 4. Maximum fumarole temperatures measured at cracks in Ol Doinyo
    Lengai's crater floor over a series of visits during 28 August 1999 to 4
    February 2005. Collected using the digital thermometer with procedures and
    parameters noted with the previous table. For locations, see map (figure
    15). Courtesy of C. Weber.

    Date Location Temperature (°C)

    28 Aug 1999 F1 70
    28 Aug 1999 Near T49 82
    03 Oct 2000 Near T49C 75
    03 Oct 2000 F1 69
    20 Oct 2002 The hottest cracks in the crater floor 124
    20 Oct 2002 F1 78
    30 Jun 2003 F1 86
    30 Jun 2003 Near T49C 76
    12 Feb 2004 F1 88
    26 Jun 2004 F1 78
    26 Jun 2004 Near T49C 150
    04 Feb 2005 F1 84

    Weber's team GPS measurements suggested a summit elevation of 2,960 +- 5 m.
    This is consistent with GPS measurements taken in October 2000, by a
    scientific group led by Joerg Keller, of 2,950-2,960 m (Bulletin v. 25, no.
    12). In addition, the tallest hornito in the N-central crater rises to
    nearly this elevation (see discussion of T49/T56B, below).

    During observations in February 2004, Weber measured the tallest hornito at
    the T49 location (part of T56B) in the center area of the active crater.
    GPS readings on top of T56B yielded an elevation of 2,886 m. This is only 4
    m below the elevation of the summit and within the stated, +- 5m
    uncertainty of that measurement. The top of T49 is also ~33 m above the
    adjacent crater floor to the N. In addition, when he measured on 3-7
    February, Weber found hornito T58C (a then recent feature) had grown to
    reach an elevation of ~2,870 m.

    Observations during February 2004 to February 2005. During February 2004
    visits, T56B did not erupt, but instead a new vent erupted at the T49
    location (~10 m E of T49B, see also Bulletin, v. 29, no. 2). This new vent
    was called T49G (figure 15).

    A group from Volcano Expeditions International (VEI) spent 24-30 June 2004
    on Lengai and found much of the scene at the vents in the crater similar to
    that noted in February 2004. They noted that half of the upper 10 m of
    hornito T56B had collapsed on its E side, and an active lava lake had
    formed inside this hornito with lava escaping several times through the
    collapsed opening to its E and flowing out ~200 m. The lava was rich in gas
    with a temperature of 560°C. The hornito T58B was also active and spattered
    lava many times during these days of observation. Some lava flows from T58B
    reached about 150 m to the S.

    During 2-3 July 2004, Belton observed T58B erupt repeatedly, emitting lava
    and strombolian displays. The escaping lava flowed S, passing near the base
    of hornito T47. On 4 July, Belton saw some of the most intense activity of
    the month. A sequence of lavas erupted on that day and over the next few
    days. However, events in mid-July and later were also unusually vigorous.

    The 4 July 2004 activity included strong strombolian eruptions at T58B and
    several collapses of its vent area, which released large cascades of lava
    onto the crater floor. Simultaneously, a tube-fed eruption of pahoehoe lava
    from the new vent T49G flowed across the NW crater rim to spill down that
    flank. Early on 5 July numerous eruptions of T58B sent lava flowing toward
    T47 at an estimated velocity of 10 m/sec. On 6 July, lava flowed out of the
    lake in T56B and onto the crater floor moving E and entering a cave in T45
    for a short distance.

    After very low activity during 7-10 July 2004, renewed flows and spatter
    came out on 11 July from T58B, and frequent but short (usually ~2 minute)
    episodes of loud degassing and spattering issued from the lava lake in
    T56B. At night, this vent emitted incandescent gas. This pattern continued
    until the morning of 14 July, when eruptions at T58B became more explosive
    and it expelled small ash clouds. On the morning of 15 July a collapse in
    the vent area of T58B released large rapid lava flows to the E. The
    episodes of degassing and spattering from T56B increased in frequency until
    1500 on 15 July, when a small hole formed in the crater floor just E of T58B.

    Called T58C, the hole became a newly opened vent. It began emitting visible
    gas puffs mixed with spatter. At this time the degassing episodes from T56B
    ceased. T58C then began strong degassing and squirted up intermittent lava
    fountains. The fountains soon fed a large lava stream moving toward the S
    crater wall.

    By 1600 on 15 July 2004 a paroxysm at T58C was in progress, with lava
    forming 10- to 12-m-tall fountains and 'flash floods' that completely
    inundated the central-eastern crater floor (in the area between T56B, T58B,
    T37, T37B, T45, and T57). T58C also ejected strong jets of ash and gas.
    Turbulent rivers of lava flowing at more than 10 m/sec swept toward the
    crater's S wall and its E overflow and completely surrounded T37B and T45.
    Flow rate from the vent was estimated to peak at 10 m^3/s.

    The momentum of the rapidly outflowing lava carried it nearly 3 m up the W
    (upstream) side of T45 and obliterated the large cave within that cone. The
    associated surge of lava poured over the E crater rim and down the flank.
    It flooded over a 3 m wide swath of vegetation. This triggered a huge cloud
    of steam and smoke that resembled a small pyroclastic flow. The smoke cloud
    was accompanied by a loud sizzling sound. A brush fire burned along the
    crater rim overflow as additional floods of lava arrived. These
    larger-than-normal flows lasted for little more than 30 sec and were
    separated by periods of repose of 5 to 6 min. After sunset, incandescent
    gas flared from the vent during the repose periods. Weak strombolian
    activity was seen in T56B.

    Early on 16 July 2004 the newly formed T58C was a circular pit ~2 m in
    diameter with lava sloshing violently at a depth of ~2 m. Two small
    sub-vents on the N and S edges of the pit interconnected with the main
    vent. Activity continued sporadically at T58B and T56B with strombolian
    activity and lava flows. On 21 July there was an exceptionally strong
    eruption of T58B with loud explosions, jetting of ash-poor clouds, and
    spatter thrown to above-average heights. Explosions blasted a new vent in
    the upper E side of T58B. At least four oval bombs 9-12 cm in length flew
    through the air, along with a great deal of lapilli and ash. Later
    examination of the bomb's interiors revealed that they all had an outer
    zone ~1.5- to 2-cm thick and a distinctive inner core.

    On 23 July 2004, a sloping ~4 m^2 oval section of the crater floor
    immediately SW of the new spatter cone T58C began to steam and vibrate.
    Tremor increased and ground movement was visible, manifested as a small
    section of crater floor rapidly pushed outward and then inward several
    centimeters, like a membrane vibrating in time to the degassing sounds of
    lava in T58C just behind it. Abruptly this portion of the crater floor
    broke outward, and a flood of lava ensued. T58C was observed to grow in
    height through the time when Belton left the crater on 29 July 2004.

    Observations during January and February 2005. Donth reported that during
    his visit on 10 January 2005, hornito T49B erupted to form many effusive
    lava flows. For the first time, lava escaped over the northern edge of the
    crater (see figure 15).

    During Weber's crater visit, 3-7 February 2005, the hornito T49B actively
    emitted lava flows that traveled to the N. Pahoehoe lava flows in motion
    within small levees on flat terrain were measured from 520°C up to a
    maximum of 561°C (table 3). The fumaroles at F1 had a maximum temperature
    of 84°C, and at hornito T46, a maximum of 91°C (table 4). No change in
    distance was measured across the CR1, CR2, and CR3 cracks cutting the upper
    crater walls. Adding to visitor safety concerns, which include altitude
    sickness, burns, falls, and impact from ejecta, Weber's team saw a spitting
    cobra close to the summit. An overflight by plane on 14 February showed no
    subsequent change, but did give an excellent view of the crater and its
    central hornitos (figure 16).

    A flight on 14 February failed to reveal subsequent changes. But the effort
    provided an excellent view of the crater and its central hornitos (figure 17).

    Figure 17. An aerial photograph taken looking towards the WSW at the summit
    crater of Ol Doinyo Lengai on 14 February 2005. The summit, which lies in
    the upper left corner has a revised elevation based on GPS (see text). In
    addition, GPS elevations and uncertainties suggest that in 2005 the summit
    was only marginally higher than the top of the tallest hornito (T56B).
    Copyrighted photo provided courtesy of T. Schulmeister and C. Weber.

    Background. The symmetrical Ol Doinyo Lengai stratovolcano is the only
    volcano known to have erupted carbonatite tephras and lavas in historical
    time. The prominent volcano, known to the Maasai as "The Mountain of God,"
    rises abruptly above the broad plain S. of Lake Natron in the Gregory Rift
    Valley. The cone-building stage of the volcano ended about 15,000 years ago
    and was followed by periodic ejection of natrocarbonatitic and nephelinite
    tephra during the Holocene. Historical eruptions have consisted of smaller
    tephra eruptions and emission of numerous natrocarbonatitic lava flows on
    the floor of the summit crater and occasionally down the upper flanks. The
    depth and morphology of the northern crater have changed dramatically
    during the course of historical eruptions, ranging from steep crater walls
    about 200 m deep in the mid-20th century to shallow platforms mostly
    filling the crater. Long-term lava effusion in the summit crater beginning
    in 1983 had by the turn of the century mostly filled the northern crater;
    by late 1998 lava had begun overflowing the crater rim.

    Information Contacts: Christoph Weber, Volcano Expeditions International,
    Muehlweg 11, 74199 Untergruppenbach, Germany (URL: www.v-e-i.de,
    Email: mail@v-e-i.de); Celia Nyamweru, Department of Anthropology, St.
    Lawrence University, Canton, NY 13617, USA (URL:
    it.stlawu.edu/~cnya/; Email: cnyamweru@stlawu.edu); Frederick
    Belton, Developmental Studies Department, PO Box 16, Middle Tennessee State
    University, Murfreesboro, TN 37132, USA (URL:
    www.oldoinyolengai.org, Email: oldoinyolengai@ hotmail.com); Bernard
    Donth (Email: b.donth@ saarschmiede.com).
    __________________________________________________________
    Global Volcanism Program, NHB E-421 Tel: (202) 633-1800
    Smithsonian Institution Fax: (202) 357-2476
    Washington, DC 20560-0119 Email: gvp@si.edu

    Internet: www.volcano.si.edu/
  • Re: GVN Bulletin

    Fri, July 15, 2005 - 2:13 PM
    ***************************************************
    Bulletin of the Global Volcanism Network, May 2005
    ***************************************************
    From: Ed Venzke <venzke@volcano.si.edu>


    Bulletin of the Global Volcanism Network
    Volume 30, Number 5, May 2005

    <www.volcano.si.edu/reports/...bgvn.pdf>

    Ambrym (Vanuatu) Steady emissions of SO2 create health problems, destroy
    crops, and contaminate water
    Manam (Papua New Guinea) Aircraft encounters airborne gas from 27 January
    2005 eruption; infrasonics
    Langila (Papua New Guinea) Ash emissions and lava flow during April-June 2005
    Egon (Indonesia) Three eruptions in February 2005 eject ash and gas
    Karangatang (Indonesia) Ongoing seismicity during January-February 2005;
    lava avalanche in January
    Barren Island (India) Lava flow and ash discharges seen by Coast Guard
    personnel on 28 May 2005
    Long Valley (USA) Minor seismicity throughout 2004
    Reventador (Ecuador) Lava flow reaches 4 km from summit, approaching road
    and petroleum pipeline
    Lascar (Chile) Further analysis of 4 May 2005 event indicates a
    phreato-Vulcanian eruption
    Rotorua (New Zealand) Hydrothermal eruption of 19 April 2005-one of the
    area's largest since 1948
    White Island (New Zealand) Seismic and hydrothermal activity remain low
    through June 2005

    Editors: Rick Wunderman, Catherine Galley, Edward Venzke, and Gari Mayberry
    Volunteer Staff: Robert Andrews, William Henoch, Clement Pryor, Jacquelyn
    Gluck, and Stephen Bentley



    Ambrym
    Vanuatu, SW Pacific
    16.25°S, 168.12°E; summit elev. 1,334 m
    All times are local (= UTC + 11 hours)

    Jenifer Piatt, a meteorologist with the Air Force Weather Agency in the
    Satellite Applications Branch, notified Bulletin staff on 17 June 2005 that
    haze had appeared near Ambrym on MODIS imagery over the past few days. Over
    the past several months, this volcano had been emitting SO2 and sometimes
    light ash. She informed us of several recent news articles that addressed
    this event and provided several satellite images (figure 1).

    Figure 1. Images for 0250 UTC 15 June 2005 (top), and 0240 UTC 17 June 2005
    (bottom) disclosing the area around Vanuatu including Ambryn. The images
    came from NASA's AQUA MODIS satellite with a resolution of 500 m. SO2
    plumes from Ambrym are labeled. NASA image courtesy of USAF Weather Agency.

    Tony Ligo wrote on 1 June 2005 in the Port Villa Presse that acid rain
    continued to fall in W Ambrym Island in Vanuatu, even after ash from the
    volcano had stopped falling. This prompted the provincial secretary general
    to discuss the need for new water sources. The Vanuatu government, through
    the department of Rural Water Supply, agreed to provide a drilling rig to
    the Malampa provincial government to drill on W Ambrym as soon as possible.

    The government also recognized the value of scientific and technical data;
    in order to effectively respond to such environmental problems the
    government needs to get more young people studying in this area. The
    article noted that Vanuatu only has one volcanologist, Charley Douglas,
    with enough background to give accurate data on current activity.

    Aid and food have been sent to affected areas on the western coast of the
    island, and a contingency evacuation plan is required for resettling people
    should this be necessary in the future. Health issues have been raised
    regarding hygiene, respiratory problems, asthma, and malnutrition over the
    past couple of months. Of great concern are health problems particular to
    children, including exposure to excess fluoride and the consequent risk of
    bone disease.

    The National Aeronautics and Space Administration (NASA) Earth Observatory
    web site reported that Ambrym volcano was the strongest point source of SO2
    on the planet for the first months of 2005; it had been steadily emitting
    SO2 for at least 6 months, and satellite images produced using data
    collected by the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite
    during the first 10 days of March 2005 show high concentrations of SO2
    drifting NW.

    The web site article noted that "Ambrym is not erupting in the traditional
    sense with thick ash plumes and explosive bursts of lava, rather it is
    leaking SO2 gas from active lava lakes in what scientists call 'passive"or
    "non-eruptive" emissions. Despite these gentle names, the volcano still
    threatens the local population. SO2 has a strong smell and can irritate the
    eyes and nose and make breathing difficult. Higher in the atmosphere, SO2
    combines with water to create rain laced with sulfuric acid. On Ambrym,
    acid rain has destroyed staple crops and contaminated the water supply,
    leaving communities in need of food aid." In the past, satellites have been
    able to monitor SO2 emissions only from large eruptions or the most
    powerful passive degassing. All other SO2 emissions remain at low altitudes
    and have low SO2 concentrations that were hard to see from space.

    On 15 July 2004, NASA launched its Aura satellite carrying the OMI, which
    is part of a collaboration between the Netherlands' Agency for Aerospace
    Programs, the Finnish Meteorological Institute, and NASA. With greater
    spatial resolution (the ability to "zoom-in" to see greater detail) and
    higher sensitivity to SO2 than any previous space-borne sensor, OMI allows
    scientists to study passive volcanic degassing on a daily basis for the
    first time.

    The image in figure 2 is an example of the instrument's preliminary,
    uncalibrated, and unvalidated data. This new view of passive volcanic
    emissions could lead to significant advances in understanding both volcanic
    eruptions and the impact of SO2 on climate. Changes in passive emissions
    can be a precursor to explosive eruptions, and thus provide a warning
    signal that activity may be changing.

    Figure 2. A zone of elevated atmospheric SO2 from Ambrym during
    the interval 1-10 March 2005. The units on the scale bar reflect SO2 in
    terms of Dobson Units (DU). (A Dobson Unit represents the physical
    thickness of the SO2 gas if a 1 cm2 column of the atmosphere were brought
    to 0EC and 1 atmosphere pressure. A value of 300 Dobson Units equals three
    millimeters.) To process the OMI spectrometer data, two different pairs of
    measured UV wavelengths are averaged. The mean of pairs 1 and 2 is
    written as "P1-P2 mean" on the scale bar. Courtesy of Simon Carn.

    Background. Ambrym, a large basaltic volcano with a 12-km-wide caldera, is
    one of the most active volcanoes of the New Hebrides arc. A thick, almost
    exclusively pyroclastic sequence, initially dacitic, then basaltic,
    overlies lava flows of a pre-caldera shield volcano. The caldera was formed
    during a major Plinian eruption with dacitic pyroclastic flows about 1,900
    years ago. Post-caldera eruptions, primarily from Marum and Benbow cones,
    have partially filled the caldera floor and produced lava flows that ponded
    on the caldera floor or overflowed through gaps in the caldera rim.
    Post-caldera eruptions have also formed a series of scoria cones and maars
    along a fissure system oriented ENE-WSW. Eruptions have apparently occurred
    almost yearly during historical time from cones within the caldera or from
    flank vents. However, from 1850 to 1950, reporting was mostly limited to
    extra-caldera eruptions that would have affected local populations.

    Information Contacts: Jenifer E. Piatt, HQ Air Force Weather Agency
    Satellite Applications Branch (URL: Jenifer.Piatt@afwa.af.mil); Simon Carn,
    TOMS Volcanic Emissions Group, University of Maryland, 1000 Hilltop Circle,
    Baltimore, MD 21250, USA (Email: scarn@umbc.edu; URL:
    skye.gsfc.nasa.gov/); NASA Earth Observatory Natural Hazards web
    page (earthobservatory.nasa.gov/Natur...rds/).


    Manam
    Papua New Guinea
    4.10°S, 145.06°E; summit elev. 1,807 m
    All times are local (= UTC + 10 hours)

    Manam erupted several times during October to December 2004 and January
    2005. A strong eruption on 24 October 2004, preceded by a buildup in
    seismicity and a felt earthquake, was described in Bulletin v. 29, no. 10.
    This eruption generated pyroclastic flows, and its plume was imaged from
    space. The eruption sent ash and condensed water in the form of ice to a
    maximum height of ~15 km altitude. On 10-11 November 2004, a Strombolian
    eruption occurred; the ash column was estimated to have risen ~5-6 km above
    the crater. On 23-24 November 2004 Manam's main crater ejected glowing lava
    and discharged an ash cloud that rose ~10 km high. A lava flow was also
    reported to be heading for two villages on the island. Details and reports
    of eruptions in November and December 2004 were included in Bulletin v. 29,
    no.11.
    The eruption at Manam on the evening of 27 January 2005 (Bulletin v. 30,
    no. 2) was more severe than the previous ones during the current eruptive
    period. During 27-28 January 2005 there were 14 people injured and one
    person killed at Warisi village. The reports of the Rabaul Volcano
    Observatory (RVO) and the Darwin VAAC, and an analysis of the Manam
    eruption clouds by Andrew Tupper of the Darwin VAAC, were summarized in
    Bulletin v. 30, no. 2. In late January, five commercial flights were
    cancelled from Rabaul, East New Britain, delaying about 100 passengers.

    Documented occurrence of olfactory fatigue. A report received from Andrew
    Tupper discussed an encounter of an aircraft with an airborne gas plume
    that took place about 2300 UTC on 29 January (0800 on the 30th, East Timor
    time) reported to him by a pilot. The encounter took place at a
    considerable distance from Manam, and a map is helpful to visualize the
    region's geography (figure 3). The incident involved entry into a visibly
    anomalous, hazy-blue cloud that turned out to contain sulfurous odor
    (figure 4). Although Tupper and the pilot discussed other possibilities for
    the cloud's origin, Tupper came to the conclusion that the cloud was
    volcanic fog (vog) erupted from Manam.

    Figure 3. The airport at Dili, East Timor (Indonesia), located about 2,200
    km WSW of Manam.

    Key portions of the pilot's message conveyed to us by Tupper follow.

    "On descent into Dili, approaching 10,000 feet at 12 nautical miles [~3 km
    altitude and ~22 km from the airport] aircraft control levers were pulled
    back to flight idle just prior to entering a thin layer of smooth stratus
    cloud [figure 4].

    Figure 4. The hazy blue cloud that produced a sulfur smell in the cockpit
    of the plane approaching Dili. The photo was taken by the air crew (names
    not given).

    "Shortly after passing into the cloud, a strange smell was soon noticed in
    the cockpit; once the accusations of responsibility had passed, it quickly
    became apparent that the smell was not the result of a bodily function. The
    smell became very strong, with high sulfur content. As a precaution the
    Captain directed the First Officer to don his oxygen mask. The smell
    persisted but began to weaken on descent, and landing was accomplished
    without incident. After landing, First Officer removed the oxygen mask and
    noted the smell had remained. The captain had by this time become
    desensitized to the smell. Upon shutdown, unloading was halted, until such
    time as the cargo hold could be examined for a source of the smell. No
    smell remained."

    Tupper and the pilot discussed possible sources for the smell. The cloud
    displayed a distinct blue haze (Tupper commented that "it's difficult to
    tell from the attached photo whether the blue is all that
    out-of-the-ordinary, but obviously they thought it interesting enough to
    take a photo!"). The cloud sat on the hills and appeared to have fog-like
    characteristics. The pilot described the odor as sharper and more metallic
    than the smell of H2S (a description consistent with SO2, the odor of which
    is sometimes described as metallic or akin to a struck-match.

    What caused the sulfurous-smelling stratus cloud? The sulfur content may
    have come from either nearby volcanoes, none of which have been reported as
    active, or from industrial production (possibly Kupang). Due to a serious
    dengue outbreak in East Timor, it may have been the result of chemical
    mosquito control. Many chemical methods of mosquito control are based on
    sulfur products. Malathion is one such product; it contains mercaptan,
    which has a strong noxious odor. (Organic compounds with HS bound to carbon
    are called mercaptans or thiols and those of low molecular weight have
    strong smells. Small doses of mercaptan are often used to give natural gas
    a distinctive odor.) One possible way to explain the sulfurous gases was
    morning fog moving up the hills of Dili in response to anabatic
    (upslope-blowing) winds, which also carried residual insecticide.

    Tupper spoke to or emailed the pilot several more times to get the
    following other details. The aircraft was an Embraer E120, a 30 seat turbo
    prop, with 20-25 people on board. The cabin attendant also noticed the
    smell, but no passengers commented. Despite the speculation about chemicals
    above, this was the only trip on which the smells had been noticed by the
    pilot.

    According to Claire Witham, human perception of SO2 odor varies depending
    on the individual's sensitivity, but SO2 is generally perceived between
    0.3-1.4 ppm and is easily noticeable at 3 ppm. This is generally below the
    level where health effects (e.g. respiratory response) might be noted. In
    general an exposure limit of 1-5 ppm is the threshold for respiratory
    response in healthy individuals upon exercise or deep breathing, whilst at
    3-5 ppm the gas is easily noticeable and may cause a fall in lung function
    in persons at rest, and increased airway resistance. Asthmatic individuals
    may respond at much lower concentrations, and prolonged exposure to low
    concentrations carries increased risk for those with pre-existing heart and
    lung diseases. A more detailed review of gas hazards and guidelines has
    just gone online on the International Volcanic Health Hazard Network.

    Significant in this event is that the flight crew thought that the smell
    had dissipated. The First Officer, who was wearing an oxygen mask, remained
    able to detect that the smell persisted. This indicates that the others in
    the crew lost their ability recognize that the sulfurous odors remained, a
    well-know effect of sulfurous gases called olfactory fatigue ('bombarded
    nerve receptors'), a potentially confusing situation for pilots focused on
    escaping from a volcanic plume (Wunderman, 2004).

    Tupper conducted dispersion modeling of the 27 January 2005 Manam eruption
    (figure 5). The results suggested that the SO2 cloud from the volcano
    probably passed over East Timor on the night before the incident and at
    higher altitudes. This is supported to a limited extent by the preliminary
    ozone and SO2 monitoring results (figure 6), which suggest that the bulk of
    the cloud went N, but that part of the cloud traveled over the Banda Sea
    and passed over East Timor. The low level winds are highly unlikely to have
    carried the SO2 to East Timor, but there was significant storm activity on
    the night when the cloud would have passed over. Excluding other
    explanations on the grounds that the eruption / encounter timing are
    unlikely to be mere coincidence, the most likely explanation for the flight
    crew's experience is that some eruption products from Manam were rained out
    over East Timor on the night of 29 January 2005. If SO2 had been
    incorporated into ice particles, which then rained out, the particles would
    have melted and released SO2 at about the level of the encounter, where the
    temperature was a bit above freezing. According to this scenario, the plane
    then flew through the resultant vog/stratus the next morning.

    Figure 5. An ash dispersion model for the eruption cloud associated with
    the eruption of Manam on 27 January 2005. The model takes into account wind
    at various altitudes and other meteorological data, and predicts the
    movement of material injected in the atmosphere. The model used, NOAA
    hysplit, adopted the boundary condition that material was above the volcano
    between 10 and 24 km altitude starting at 1400 on 27 January. The results
    shown predict the dispersal for the interval 1200-1400 on 29 January. The
    model indicates that some material from Manam's 27 January eruption
    traveled WSW to where the aircraft-gas plume encounter took place. The
    model is a product of the NOAA Air Resources Lab with this particular run
    provided by Andrew Tupper.

    Figure 6. A satellite image of atmospheric SO2 burden from Manam made about
    12 hours after the 27-28 January 2005 eruption. The image resulted from the
    NASA Ozone Monitoring Instrument (OMI), which flew over the region on
    NASA's new Aura satellite. This image was produced from preliminary,
    uncalibrated data provided by the OMI. The OMI detected a large cloud of
    SO2 drifting W over the island of New Guinea. The gas is measured in Dobson
    Units (DU), a reflection of the number of molecules in a square centimeter
    of the atmosphere. Darker pixels cover the areas of highest concentration,
    while the lowest concentrations are represented by lighter ones (red and
    pink, respectively, on the colored electronic version of the Bulletin). If
    you were to compress all of the SO2 in a column of the atmosphere into a
    flat layer at standard temperature and pressure, one Dobson Unit would be
    0.01 mm (millimeters) thick and would contain 0.0285 grams of SO2 per m2.
    On January 28, the atmosphere over New Guinea contained up to 50 Dobson
    Units (red regions), or 1.425 grams of SO2 per square meter. NASA image and
    caption courtesy Simon Carn, Joint Center for Earth Systems Technology.

    Infrasound reports. The Comprehensive Nuclear Test Ban Treaty Organisation
    (CTBTO) is installing a world-wide network of 60 infrasound stations as
    part of the International Monitoring System (IMS) for detection of nuclear
    tests. The stations, some of which are already functioning, use
    microbarographs (acoustic pressure sensors) to detect very low-frequency
    (0.01-10 Hz) sound waves in the atmosphere produced by natural and
    anthropogenic events.

    The eruption at Manam on 27 January at ~1400 UTC was detected at several
    infrasound stations around the Pacific (table 1). In one case a signal was
    received at a distance exceeding 10,000 km. The sound of the explosion took
    more than ten hours to reach that most distant station, located in
    Washington state (USA). The difference in the calculated and measured
    signal azimuths is likely caused by high atmosphere winds, and is
    reasonable given the great distances that the signal traveled.

    Table 1. Arrival times and great circle paths for infrasound signal from
    Manam eruption on 27 January 2005 received at CTBTO infrasound stations.
    Courtesy of Robert North.

    CTBTO Infrasound Station Calculated great
    circle Measured Date Arrival
    path, station to
    volcano signal time
    Azimuth Distance azimuth
    (°E of N) (km) (°E of N)

    I07AU Warramunga, 35 2079 32 27
    Jan 2005 16:00 UTC
    Central Australia
    I22FR New
    Caledonia 311 3091 n/a n/a Not obs

    I05AU Tasmania, 356 4270 350 27
    Jan 2005 18:30 UTC
    Australia
    I55US Windless Bight, 336 8303 335 27
    Jan 2005 22:07 UTC
    Antarctica
    I53US Fairbanks, 247 9358 252 27
    Jan 2005 23:12 UTC
    Alaska
    I56US Newport, 273 10920 276 28
    Jan 2005 00:34 UTC
    Washington

    Subsequent RVO observations. Although it remained active, Manam calmed
    considerably during February-May 2005. During the first two weeks of
    February 2005, emissions from Manam continued. On 15 February 2005, the
    alert level was reduced from 3 to 2. Mild eruptive activity was observed
    from Manam's Southern crater during the third week of February.
    Weak-to-moderate ash explosions rose a few hundred meters above the crater
    and drifted E and SE, depositing fine ash in areas downwind. Throughout
    February, seismicity was at low levels, with small low-frequency
    earthquakes occurring and no volcanic tremor. Throughout March,
    weak-to-moderate emissions from both the Main and Southern craters
    continued to produce occasional ash clouds during most days. On 15 March, a
    thin plume from Manam was visible on satellite imagery. On 24 March,
    emissions from Main crater rose to ~1 km above the summit. On 28 March, a
    moderate explosion produced an ash plume to a height of ~1.2 km above the
    summit. Ash plumes drifted N, depositing ash on the island. Seismic
    activity fluctuated between low and moderate, with low-frequency
    earthquakes recorded.

    During April and May 2005, mild eruptive activity continued at the volcano.
    Manam remained at alert level 2 from February 2005 through at least late
    May. A thin plume extending 55 km NW on 4 May was seen on satellite imagery
    by the Darwin VAAC. The ash cloud remained below 3 km altitude.

    Background. The 10-km-wide island of Manam, lying 13 km off the northern
    coast of mainland Papua New Guinea, is one of the country's most active
    volcanoes. Four large radial valleys extend from the unvegetated summit of
    the conical 1,807-m-high basaltic-andesitic stratovolcano to its lower
    flanks. These "avalanche valleys", regularly spaced 90 degrees apart,
    channel lava flows and pyroclastic avalanches that have sometimes reached
    the coast. Five small satellitic centers are located near the island's
    shoreline on the northern, southern and western sides. Two summit craters
    are present; both are active, although most historical eruptions have
    originated from the southern crater, concentrating eruptive products during
    the past century into the SE avalanche valley. Frequent historical
    eruptions have been recorded at Manam since 1616. A major eruption in 1919
    produced pyroclastic flows that reached the coast, and in 1957-58
    pyroclastic flows descended all four radial valleys. Lava flows reached the
    sea in 1946-47 and 1958.

    Reference: Wunderman, R., 2004, Sulfurous odors: A signal of entry into an
    ash plume-perhaps less reliable for escape, Second International Conference
    on Volcanic Ash and Aviation Safety (Alexandria, Virginia, USA), 21-24 June
    2004 (Plenary Session 1: Encounters, Damage, and Socioeconomic
    Consequences, poster P 1.2, Socioeconomic consequences)
    (www.ofcm.gov/ICVAAS/Proc...edings.htm).

    Information Contacts: Andrew Tupper, Darwin Volcanic Ash Advisory Centre,
    Australian Bureau of Meteorology (URL: www.bom.gov.au/info/vaac);
    Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea;
    David Innes, Flight Safety Office, Air Niugini, PO Box 7186, Boroko, Port
    Moresby, National Capital District, Papua New Guinea (Email:
    dinnes@airniugini.com.pg or deejayinnes@yahoo.com, URL:
    www.airniugini.com.pg/); International Volcanic Health Hazard
    Network (URL: www.ivhhn.org/); Simon Carn, TOMS Volcanic Emissions
    Group, Univ. of Maryland, 1000 Hilltop Circle, Baltimore, MD 21250, USA
    (Email: scarn@umbc.edu; URL: skye.gsfc.nasa.gov/); Claire Witham,
    Meteorology Office, FitzRoy Road, Exeter, EX1 3PB, UK (Email:
    claire.witham@metoffice.gov.uk); Robert North, SAIC Monitoring Systems
    Division, 1953 Gallows Rd., Vienna, VA 22182, USA
    (Email:robert.g.north@saic.com); NOAA Air Resources Lab (ARL), Room 3316,
    1315 East-West Highway, Silver Spring, MD 20910, USA (URL:
    www.arl.noaa.gov/ready/).


    Langila
    Papua New Guinea
    5.525°S, 148.42°E; summit elev. 1,330 m
    All times are local (= UTC + 10 hours)

    Langila was last reported on in Bulletin v. 29, no. 6, as part of a MODIS
    data summary, although the last prominent event there was on 18 January
    2003, when a large explosion produced a thick dark ash column that
    penetrated the weather clouds over the summit area (Bulletin v. 28, no. 3).

    A plume from Langila was visible on satellite imagery on 17 December 2004
    according to the Darwin VAAC. The plume reached an unknown height and
    extended NW.

    Between 28 April 2005 and 4 May 2005 the Rabaul Volcano Observatory (RVO)
    received reports of activity at Langila characterized by forceful emissions
    of thick white to gray ash-laden clouds rising ~700-800 m above the summit
    crater. Occasional continuous rumbling and explosive noises were heard and
    incandescence was visible at night. During early May, incandescent lava
    fragments were ejected. Activity increased at about 1300 on 4 May 2005,
    when white-to-gray ash emissions changed to dark ash clouds. Explosions
    became frequent, with incandescent lava fragments ejected again, and very
    bright glow was visible during the night. Around 1200 on 5 May 2005 the
    color of the ash emissions changed from dark gray to white-to-gray. A lava
    flow was produced but no further detail is available. Based on information
    from RVO, the Darwin VAAC reported that ash emissions from Langila rose to
    ~2.1 km altitude on 3 May. A very small plume and a hot spot were visible
    on satellite imagery. Ash clouds from the eruption were blown generally NW
    towards Kilenge ~100 km away, where light to moderate ashfall was reported.

    According to the Darwin VAAC, low-level ash plumes emitted from Langila
    were visible on satellite imagery during 8-13 June 2005. RVO reported to
    the Darwin VAAC that moderate eruptive activity was expected to continue.

    The International Federation of Red Cross and Red Crescent Societies (IFRC)
    reported that eruptive activity occurred at Langila on 2 June with more ash
    than normal being emitted from the volcano. Prevailing winds carried most
    of the initial ashfall to the sea, but lower-level winds redirected the ash
    back onto the island. About 10,000 people live near the volcano, and there
    were reports of increased cases of respiratory problems and eye irritation.
    During an aerial inspection of the area on 6 June 2005, IFRC determined
    that ~3,490 people had been affected by the eruption, mainly in the
    villages of Aitavala, Masele, Kilenge, Ongaea, Potne, and Sumel, but also
    to a lesser extent in Vem, Galegale, Tauale, and Laut. Ashfall damaged
    small food gardens and contaminated some water sources. The provincial
    government encouraged voluntary evacuation of affected areas.

    During 16-17 June 2005, ash plumes from Langila were visible on satellite
    imagery (figure 7). The heights of the plumes were not reported.

    Figure 7. On 21 June 2005 the Moderate Resolution Imaging Spectroradiometer
    (MODIS), flying on NASA's Aqua satellite, captured this image of Langila,
    Ulawun, and Rabaul. At the time MODIS captured this image, Langila showed
    the biggest plume of volcanic ash, followed by Ulawun. In all cases, winds
    pushed the ash clouds NW over the ocean. NASA image courtesy Jesse Allen,
    based on data from the MODIS Rapid Response Team at NASA.

    Background. Langila, one of the most active volcanoes of New Britain,
    consists of a group of four small overlapping composite basaltic-andesitic
    cones on the lower eastern flank of the extinct Talawe volcano. Talawe is
    the highest volcano in the Cape Gloucester area of NW New Britain. A
    rectangular, 2.5-km-long crater is breached widely to the SE; Langila
    volcano was constructed NE of the breached crater of Talawe. An extensive
    lava field reaches the coast on the N and NE sides of Langila. Frequent
    mild-to-moderate explosive eruptions, sometimes accompanied by lava flows,
    have been recorded since the 19th century from three active craters at the
    summit of Langila. The youngest and smallest crater (no. 3 crater) was
    formed in 1960 and has a diameter of 150 m.

    Information Contacts: Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of
    Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina,
    Northern Territory 0811, Australia (URL: www.bom.gov.au/info/vaac/);
    Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea;
    International Federation of Red Cross And Red Crescent Societies (IFRC),
    Langila Volcano Information Bulletin No. 1 (URL: www.reliefweb.int/).


    Egon
    Lesser Sunda Islands, Indonesia
    8.67°S, 122.45°E; summit elev. 1,703 m
    All times are local (= UTC + 8 hours)

    Table 2 below tabulates the seismic activity by date of the volcano prior
    to and subsequent to its eruption on 6 February 2005, but little was
    reported concerning that event. The volcano erupted again on 7 February.
    That eruption was accompanied by a strong smell of SO2 or H2S in the
    villages of Hebing and Hale and apparently rendered a villager unconscious.

    Table 2. A summary of counts for different earthquake types (type B
    volcanic, type A volcanic, emission, low frequency, and tectonic), tremor,
    amplitude, and Alert Level at Egon volcano. Unreported data indicated by
    "--". Courtesy of the Directorate of Volcanology and Geological Hazard
    Mitigation (DVGHM) DVGHM.

    Date Volcanic Volcanic Emission Low Tectonic
    Tremor Alert
    B A Frequency
    amplitude Level

    05 Jan
    2005 16 1 7 6 8 2-3
    mm 3
    06 Jan
    2005 48 -- 3 -- 7 1-2
    mm 3
    Week of 24
    Jan 48 1 1 53 18 -- 3
    Week of 01
    Feb 152 3 -- 109 76 -- --
    14 Feb
    2005 32 17 -- -- 5 30
    mm 4
    25-27 Feb
    2005 61 4 24 2 19 1 mm 4

    On 8 February 2005 a fissure about 1 km long appeared along the southern
    slope. Vegetation along the fissure's margins had died, indicating that a
    gas blow out had occurred there. On 14 February 2005 at 1830 another
    explosion occurred. It was accompanied by significant seismic activity (see
    table 2). This latest eruption ejected ash and glowing material as high as
    50 m above the summit. Volcanic earthquakes were frequent.

    Distances increased for electronic distance measurements (EDM) during
    April, July, and October 2004 and during February 2005 (the last four
    measurements). During 25-27 February 2005 ash plumes rose to 50 m high.
    Volcano status remained at alert level 4 (the highest hazard status).

    Background. Gunung Egon volcano sits astride the narrow waist of eastern
    Flores Island. The barren, sparsely vegetated summit region has a
    350-m-wide, 200-m-deep crater that sometimes contains a lake. Other small
    crater lakes occur on the flanks of the 1,703-m-high volcano. A lava dome
    forms the southern 1,671-m-high summit. Solfataric activity occurs on the
    crater wall and rim and on the upper southern flank. Reports of historical
    eruptive activity prior to explosive eruptions in 2004 were inconclusive. A
    column of "smoke" was often observed above the summit during 1888-1891 and
    in 1892. Strong "smoke" emission in 1907 reported by Sapper (1917) was
    considered by the Catalog of Active Volcanoes of the World (Neumann van
    Padang, 1951) to be an historical eruption, but Kemmerling (1929) noted
    that this was likely confused with an eruption on the same date and time
    from Lewotobi Lakilaki volcano.

    Information Contacts: Dali Ahmad, Hetty Triastuty, Nia Haerani, and Sri
    Kisyati, Directorate of Volcanology and Geological Hazard Mitigation
    (DVGHM), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email:
    dali@vsi.esdm.go.id; URL: www.vsi.esdm.go.id/).

    Karangetang [Api Siau]
    Siau Island, Indonesia
    2.47°N, 125.29°E; summit elev. 1,784 m
    All times are local (= UTC + 8 hours)

    Ongoing seismicity continued at Karangetang during January-February 2005.
    Lava avalanches were noted on 3 January and during the week of 17-23
    January. The volcano was last discussed in a report on thermal alerts and a
    pilot's report of an ash plume to 7.5 km altitude (Bulletin v 29, no.3,
    which updated through May 2004). Table 3 presents a summary of the reported
    seismic and other data during January and February 2005.

    Table 3. A summary of observations made at Karangatang during 3
    January-February 2005. Courtesy of DVGHM.

    Date Volcanic Volcanic Multi- Emission Tremor Lava
    Tectonic Alert
    A B phase
    Avalanches Level

    03 Jan 3 10 2 2 0.5-3
    mm 5 8 3
    04 Jan 9 4 -- -- 0.5-1
    mm -- 7 3
    05
    Jan 2 11 1 -- -- --
    3 3
    17-23
    Jan 61 125 6 -- -- 36
    36 3

    Background. Karangetang (Api Siau) volcano lies at the northern end of the
    island of Siau, N of Sulawesi. The 1784-m-high stratovolcano contains five
    summit craters along a N-S line. Karangetang is one of Indonesia's most
    active volcanoes, with more than 40 eruptions recorded since 1675 and many
    additional small eruptions that were not documented in the historical
    record (Catalog of Active Volcanoes of the World: Neumann van Padang,
    1951). Twentieth-century eruptions have included frequent explosive
    activity sometimes accompanied by pyroclastic flows and lahars. Lava dome
    growth has occurred in the summit craters; collapse of lava flow fronts has
    also produced pyroclastic flows.

    Information Contacts: Dali Ahmad, Hetty Triastuty, Nia Haerani, and Sri
    Kisyati, Directorate of Volcanology and Geological Hazard Mitigation
    (DVGHM), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email:
    dali@vsi.esdm.go.id; URL: www.vsi.esdm.go.id/).


    Barren Island
    Andaman Islands, Indian Ocean
    12.278°N, 93.858°E; summit elev. 354 m
    All times are local (= UTC + 5 ½ hours)

    Members of the Indian Coast Guard observed a new eruption on the morning of
    28 May 2005. An ash plume originated from a vent on the W side of the
    summit of the central cone; fresh black lava flows did not reach the sea
    (figure 8). The eruption continued through at least 6 June. Fresh lava
    emissions had been noted by Indian Coast Guard personnel who patrol the
    area regularly. A large amount of steam was emitted due to heavy rainfall
    onto the hot lava surfaces. Heavy monsoon rains prevented access to the
    island. However, the Geological Survey of India (GSI) was planning a
    monitoring program and field expedition to the island.

    Figure 8. Photograph of Barren Island erupting on 28 May 2005 taken from a
    helicopter. The black lava in the foreground is of 1994-95 eruption. A lava
    flow that did not reach the sea issues from a steaming flank vent. View is
    towards the ESE. Courtesy of the Indian Coast Guard.

    Dornadula Chandrasekharam (Indian Institute of Technology) noted on 6 July
    that by that date the eruption had ceased, with only steam emissions
    continuing after three weeks of heavy monsoon rains. The Indian Coast Guard
    also confirmed to Chandrasekharam that the eruption was first noticed on 28
    May, contrary to some press reports indicating that activity was seen on
    the 27th. Patrol helicopters saw no activity on 25 and 26 May, and did not
    observe the island on the 27th.

    Press reports. A report in the 31 May edition of The Hindu stated that
    defense forces witnessed intermittent billowing smoke and "flame" from the
    volcano. The same article referenced a Press Trust of India (PTI) report
    that military forces that landed on the island "experienced a hot breeze
    and found themselves stepping on fresh lava" where earlier patrol teams had
    been able to reach the crater. Another article from The Hindu reported that
    on 2 June teams of the Indian Coast Guard vessel CG Sagar landed on the
    island in an inflatable raft while a helicopter hovered overhead. The
    report described eruptive activity consisting of lava and "fireballs" from
    the crater every few seconds. The purpose of the expedition was to "collect
    samples of the lava flowing into the rough sea" that would be given to
    scientists. Coast Guard members and various other government officials made
    an aerial survey of the island on 3 June according to a PTI report
    published in The Hindu the next day. The Lt. Governor of Andaman, Ram
    Kapse, saw "smoke and lava rising from the crater." Coast Guard sources
    stated that the volume of "smoke" had increased and lava was still flowing
    out of the crater.

    A report in The Daily Telegrams on 17 February 2005 quoted K.N. Mathur,
    Director General of the GSI, regarding a scientific visit to Barren Island
    on 16 February. At that time, Mathur noted, the team observed "no serious
    volcanic activities on the island." A similar report in the 18 February
    edition of the Trinity Mirror carried a quote from Mathur that "There is no
    activity in the crater and it remained as it was found during GSI's last
    visit in 2003." These media reports were reproduced on the GSI website.

    Background. Barren Island, a possession of India in the Andaman Sea about
    135 km NE of Port Blair in the Andaman Islands, is the only historically
    active volcano along the N-S-trending volcanic arc extending between
    Sumatra and Burma (Myanmar). The 354-m-high island is the emergent summit
    of a volcano that rises from a depth of about 2,250 m. The small,
    uninhabited 3-km-wide island contains a roughly 2-km-wide caldera with
    walls 250-350 m high. The caldera, which is open to the sea on the W, was
    created during a major explosive eruption in the late Pleistocene that
    produced pyroclastic-flow and -surge deposits. The morphology of a fresh
    pyroclastic cone that was constructed in the center of the caldera has
    varied during the course of historical eruptions. Lava flows fill much of
    the caldera floor and have reached the sea along the western coast during
    eruptions in the 19th century and more recently in 1991 and 1995.

    Information Contacts: Dornadula Chandrasekharam, Department of Earth
    Sciences, Centre of Studies in Resources Engineering, Indian Institute of
    Technology, Bombay 400076, India (Email: dchandra@geos.iitb.ac.in);
    Geological Survey of India, 27 Jawaharlal Nehru road, Kolkata 700016, India
    (URL: www.gsi.gov.in/barren.htm); The Daily Telegrams, India (URL:
    www.and.nic.in/telegrame.htm); Trinity Mirror, Chennai, India; The
    Hindu, 859 and 860 Anna Salai, Chennai 600002, Tamil Nadu, India (URL:
    www.hinduonnet.com/); Press Trust of India, PTI Building, 4,
    Parliament Street, New Delhi 110001, India (URL: www.ptinews.com/);
    Indian Coast Guard, National Stadium Complex, New Delhi 110 001, India
    (URL: indiancoastguard.nic.in/indian....HTML).


    Long Valley
    California, USA
    37.70°N, 118.87°W; summit elev. 3,390 m
    All times are local (= UTC - 8 hours)

    The relative quiescence in Long Valley caldera that began in early 1999
    persisted through 2004 according to the U.S. Geological Survey's weekly
    reports and the 2004 annual summary of the Long Valley Observatory. Those
    manuscripts provide the basis for this synopsis. Seismicity in the
    adjacent Sierra Nevada block S of the caldera gradually died away over the
    same period, although background levels remained somewhat higher than
    within the caldera.

    The resurgent dome continued to undergo minor fluctuations in deformation
    as reflected in changes in the lengths of baselines onto the dome. Over the
    past 6 years, the center of the resurgent dome has sustained the roughly
    75-cm uplift that accumulated during the recurring unrest from 1979 through
    1999.

    Seismicity within both the caldera and the Sierra Nevada block to the S
    remained low through 2004. The two most notable earthquake sequences within
    the caldera were a minor swarm at the end of January and the first few days
    of February in the S moat, and a M 3.0 earthquake on 20 September located
    at the S margin of the caldera just N of Convict Lake. The latter was the
    first earthquake greater than M 3.0 within the caldera since the cluster of
    earthquakes on 4 November 2002, events centered beneath the S moat just S
    of the Highway 395-203 junction. The swarm in early February 2004 was
    located in the same general area of the S moat, but the epicenters fell
    along a SW trend in contrast to the WNW trend shown by most earthquake
    sequences in that area.

    Seismicity within the adjacent Sierra Nevada block continued to be somewhat
    elevated compared to that in the caldera through 2004. The Sierra Nevada
    activity included about seven earthquakes over M 3, the largest of which
    was an M 3.7 earthquake on 12 January 2004 located 2 km E of Red Slate
    Mountain (19 km S of the caldera and 15 km WSW of Tom's Place). Most of the
    activity remained concentrated in the NNE-trending aftershock zone
    associated with the three earthquakes over M 5 during June and July 1998
    and May 1999.

    The most noteworthy seismic activity in the general vicinity of Long Valley
    caldera during 2004 was the prolonged earthquake swarm in the Adobe Hills
    centered roughly 20 km E of Mono Lake and 20 km NNE of Long Valley caldera
    (figure 9). Its onset was marked by a M 2.3 earthquake at 0002 on 18
    September, followed by M 3.2 and 4.1 earthquakes at 0007 and 0008,
    respectively. Activity intensified through mid-afternoon of 18 September,
    with M 5.5 and M 5.4 earthquakes at 1602 and 1643, respectively. These
    produced widely felt shaking in the area from Bridgeport to Bishop.
    Seismicity declined gradually through the remainder of the year and into
    early 2005. By the end of December 2004, this Adobe Hill swarm had produced
    well over 1,000 detectable earthquakes including ~48 over M 3 and 6 equal
    or over M 4.

    Figure 9. All earthquake epicenters detected in the Long Valley region for
    2004. Courtesy of U.S. Geological Survey, Long Valley Observatory (2005).

    The mid-crustal long-period (LP) volcanic earthquakes, which began beneath
    the SW flank of Mammoth Mountain during the 1989 Mammoth Mountain
    earthquake swarm, continued through 2004 but at a much reduced rate
    compared with the peak in LP activity from early 1997 through mid-1998.

    In early 2005 seismicity was generally minor (up to M 2.5) in and around
    the caldera. An M 4.2 earthquake occurred S of Long Valley caldera on 13
    March 2005 at 1409. The event, which produced light shaking in Mammoth
    Lakes and Bishop was located in the Sierra Nevada ~12 miles SW of Toms
    Place near Grinnell Lake. It was followed by a series of 18 aftershocks,
    the largest which were M 2.8 and M 2.3. The last earthquake of similar
    magnitude in this area occurred in 1999 on 17 May. In addition to the M 4.2
    main shock/aftershock sequence, two other significant earthquakes occurred
    in the Adobe Hills area E of Mono Lake, and a third occurred on 13 March in
    the Sierra Nevada S of the caldera, near Mount Baldwin. All three had
    magnitudes under M 2.0. From that time to mid-June 2005, seismicity was
    generally in the range of M 1-2, with a very few occurring to M 3.

    Carbon dioxide (CO2) concentrations measured in the Horseshoe Lake
    tree-kill area on the S flank of Mammoth Mountain showed no significant
    changes for 2004 with respect to the past several years. A survey of
    scattered areas of vegetation die-off and diffuse CO2 flux on the resurgent
    dome completed in 2004 indicated anomalous CO2 emissions from the kill
    areas were ~9 metric tons/day (compared with ~300 tons/day from Mammoth
    Mountain). The d^13C-CO2 values of the diffuse emissions were similar to
    values previously reported for CO2 from hot springs and thermal wells
    around Long Valley, indicating a common source. The areas of elevated CO2
    flux tend to be associated with locally elevated soil temperatures. Some of
    the older areas near the Casa Diablo power plant are likely related to
    geothermal power production, but development of new areas may reflect a
    delayed response of the hydrothermal system to the 1997 unrest episode
    (including an additional 10-cm uplift of the resurgent dome accompanied by
    intense earthquake swarm activity in the S moat).

    Thermal spring discharge in Hot Creek Gorge, which had dropped by about 20%
    in the last half of 2003, followed by a recovery beginning in January 2004,
    reached normal discharge values by June 2004.Fluid levels in key monitoring
    wells continued to decline, with some wells reaching their lowest values
    since records began in 1985.

    Background. The large 17 x 32 km Long Valley caldera E of the central
    Sierra Nevada Range formed as a result of the voluminous Bishop Tuff
    eruption about 730,000 years ago. Resurgent doming in the central part of
    the caldera occurred shortly afterwards, followed by rhyolitic eruptions
    from the caldera moat and the eruption of rhyodacite from outer ring
    fracture vents, ending about 50,000 years ago. During early resurgent
    doming the caldera was filled with a large lake that left strandlines on
    the caldera walls and the resurgent dome island; the lake eventually
    drained through the Owens River Gorge. The caldera remains thermally
    active, with many hot springs and fumaroles, and has had significant
    deformation, seismicity, and other unrest in recent years. The
    late-Pleistocene to Holocene Inyo Craters cut the NW rim of the caldera,
    but are chemically and tectonically distinct from the Long Valley system.

    Reference: U.S. Geological Survey-Long Valley Observatory, 2005, Long
    Valley Observatory Quarterly Report, October-December 2004 and Annual
    Summary for 2004 (URL: lvo.wr.usgs.gov/).

    Information Contacts: Long Valley Observatory, U.S. Geological Survey, 345
    Middlefield Rd., MS 977, Menlo Park, CA 94025, USA (URL:
    lvo.wr.usgs.gov/).


    Reventador
    Ecuador
    0.078°S, 77.656°W; summit elev. 3,562 m
    All times are local (= UTC - 5 hours)

    Crisis escalates. Instituto Geofisico (IG) members noted that eruptions at
    Reventador in Ecuador's eastern cordillera continued into at least early
    July 2005. Observers documented thick blocky lava flows, occasional
    Vulcanian explosions, new fumarolic activity on the N flank of the cone,
    and venting of vapor, gases, and fine ash. This followed a spate of
    increased seismicity during April to early June 2005. Lava flows had
    extended 4 km from the summit vent toward the SE, in the direction of the
    main highway across this region, a route that links the important oilfields
    in the Amazon basin with Quito, the capital. The lava flows were
    sequentially numbered (Lava #3, #4, etc.).

    Lava #3, a flow that began in November 2004 (Bulletin v. 29, no. 11),
    advanced slowly and ceased movement by early January 2005. Following
    relatively low seismic activity in late 2004 and early 2005, the IG
    monitoring network began to register bands of harmonic tremor starting 1
    April (figure 10). Through 8 April 2005, instruments recorded 45 tremor
    episodes, each lasting 10 to 60 minutes. Dominant frequency peaks were
    between 1 and 1.5 Hz. Given that strong incandescence was observed by a
    guard of PetroEcuador from 14 km away, the tremor was interpreted to signal
    the rise of magma into the upper part of the cone through an open conduit.

    Lava #4 erupted coincident with this strong tremor and was the most
    important surface manifestation. It was first observed in an overflight on
    12 April, escaping from a summit crater conduit that had formed a
    carapace. It was seen flowing down the SW crater notch onto the cone's
    flanks and then onto the SW and SE caldera floor. The flow partially
    covered Lava #3 (figure 11), resulting in layers of recent lava in some
    places reaching more than 50 m thick. This emplacement was observed during
    several days of work on the seismic instrumentation and sampling within the
    caldera carried out by IG personnel during 19-22 April. During the same
    overflights, a new fumarole field was observed on the lower S flank of the
    cone, a spot very close to the upper Reventador River, in the same place
    where thermal anomalies were observed on 11 March 2005.

    Figure 10. Seismic events registered at Reventador since August 2004.
    Courtesy of IG.

    Figure 11. Location of lava flows related to eruptive activity within the
    Reventador caldera since 2002. Photo taken looking at the SE flank on 6
    May 2005 by P. Ramon. Provided courtesy of IG.

    Starting on 15 May there was an important increase in the intensity of
    harmonic tremor, often preceded by low frequency (< 1 Hz) long-period
    events, a conspicuous aspect of behavior that was absent in April. Many of
    the long-period events, particularly those occurring during 17-21 May, were
    of such magnitude that they registered at seismic stations on other
    volcanoes (e.g., Cerro Negro and Guagua Pichincha) more than 100 km distant.
    After this elevated activity in mid May, there was a decrease in the number
    of events, dropping to an average of 88 per day. During this period Lava
    #4 continued to flow, moving at the rate of about 20 m/day, advancing
    particularly strongly along the caldera's S wall in a stream channel (Rio
    Marker) cut through the 2002 pyroclastic deposits. Lava reached 25 meters
    thick when seen during a 22-23 May visit, during which time strong roars
    and the sounds of 'many jet planes' blared from the vent. These sounds
    indicated a strong gas flux, although little vapor was observed. At this
    time, there was an absence of both explosions and incandescence in the
    summit crater.

    An overflight on 25 May confirmed the emergence of a new flow (Lava
    #5). It followed the same route as #4, but was comprised of three
    principal lobes. The middle lobe, which represented the most conspicuous
    and largest volume, advanced down the Rio Marker's channel (figure 12).

    Figure 12. Lavas 4 and 5 flowing down the Marker's stream channel along the
    SE margin of Reventador's caldera. Photo taken on 17 June 2005 by P.
    Ramon. Provided courtesy of IG.

    Reventador's activity in June 2005 began with an important swarm of
    volcano-tectonic and hybrid seismic events-starting on the 2nd and
    continuing through the 3rd. Of particular note, tremor continued for more
    than 10 hours, and provided background to the discrete volcano-tectonic and
    hybrid events Hybrid events had not been registered since November
    2004. Following these important swarms, instruments registered strong,
    full-amplitude bands of spasmodic tremor, comprised to some extent by
    packages of long-period events lasting for hours to days on end.

    During these early days of June, there was an intensification of
    incandescence in the crater and later, the emission of gases and slight
    ash. On 8 June, a 100 km long vapor/ash column extended from the volcano
    into the S part of Quito at ~7 km altitude and caused a very slight
    powdering of ash, which was brought down by a gentle rain and left cars
    dappled with circular spots.

    A trip by IG volcanologists into the caldera on 11-12 June disclosed strong
    Strombolian fountaining in the summit crater. Lava #5 continued to flow
    atop the stalled Lava #4. Measurements of SO2 flux with a mini-DOAS
    (differential optical absorption spectroscopy) resulted in an estimate of
    ~2,500 metric tons/day.

    Three other seismic stations were installed around the caldera with the
    helicopter help of the petroleum company OCP during 16-19 June. One
    broad-band seismograph and infrasound system was also installed, thanks to
    collaboration with Jeff Johnson of the University of New Hampshire. During
    this period no Strombolian activity was observed, but Vulcanian explosions
    (figure 13) occurred with little warning. A 24-hour period during 18-19
    June included at least seven discrete explosions, producing strong
    infrasound and seismic responses. Many of these explosions discharged
    columns that rose 2-3 km above the summit (and some, up to as high as ~6 km
    above the summit) and were clearly heard within the caldera. Large
    incandescent blocks could be seen thrown several hundreds of meters into
    the air, falling on the cone's upper slopes. Ash content in the columns
    was moderate. Explosions were discrete and often terminated within 4
    minutes. Thermal alerts were identified by the Hawaii Institute of
    Geophysics and Planetology (HIGP). Observations on 30 June and 1 July
    noted recent lava flows in the upper Marker river valley (figure 14).

    Figure 13. One of Reventador's discrete Vulcanian explosions observed
    during a 19 June 2005 helicopter flight. The view is from the E of
    Reventador caldera looking toward the W. Photo taken on by P. Ramon;
    provided courtesy of IG.

    Figure 14. A photo of Reventador's Lava #4 flow front (which had reddish
    hues) overtopped by Lava #5 (more nearly white). The shot was taken in the
    Rio Marker at 1100 on 30 June 2005. By 1 July, Lava #5 had still not
    advanced beyond the terminus of Lava #4. Photo by P. Ramon, provided
    courtesy of IG.

    The 4-6 discrete explosive degassing events/day observed in June led the IG
    authors to surmise that there were a series of temporary plugs in the upper
    part of the conduit. This behavior was thought to reflect magma becoming
    more crystal rich.

    As of 6 July, harmonic tremor, occasional explosions, and long-period and
    volcano-tectonic signals all continued to register at Reventador on the
    IG's telemetered monitoring network. Strong Strombolian fountaining was
    observed from distances of 6.5 and 14 km during the evening and one of the
    lobes of Lava #5 was advancing down the caldera wall (following the Rio
    Marker), but abruptly slowed to perhaps only ~20 m/day. In comparison, this
    flow-front velocity had earlier attained ~70 m/day (during 19-23 June) and
    ~50 m/day (during 23-30 June). The diminished rate of advance and
    continuing high-amplitude tremor suggested that perhaps a new lava flow
    (Lava #6) had broken out high on the flanks, a conjecture yet to be
    confirmed by press time. Lava #5 was still 1.2 km from the steep incline, a
    point where it could begin rapid descent to the alluvial fan where the
    highway and petroleum pipeline are located.

    Background. Reventador is the most frequently active of a chain of
    Ecuadorian volcanoes in the Cordillera Real, well E of the principal
    volcanic axis. The forested dominantly andesitic stratovolcano rises to
    3,562 m above the remote jungles of the western Amazon basin. A 4-km-wide
    caldera widely breached to the E was formed by edifice collapse and is
    partially filled by a young, unvegetated stratovolcano that rises about
    1,300 m above the caldera floor to a height above the caldera rim.
    Reventador has been the source of numerous lava flows as well as explosive
    eruptions that were visible from Quito in historical time. Frequent lahars
    in this region of heavy rainfall have constructed a debris plain on the
    eastern floor of the caldera. The largest historical eruption at Reventador
    took place in 2002, producing a 17-km-high eruption column, pyroclastic
    flows that traveled up to 8 km, and lava flows from summit and flank vents.

    Information Contacts: Patricia Mothes, Patricio Ramon, Pete Hall, Daniel
    Andrade, and Liliana Troncoso, Geophysical Institute (IG), Escuela
    Politecnica Nacional, Apartado 17-01-2759, Quito, Ecuador (URL:
    www.igepn.edu.ec/; Email: pmothes@igepn.edu.ec; pramon@igepn.edu.ec;
    mhall@igepn.edu.ec; dandrade@igepn.edu.ec; ltroncoso@igepn.edu.ec); Jeffrey
    B. Johnson, Dept. of Earth Sciences, James Hall University of New
    Hampshire, Durham, NH 03824, USA (Email: jeff.johnson@unh.edu).


    Lascar
    northern Chile
    23.37°S, 67.73°W; summit elev. 5,592 m
    All times are local (= UTC - 4 hours)

    The 4 May 2005 early morning eruption of Lascar was described in Bulletin
    v. 30, no. 4. Note that the time conversion in that issue was in error by 1
    hour. The following information is based on a report prepared for Bulletin
    staff by Jose Viramonte of the Universidad Nacional de Salta, and Lizzette
    Rodriguez of Michigan Technological University.

    Viramonte and Rodriguez estimated that the 4 May 2005 eruption column rose
    to a height of ~10-11 km, based on numerical models of temperature and wind
    measurements from the Servicio Metereologico Nacional, Argentina at
    different altitudes at the time of the eruption. The column traveled
    rapidly to the SE under the influence of the strong tropospheric winds with
    predominant direction from the NW to the SE.

    Residents of the towns of Talabre (located 15 km W of the volcano) and Jama
    (located 60 km ENE of the volcano) did not report earthquakes or
    explosions. The Instituto GEONORTE of the Universidad Nacional de Salta
    reported very fine ashfall at 0545 in the city of Salta, located ~285 km
    SSE of the volcano. Ash sample collection, carried out by GEONORTE
    personnel for 2.5 hours, measured a rate of 0.4 g/ (m²h). Grain size
    analyses of the ash showed a strong mode at diameters of 4-8 phi
    (0.062-0.003 mm) (figure 15); the ash was composed predominantly of
    andesitic lithic fragments and broken crystals of two pyroxenes (hyperstene
    and augite) and plagioclase, with very scarce glass shards.

    Figure 15. Histogram of the grain size of ash deposited at the city of
    Salta by the 4 May 2005 Lascar eruption. Courtesy of Jose Viramonte and
    Lizzette Rodriguez.

    The Buenos Aires VAAC and the Comision Nacional de Actividades Espaciales
    (CONAE) processed different bands from MODIS data: b29-b32 for SO2, b31-b32
    for ash, and b30-b32 for SO4. The first two band combinations showed the
    Lascar plume in coincidence with the b5-b4 band combination from NOAA-17
    (figure 16).

    Figure 16. NOAA-17 image of a SE-directed plume from Lascar at 1440 UTC
    (1040 local time), obtained with the difference of channels 4 and 5 from
    the AVHRR sensor. The plume can be better identified withing the ellipse on
    higher resolution reproductions. Courtesy of Jose Viramonte and Lizzette
    Rodriguez.

    The grain size and shape of the ash, its composition, and the
    interpretation of the satellite data, suggest that Lascar volcano had a
    short phreato-vulcanian eruption.

    On May 25, Felipe Aguilera of the Universidad Catolica del Norte,
    Antofagasta, Chile, climbed up to the crater of Lascar volcano (figure 17).
    He reported three new strong fumaroles a few meters from the S border of
    the crater, and sampled the sulfur sublimates (figure 18). No new bombs or
    blocks were seen around the crater area.
    Figure 17. View of Lascar's NE crater, looking NE (see arrow, upper left)
    with fumaroles present along a number of fractures to the N and E sides.
    The active crater is just out of view in the image foreground. Picture
    taken by Felipe Aguilera on 25 May 2005. Courtesy of Jose Viramonte and
    Lizzette Rodriguez.

    Figure 18. Schematic diagram showing the position of fumaroles on Lascar
    after the eruption on 4 May 2005. Also indicated are several new
    post-eruption fumaroles that developed on the S crater margin. Courtesy of
    Jose Viramonte and Lizzette Rodriguez.

    Recent and future work. A team of scientists from Michigan Technological
    University, the University of Hawaii, the Universidad Nacional de Salta,
    the Universidad de Chile, and the Universidad Nacional de Cordoba,
    conducted a field campaign at Lascar from 29 November to 8 December 2004.
    During this period, SO2 emissions were measured using two mini-UV
    spectrometers; aerosols were measured using two Microtops II sun
    photometers, and temperatures of the vent fumaroles were measured using a
    Forward Looking IR Radiometer (FLIR). Preliminary processing of the gas
    data showed a decrease since 2003 in the emissions, with SO2 fluxes around
    500 tons/day (Rodriguez et al., 2005). This contrasts with the fluxes
    determined by Mather et al. (2004) on January 2003, which were on the order
    of 2,300 tons/day. Observations of the SO2 index, using ASTER TIR images,
    have shown a decrease in the size of the SO2 anomaly from 2000 to the first
    half of 2004 (Castro Godoy and Viramonte, 2004).

    Temperature measurements made at the crater on 2 December 2004 by
    University of Hawaii scientists using a FLIR indicated low temperatures for
    the fumarole field, which represented a decrease when compared with the
    results of direct measurements conducted in October 2002 by Franco Tassi
    and others (Tassi et al., 2004; Bulletin v. 28, no. 3). Similar
    observations have been made using ASTER SWIR and TIR images (Silvia Castro,
    GEOSAR-AR program), which have shown a decrease in the absolute
    temperatures and the size of the thermal anomaly since October 2002 (Castro
    Godoy and Viramonte, 2004). Images during the month of April 2005 showed a
    slight increase in the area and maximum temperature of the anomaly at the
    beginning of the month, followed by a decrease at the end of April, prior
    to the eruption. Decreases in the thermal activity have been observed in
    previous eruptive cycles, prior to explosive events (Oppenheimer et al.,
    1993; Matthews et al., 1997).

    The data collected during the 2004 field campaign will help in the
    understanding of the pre-eruptive conditions at Lascar. SO2 emission rates
    on 7 December 2004 will be used to ground truth the satellite data from an
    ASTER overpass at 1436 UTC (1036 local time), and recently acquired ASTER
    data will be used to investigate SO2 emissions during the period close to
    the 4 May 2005 eruption. Scientists from Universita degli studi di Firenze
    (Italy), Universidad Catolica del Norte (Chile), and Universidad Nacional
    de Salta (Argentina) are conducting a systematic gas sample campaign at
    Lascar and other active volcanoes on the Central Volcanic Zone. Finally,
    scientists from the Universidad Catolica del Norte and the Universidad
    Nacional de Salta are processing data from Landsat TM and ETM+ images, with
    the objective of understanding the behavior of Lascar volcano during the
    1998-2004 period.

    References: Castro Godoy, S. and Viramonte, J.G., 2004, Micro FTIR field
    measurement for volcanic mapping, SO2 and temperature monitoring using
    ASTER images in Lascar Volcano, southern central Andes: IAVCEI General
    Assembly, Book of Abstracts, Pucon, Chile, 14-20 November.

    Mather, T.A., Tsanev, V.I., Pyle, D.M., McGonigle, A.J.S., Oppenheimer, C.,
    and Allen, A.G., 2004, Characterization and evolution of tropospheric
    plumes from Lascar and Villarrica volcanoes, Chile: Journal of Geophysical
    Research, v. 109.

    Matthews, S.J., Gardeweg, M.C., and Sparks, R.S.J., 1997, The 1984 to 1996
    cyclic activity of Lascar volcano, northern Chile: cycles of dome growth,
    dome subsidence, degassing and explosive eruptions: Bulletin of
    Volcanology, v. 59, p.72-82.

    Oppenheimer, C., Francis, P., Rothery, D., Carlton, D., and Glaze, L.,
    1993, Interpretation and comparison of volcanic thermal anomalies in
    Landsat Thematic Mapper infrared data: Volcan Lascar, Chile, 1984-1991:
    Journal of Geophysical Research, 98, p. 4269-4286.

    Rodriguez, L.A., Watson, I.M., Viramonte, J., Hards, V., Edmonds, M.,
    Cabrera, A., Oppenheimer, C., Rose, W.I., and Bluth, G.J.S., 2005, SO2
    conversion rates at Lascar and Soufriere Hills volcanoes: 9th Gas Workshop,
    Palermo, Italy, May 1-10.

    Tassi, F., Viramonte, J., Vaselli, O., Poodts, M., Aguilera, F., Martinez,
    C., Rodriguez, L.A., and Watson, I.M., 2004, First geochemical data from
    fumarolic gases at Lascar volcano, Chile: 32nd International Geological
    Congress, Florence, August 20-28, 2004.

    Background. Lascar is the most active volcano of the northern Chilean
    Andes. The andesitic-to-dacitic stratovolcano contains six overlapping
    summit craters. Prominent lava flows descend its NW flanks. An older,
    higher stratovolcano 5 km to the E, Volcan Aguas Calientes, displays a
    well-developed summit crater and a probable Holocene lava flow near its
    summit (de Silva and Francis, 1991). Lascar consists of two major edifices;
    activity began at the eastern volcano and then shifted to the western cone.
    The largest eruption of Lascar took place about 26,500 years ago, and
    following the eruption of the Tumbres scoria flow about 9,000 years ago,
    activity shifted back to the eastern edifice, where three overlapping
    craters were formed. Frequent small-to-moderate explosive eruptions have
    been recorded from Lascar in historical time since the mid-19th century,
    along with periodic larger eruptions that produced ashfall hundreds of
    kilometers away from the volcano. The largest historical eruption of Lascar
    took place in 1993, producing pyroclastic flows to 8.5 km NW of the summit
    and ashfall in Buenos Aires.

    Information Contacts: Raul Becchio and Jose G. Viramonte, Instituto
    GEONORTE and CONICET, Universidad Nacional de Salta, Buenos Aires 177,
    Salta 4400, Argentina (Email: viramont@unsa.edu.ar; URL:
    www.unsa.edu.ar/natura/); Lizzette A. Rodriguez and Matthew Watson,
    Michigan Technological University, Houghton, MI 49931, USA (Email:
    larodrig@mtu.edu; URL: www.geo.mtu.edu/volcanoes/); Felipe Aguilera,
    Universidad Catolica del Norte, Avenida Angamos 0610, Antofagasta, Chile
    (Email: faguilera@ucn.cl; URL: www.ucn.cl/FacultadesInstitutos/
    Fac_geologia.asp); Silvia Castro Godoy, GEOSAT-AR Project, SEGEMAR, Buenos
    Aires, Argentina (Email: silvia_castro_godoy@hotmail.com, URL:
    www.segemar.gov.ar/sensores...tos.htm); Matt Patrick and
    Rob Wright, HIGP-University of Hawaii, Honolulu, HI 96822, USA (Email:
    patrick@higp.hawaii.edu; URL: www.higp.hawaii.edu/volcanology.html);
    Sergio Haspert and Ricardo Valenti, VAAC Buenos Aires - Div. VMSR, Servicio
    Meteorologico Nacional, Argentina (Email: vmsr@meteo.edu.ar, URL:
    www.meteofa.mil.ar/).


    Rotorua
    New Zealand
    38.08°S, 176.27°E; summit elev. 757 m
    All times are local (= UTC + 11 hours)

    Bulletin v. 26, no. 3 reported hydrothermal activity at Rotorua on 26
    January 2001 involving the ejection of mud and ballistic blocks. Bulletin
    v. 28, no. 12 reported that the New Zealand Institute of Geological and
    Nuclear Sciences reported two subsequent hydrothermal eruptions in Rotorua
    caldera at Kuirau Park around 1100 on 6 November 2003 (figure 19). The
    eruptions occurred just meters from the site of the large blowout in 2001.
    The area is known for this kind of geothermal activity. The following
    information is primarily from Ashley Cody.

    Figure 19. Rotorua is the NW-most caldera of the Taupo volcanic zone, in
    the Bay of Plenty region of New Zealand's North Island. Courtesy of UNAVCO.

    In late May 2004 a geothermal well ~40 m deep at Tokaanu on Lake Taupo
    (~100 km S of Rotorua) blew out suddenly, erupting mud and scalding waters
    to ~15 m high and flooding surrounding properties for several days until it
    could be quenched and a new headworks fitted. This well may have been
    standing open and just suddenly began boiling, since its casing seemed to
    be intact.

    About 0100 on Saturday 29 June 2004 the blowout of a geothermal well in
    Rotorua blew muddy water and rubbly debris to ~15 m high and showered muck
    over houses and cars to a radius of ~100 m accompanied by noise "like a jet
    aircraft." It went on until about 0400 on 30 June 2004 when it was quenched
    with a pumped cold water supply. It was cement-grouted shut a few days
    later. The well was 100 m deep and cased to 47.5 m.

    Starting 18 July 2004 in the early afternoon, many earthquakes were
    strongly felt by many people in the area ~30 km N of Rotorua and ~20 km NW
    from Kawerau, in the northern North Island, or central Bay of Plenty. By 23
    July more than 200 earthquakes were recorded in this area, most at less
    than 10 km depth.

    In Lake Rotoehu, about 20 km N of Rotorua city, eyewitnesses reported a
    water column 100 m high that occurred at the same time as a strongly-felt
    ML 5.4 earthquake at about 1600 on 18 July 2004 at ~5 km depth. Shortly
    afterward a big series of waves occurred on the lake, and swept up beaches
    much higher than ever seen before.

    Ground rupturing was reported at several sites along southern shores of
    Lake Rotoehu. Many houses were evacuated due to damage such as walls
    breaking apart and houses shifting off their foundations. The main road was
    blocked in many places and more than 200 houses were evacuated due to their
    becoming unsafe to live in. Several people were killed by trees falling
    down banks onto cars and houses during the earthquakes.

    On Thursday 17 March 2005 at about 1435, a blowout was observed from the
    northern end of Ruapeka Bay on Lake Rotorua, at Ohinemutu. It shot dark
    grey muddy waters and steam to ~6 m for 3-4 minutes. An eyewitness called
    the council safety inspector, Peter Brownbridge. On 18 March at about 1500,
    the safety inspector saw two more shots each ~1 m high from the same spot
    in the lake. This previously unknown vent is ~25 m NW from a clear flowing
    hot spring known simply as S1233, in the bed of the lake just 10 m W of the
    tip of Muruika Point. This is where a prehistoric account relates of a
    sunken village, where a sudden disturbance occurred one night and many
    people were killed. From verbal genealogy records, this event may have
    occurred about early 1700s-1720s. Today rows of timber posts are still
    standing below water level in the lake here.

    According to a report in The Dominion Post by Mike Watson on 21 April 2005,
    one of the largest hydrothermal eruptions in the Rotorua area since 1948
    took place about 1030 on 19 April 2005 and was witnessed by two farmers
    (figure 20).

    Figure 20. The geothermal eruption roughly midway between Rotorua and Taupo
    on 19 April 2005 left a 50-m wide crater. Courtesy of Ashley Cody.

    A huge column of hot steam, mud and rocks was thrown 200 m in the air. The
    eruption happened in an inaccessible area at Ngatamariki scenic reserve,
    close to the Waikato River, and about 8 km from Orakei Korako geothermal
    springs, roughly halfway between Taupo and Rotorua. The column was visible
    10 km away and left a 50 m-wide crater and two hectares of debris. With the
    energy now taken out of the vent, no further eruption was expected.

    The major part of the eruption lasted about two hours but it was still
    spewing steam up to 10 m high five hours later. The eruption sent out
    7,000-10,000 m^3 of material. Mud and 50 cm-diameter rocks covered a 70-100
    m radius from the crater site, which had previously been covered by 2
    m-high blackberry bushes and fallen trees (figure 21). The ground may take
    months to cool. According to Ashley Cody, the site had been heating up in
    the past year, with three new hot springs forming.

    Figure 21. The hydrothermal eruption roughly halfway between Taupo and
    Rotorua left ash and mud covering the surrounding area to a depth of 4 m
    (light-colored material on ground surface, coating some trees, and choking
    the stream). Courtesy of Ashley Cody.

    Background. The 22-km-wide Rotorua caldera is the NW-most caldera of the
    Taupo volcanic zone. Rotorua is the only single-event caldera in the Taupo
    volcanic zone and was formed about 220,000 years ago following eruption of
    the >340 km^3 rhyolitic Mamaku Ignimbrite. Although caldera collapse
    occurred in a single event, the process was complex and involved multiple
    collapse blocks. The major city of Rotorua lies at the S end of the lake
    that fills much of the caldera. Post-collapse eruptive activity, which
    ceased during the Pleistocene, has been restricted to lava dome extrusion
    without major explosive activity. The youngest eruptive activity at Rotorua
    consisted of the eruption of three lava domes less than 25,000 years ago.
    The major thermal areas of Takeke, Tikitere, Lake Rotokawa, and
    Rotorua-Whakarewarewa are located within the caldera or outside its rim.
    Whakarewarewa contains New Zealand's last remaining active geyser field.

    Information Contacts: Ashley Cody and Ron Keam, Physics Department, The
    University of Auckland, Private Bag 92-019, Auckland, New Zealand (Email:
    ashley.cody@wave.co.nz, r.keam@auckland.ac.nz); Mike Watson, The Dominion
    Post.


    White Island
    New Zealand
    37.52°S, 177.18°E; summit elev. 321 m
    All times are local (= UTC + 11 hours)

    White Island was last reported on in Bulletin v. 29 no. 3, covering the
    period to March 2004. At that time, approximately two years had passed
    since any significant eruption, but the New Zealand Institute of Geological
    and Nuclear Sciences (GNS) continues to monitor White Island. This report
    is a summary of their brief reports.

    From April 2004 until June 2005, seismicity and hydrothermal activity at
    White Island remained at low levels, with some brief periods of weak to
    moderate volcanic tremor recorded during September to November of 2004. The
    level of the crater lake has risen significantly over this period, from
    12-13 m below the overflow level in April 2004 to only 3-4 m below overflow
    level in June 2005 (figure 22). Some of this increase was caused by
    landslides in July 2004 and by heavy rains in May 2005. Steam and gas
    emissions have been minor, with the exception of a large plume visible from
    the mainland on 15 October 2004. The alert level remained at 1 (on a scale
    of 0-5), indicating some degree of unrest but no threat of eruption.

    Figure 22. The crater lake on White Island, taken 9 January 2005, when the
    lake level was about 5 m below the overflow level and rising. Courtesy of
    Franz Jeker.

    Background. Uninhabited 2 x 2.4 km White Island, one of New Zealand's most
    active volcanoes, is the emergent summit of a 16 x 18 km submarine volcano
    in the Bay of Plenty about 50 km offshore of North Island. The 321-m-high
    island consists of two overlapping andesitic-to-dacitic stratovolcanoes;
    the summit crater appears to be breached to the SE because the shoreline
    corresponds to the level of several notches in the SE crater wall. Volckner
    Rocks, four sea stacks that are remnants of a lava dome, lie 5 km NNE of
    White Island. Intermittent moderate phreatomagmatic and strombolian
    eruptions have occurred at White Island throughout the short historical
    period beginning in 1826, but its activity also forms a prominent part of
    Maori legends. Formation of many new vents during the 19th and 20th
    centuries has produced rapid changes in crater floor topography. Collapse
    of the crater wall in 1914 produced a debris avalanche that buried
    buildings and workers at a sulfur-mining project.

    Information Contacts: Institute of Geological and Nuclear Sciences (GNS),
    Private Bag 2000, Wairakwi, New Zealand (URL: www.gns/cri.nz);
    GeoNet, a project sponsored by the New Zealand Government through these
    agencies: Earthquake Commission (E.C.), Geological and Nuclear Sciences
    (GNS), and Foundation for Research, Science and Technology (FAST). Geonet
    can be contacted at the above GNS address (URL:
    www.geonet.org.nz/contact.htm); Franz Jeker, Rigistrasse 10, 8173
    Neerach, Switzerland (Email: franz.jeker@swissonline.ch).
    __________________________________________________________
    Global Volcanism Program, NHB E-421 Tel: (202) 633-1800
    Smithsonian Institution Fax: (202) 357-2476
    Washington, DC 20560-0119 Email: gvp@si.edu

    Internet: www.volcano.si.edu/
  • Re: GVN Bulletin

    Thu, August 18, 2005 - 1:23 AM
    ****************************************************
    Bulletin of the Global Volcanism Network, June 2005
    ****************************************************
    From: Ed Venzke <venzke@volcano.si.edu>


    Bulletin of the Global Volcanism Network
    Volume 30, Number 6, June 2005

    Colima (Mexico) Explosions through June 2005,
    with repeated dome growth and destruction
    Soufriere Hills (Montserrat) Abundant ash-laden
    plumes, pyroclastic flows, and local ashfall
    St. Helens (Washington, USA) Extrusion of
    smooth-surfaced dome lavas that later crumbled; explosions
    Ebeko (Kurile Islands, Russia) Small ash deposits
    in January 2005 but plumes later became infrequent
    Shiveluch (Kamchatka, Russia) Lava dome growth,
    ash falls, pyroclastic flows during early to mid-2005
    Karymsky (Kamchatka, Russia) Several ash plumes,
    including two to ~ 8 km altitude, during mid-2005
    Canlaon (Philippines) May 2005 ash ejections
    ceasing after the 25th as monitored parameters declined
    Kilauea (Hawaii, USA) During November
    2004-January 2005 lava flows continued to enter the sea
    Tungurahua (Ecuador) Ash plumes and LP earthquakes still common in 2004-2005
    McDonald Islands (S Indian Ocean) Satellite
    infrared data suggests a new unwitnessed eruption

    Editors: Rick Wunderman, Catherine Galley, Edward Venzke, and Gari Mayberry
    Volunteer Staff: Robert Andrews, William Henoch,
    Jacquelyn Gluck, Jerome Hudis, and Stephen Bentley


    Colima
    Mexico
    19.514°N, 103.62°W; summit elev. 3,850 m
    All times are local (= UTC - 6 hours)

    Small to moderate explosive eruptions have been
    common at Colima since 1999, some blasting
    material as high as 11 km altitude and at times
    sending pyroclastic flows to 5 km runout
    distances. Between these explosive eruptions,
    andesitic lava from the main intracrater vent
    sometimes formed small, short-lived lava domes.
    The feeder lavas, cryptodomes, and occasional
    domes were blasted out during subsequent
    eruptions. A table of significant eruptive events
    at Colima during July 1999 to June 2005 (Luhr and
    others, in press) produced this tally for the
    number of days where plumes went over 2 km above
    the summit (~6 km altitude): in the latter half
    of 1999, three days; 2000, one day; 2001, four
    days; 2002, four days; 2003, 15 days; 2004, ~24
    days; and in the first half of 2005, 31 days.
    Eruptions discussed in aviation reports from the
    Washington Volcanic Ash Advisory Center (VAAC)
    became a significant source of data starting in
    2003, and formed the basis of many entries in the subsequent years.

    Extrusions during September-November 2004 formed
    a new lava dome in the active crater, and two
    lava flows descended from that crater along the N
    and WNW flanks (BGVN 30:01). After lava effusion
    ceased, intermittent explosions and exhalations
    followed. In the same pattern mentioned above,
    the dome was later destroyed by Vulcanian-style
    explosions that produced eruption plumes and in
    some cases, pyroclastic flows (BGVN 30:03).

    The number of seismic events decreased during
    December 2004-February 2005 (figure 1), and with
    some important exceptions, remained under 10
    events per day until as late as the end of June
    2005. During this reporting interval, April-June
    2005, intermittent explosions continued (figure
    1). Explosions that generated pyroclastic flows
    were known to have continued through at least 5 July.

    Figure 1. The number of daily earthquakes
    ascribed to rockfalls and pyroclastic flows
    (heavy line) and to explosions and exhalations
    (dashed line) at Colima during September
    2004-June 2005. Double arrows show the beginning
    (B) and the end (E) of the lava extrusion in late
    2004. A label indicates the period when
    occasional large explosions took place (an
    interval that began on 10 March and continued
    through June 2005). Courtesy of Colima Volcano Observatory.

    Comparatively large explosions began to occur
    starting 10 March 2005 (BGVN 30:03). The largest,
    accompanied by pyroclastic flows, were
    particularly vigorous from 24 May to 5 June. As
    in March 2004 the explosions consisted of
    Vulcanian-style gas-and-ash explosions. Some of
    the April-June explosions issued material that
    reached as high as ~10 km altitude, and
    pyroclastic flow runout distances reached up to
    ~5.1 km, an increase over those in March 2004
    (when maximum runout distances only reached ~2.8 km).

    When photographed on 25 May 2005 the dome and
    unconsolidated material filled much of the
    crater, although the intracrater area was
    anything but flat (figure 2). By comparison, a
    photo of the crater taken on 16 June 2005,
    following many large Vulcanian explosions, shows
    its upper portion to be essentially empty (figure 3).

    Figure 2. At Colima on 25 May 2005 the crater
    contained considerable dome and unconsolidated
    material, filling it to near the rim. Several
    weeks later, after further explosions had driven
    considerable material out, the upper crater was
    left with substantial open space (see next
    photo). Courtesy of Colima Volcano Observatory.

    Figure 3. Photo of Colima's crater after the
    comparatively large explosions that began in
    March 2005. This photo was taken on 16 June
    looking from the S. Eruptions had removed much of
    the crater fill and a small dome from the upper
    crater. Small impact craters pocked the crater
    floor. An erosion channel had developed across
    crater's S rim, presumably due to the passage of
    pyroclastic flows associated with the recent
    explosions. The notch in the rim has been
    prominent since 2004 and has emptied and perhaps
    grown considerably since the photo taken 25 May
    2005. Despite the changes seen in this photo, the
    explosions had left the crater walls intact and
    without evidence of fractures. Courtesy of Colima Volcano Observatory.

    The March-June explosive sequence removed the
    2004 lava dome, and left a crater ~260 m across
    and ~30 m deep (figure 3). No significant
    deformation of the volcanic edifice was recorded
    before or during the large explosions (table 1).
    After the explosion of 5 June, residents were
    evacuated from Juan Barragan, a small village ~10
    km SE of the summit. Smaller explosions at Colima
    typically take place at the rate of several per day.

    Table 1. Main characteristics of the largest
    explosions seen at Colima during May-June 2005.
    Column heights and ash cloud velocities came from
    remote-sensing data and reports furnished by the
    Washington VAAC. The highest velocity, 15 m/s,
    corresponds to 54 km/hour. Courtesy of Colima Volcano Observatory.

    Time of Altitude of Direction
    and average Length of the Length of
    explosion (UTC) the column horizontal
    velocity ash cloud in km* pyroclastic flows
    of the ash cloud

    24 May (0009) 9.7 km W (7.7
    m/s) 204 km 3.5 km
    30 May (0826) 8.5 km SE (15
    m/s) 102 km 4 km
    02 Jun (0449) 6 km S (5.1
    m/s) 74 km 4.5 km
    05 Jun (1920) 7.6 km W-SE (7.7
    m/s) 222 km 5.1 km

    Reference: Luhr, J., Navarro-Ochoa, C., and
    Savov, I., (in press), Petrology and mineralogy
    of lava and ash erupted from Volcan Colima,
    Mexico, during 1999-2005: Special Volume on the
    Colima Volcano, from the University of
    Guadalajara (edited by Francisco Nunez-Cornu).

    Background. The Colima volcanic complex is the
    most prominent volcanic center of the western
    Mexican Volcanic Belt. It consists of two
    southward-younging volcanoes, Nevado de Colima
    (the 4,320 m high point of the complex) on the N
    and the 3,850-m-high historically active Volcan
    de Colima at the S. A group of cinder cones of
    probable late-Pleistocene age is located on the
    floor of the Colima graben west and east of the
    Colima complex. Volcan de Colima (also known as
    Volcan Fuego) is a youthful stratovolcano
    constructed within a 5-km-wide caldera, breached
    to the S, that has been the source of large
    debris avalanches. Major slope failures have
    occurred repeatedly from both the Nevado and
    Colima cones, and have produced a thick apron of
    debris-avalanche deposits on three sides of the
    complex. Frequent historical eruptions date back
    to the 16th century. Occasional major explosive
    eruptions (most recently in 1913) have destroyed
    the summit and left a deep, steep-sided crater
    that was slowly refilled and then overtopped by lava dome growth.

    Information Contacts: Observatorio Vulcanologico
    de la Universidad de Colima, Colima, Col., 28045,
    Mexico (Email: ovc@cgic.ucol.mx); Washington
    Volcanic Ash Advisory Center (VAAC), NOAA-NESDES,
    Satellite Analysis Branch, 5200 Auth Road, Camp Springs, MD 20746 USA.


    Soufriere Hills
    Montserrat, West Indies
    16.72°N, 62.18°W; summit elev. 915 m
    All times are local (= UTC - 4 hours)

    Soufriere Hills was last reported on in BGVN
    30:03, covering November 2004 to March 2005,
    during which time the volcano remained quiet,
    with seismic signals, gas emissions and rockfalls
    all decreasing. This report, from Montserrat
    Volcano Observatory (MVO), covers the period from
    late March 2005 to July 2005. The volcano
    continued to be relatively quiet through April
    and early May, with activity increasing somewhat
    through June and several explosive events in late
    June and in July. Table 2 summarizes the
    seismicity and SO2 emissions during the period of this report.

    Table 2. Geophysical and geochemical data
    recorded at Soufriere Hills, 25 March 2005 to 15
    July 2005. * Only measurement during report
    period. **12-hour system failure may have caused
    events to be missed. Courtesy of MVO.

    Report date Seismicity Number of
    earthquakes SO2 flux (metric tons/day)

    (2005) level Hybrid VT
    LP Rockfalls Range Daily average

    25 Mar-01
    Apr low 1 5 1 -- 186-369 290
    01 Apr-08
    Apr low 1 7 1 -- 280-650 400
    08 Apr-15
    Apr low -- 19 -- -- 261-1877 619
    15 Apr-22
    Apr -- 7 37 -- 1 122-957 365
    22 Apr-29
    Apr -- 7 31 -- -- 112-330 304
    29 Apr-06
    May -- 1 4 -- 1 276-644 439
    06 May-13
    May -- 1 38 -- 1 221-537 398
    13 May-20
    May -- 3 18 -- -- 222-363 286
    20 May-27
    May -- -- 67 -- -- 880* --
    27 May-03
    Jun -- -- 8** -- -- 167-392 261
    03 Jun-10
    Jun -- -- 17 -- 1 142-671 399
    10 Jun-17
    Jun elevated 17 46 20 7 170-750 460
    17 Jun-24
    Jun elevated 8 4 5 3 430-1150 627
    24 Jun-01
    Jul elevated 19 15 5 -- 300-700 470
    01 Jul-08
    Jul elevated 15 9 11 11 241-1700 767

    Seismic activity at Soufriere Hills remained at
    low levels throughout March and most of April
    2005. Beginning on 15 April, vigorous
    steam-and-ash venting occurred on the NW side of
    Soufriere Hills crater and continued throughout
    the period of this report. Average daily SO2
    emissions were generally lower than the long-term
    eruption average of 500 tons/day, but increased in July to above the average.

    On 13 June at 0600 an ash plume reached a height
    of ~2.4 km altitude and drifted NE, depositing
    light ash in Lookout, Geralds, and St. Peters.

    Starting around 10 June, seismic and volcanic
    activity were at elevated levels. The ash venting
    that began on 13 June declined in intensity
    during the following week. The ash venting was
    caused by the rapid release of steam and other
    volcanic gases, possibly triggered by intense
    rainfall on the night of 12 June. Ash analyses
    from this episode did not indicate fresh magma.

    On 27 June a steam and ash cloud at ~3 km
    altitude was reported to be drifting W. By 28
    June satellite imagery showed a plume of ash and
    steam at ~1.8 km altitude extending NW. Periodic
    episodes of intense ash venting continued,
    culminating in an explosive event on 28 June at
    1306. During the event, ballistics were ejected
    onto the Farrell's plain (to the NW), and a
    column collapse produced pyroclastic flows. The
    pyroclastic flows reached the sea at the Tar
    River delta (to the NE), and a smaller volume of
    material flowed into the top of Tyre's Ghaut (to
    the N). Ash showed no evidence of fresh magma.

    Preliminary analysis of recent ground deformation
    data from the GPS network at the volcano showed
    that deflation during April to mid June 2005 had
    later reversed, and the volcano appeared to be
    inflating. Periodic ash venting continued and an
    explosion occurred on 3 July at 0130, which was
    similar to the explosion on 28 June.

    An explosive event at 0301 on 18 July caused
    widespread ash fallout between Fogarty Hill on
    the island's NW and Brodericks Yard on the
    island's SW and almost certainly led to
    pyroclastic flows to the sea in Tar River. This
    explosion was similar to, but slightly bigger
    than, the explosion on 3 July, and ash venting
    and pyroclastic flows combined to cause dramatic
    ash clouds which reached to at least 6 km. Winds
    blew the ash plume in a NW direction causing
    significant ash fall in Old Towne, Iles Bay,
    Salem, Olveston, Woodlands and St Peters. The
    maximum depth of ash measured by scientists in
    inhabited areas was 1.5 to 2.0 mm; the deepest
    ash was recorded at Weekes. Activity subsequently
    returned to background levels.

    The MVO collected ash samples from the affected
    areas to determine whether it was new material
    from depth or older material from the dome. Ash
    collected after the 28 June and 3 July 2005
    events showed no evidence of new magmatic material.

    On 28 July 2005, the Moderate Resolution Imaging
    Spectroradiometer (MODIS) flying onboard the Aqua
    satellite acquired an image of a plume of
    volcanic ash drifting westward in a slightly
    curving shape as it departs Soufriere Hills (in
    the middle of the image, figure 4).

    Figure 4. A MODIS image of an ash plume from
    Soufriere Hills acquired on 28 July 2005. N is
    towards the top. The plume was visible for over
    100 km, but conspicuous portions of the plume
    continued beyond the W (left) side of this image
    between the arrows. A Washington VAAC report from
    that day suggested a plume to ~ 5 km altitude and
    70-300 km long, blown W. Several islands
    neighboring Montserrat (M) are labeled: A,
    Antigua; B, Barbuda; G, Guadeloupe; N, Nevis; and
    SK, St. Kitts. For scale, the distance between
    the centers of the islands of Montserrat and
    Antigua is ~ 55 km. Some islands are ringed in
    bright blue-green, the possible result of coral
    reefs in shallow water, sediment, phytoplankton,
    or some combination of these conditions. Image
    and some elements of the caption courtesy of Jeff
    Schmaltz, MODIS Rapid Response Team, NASA.

    Background. The complex andesitic Soufriere Hills
    volcano occupies the southern half of the island
    of Montserrat. The summit area consists primarily
    of a series of lava domes emplaced along an
    ESE-trending zone. Prior to 1995, the youngest
    dome was Castle Peak, which was located in
    English's Crater, a 1-km-wide crater breached
    widely to the E. Block-and-ash flow and surge
    deposits associated with dome growth predominate
    in flank deposits. Non-eruptive seismic swarms
    occurred at 30-year intervals in the 20th
    century, but with the exception of a 17th-century
    eruption, no historical eruptions were recorded
    on Montserrat until 1995. Long-term
    small-to-moderate ash eruptions beginning in that
    year were later accompanied by lava dome growth
    and pyroclastic flows that forced evacuation of
    the southern half of the island and ultimately
    destroyed the capital city of Plymouth, causing
    major social and economic disruption to the island.

    Information Contact: Montserrat Volcano
    Observatory (MVO), Fleming, Montserrat, West Indies (URL: www.mvo.ms/).


    St. Helens
    Washington, USA
    46.20°N, 122.18°W; summit elev. 2,549 m
    All times are local (= UTC - 8 hours)

    Throughout the period covered by this report,
    March 2005 to July 2005, growth of the new lava
    dome inside the crater of St. Helens continued,
    accompanied by low rates of both seismicity and
    gas and ash emissions. The hazard status remained
    at 'Volcano Advisory' (Alert Level 2); aviation
    color code Orange. Results from a digital
    elevation model produced from imagery taken on 21
    February showed the highest part of the new lava
    dome was 12 m higher than on 1 February; during
    that 3 week period the volume of dome and
    surrounding uplift had increased by 3 million
    cubic meters. The average rate of growth
    continued at ~2 m^3/s. Figure 5 shows four views
    of changes to the lava dome during the period of
    this report. Figure 6 shows the seismicity and
    the time of the larger recognized explosions.

    Figure 5. Four views into St. Helens's crater
    from different perspectives and dates, focusing
    on the new dome. A: 15 March 2005, view from NE.
    The whaleback is close to its maximum length of
    500 m. Note that the glacier's heavily crevassed,
    half-moon shaped, E (left) arm lies squeezed
    between the growing dome and crater wall. Vent is
    steaming at lower-right whaleback. B: 3 May 2005,
    view from N. The whaleback has been breaking
    apart for several weeks. Note the large slab of
    smooth gouge-covered surface moving E (left). C:
    21 June 2005, view from NW. Note the development
    of broad talus on W (right) flank of dome. An
    isolated body of smooth gouge-covered surface to
    the right of the main spine is emerging from
    talus. D: 26 July 2005, view from E crater rim.
    The smooth, gouge-covered spine continues to
    crumble as a result of M$ 3 earthquakes and
    rockfalls. A large slab of March whaleback is
    visible at left. Most of the dome surface is now
    talus and disintegrating older whalebacks. By the
    end of July, the spine had been reduced to a
    highly fractured stump. All photos courtesy of USGS CVO.

    Figure 6. Magnitude of located earthquakes at
    Mount St. Helens through 27 July 2005 (Pacific
    Northwest Seismograph Network). Vertical lines
    represent the time of moderate explosions. Note
    periods of earthquakes M > 3 that accompanied
    dome break-ups in December, April, and July.
    Courtesy of CVO and the Pacific Northwest Seismograph Network.

    During 2-7 March, dome growth accompanied low
    rates of both seismicity and gas and ash
    emissions. Parts of the growing lava dome
    continued to crumble, forming rockfalls and
    generating small ash clouds that drifted out of
    the crater. The bulging ice on the deformed E arm
    of the glacier in the crater continued to move
    rapidly N at about 1.2 m per day (figure 7).

    Figure 7. A view of the growing dome at St.
    Helens from the Sugar Bowl camera just before the
    8 March 2005 explosion. The Sugar Bowl digital
    camera takes a picture every hour from its
    housing on the NE flanks. The image data are
    transmitted to a more accessible spot immediately
    after the pictures are taken. Courtesy of CVO.

    A small explosive event began at approximately
    1725 on 8 March. The eruption lasted about 30
    minutes with intensity gradually declining
    throughout; a fine dusting of ash from this event
    later fell ~100 km to NW (in Yakima, and
    Toppenish, Washington). By 0200 on 9 March, the
    leading edge of the faint, diffuse plume had
    reached ~300 km to the E (over western Montana).
    After the explosion scientists found the lava
    dome intact. They recognized ballistics (up to ~1
    m in diameter) as far as the N flank of the old
    lava dome and a lack of them along or beyond the
    crater rim. The explosion vented from the NNW
    side of the new lava dome, very near the source
    of the 1 October 2004 and 16 January 2005 explosions (figure 8).

    Figure 8. The 8 March 2005 explosion at St.
    Helens viewed from the Sugar Bowl camera. This
    shot was taken at about 1727 hours and 42 seconds on 8 March. Courtesy of CVO.

    The explosion on 8 March was one of the largest
    steam-and-ash emissions to occur since renewed
    activity began in October 2004. The Cascades
    Volcano Observatory (CVO) lost radio signals from
    three monitoring stations in the crater soon
    after the event started. The event followed a few
    hours of slightly increased seismicity not then
    interpreted as precursory. There were no other
    indications of an imminent change in activity.

    After the 8 March explosion, St. Helens only
    emitted steam, and seismicity dropped to a level
    similar to that during the several hours prior to
    the explosion. Gas emissions were very low,
    essentially unchanged from those measured in late
    February. The hazard status for the ongoing
    eruption, 'Volcano Advisory (Alert Level 2),'
    mentioned the possibility of events like the 8
    March explosion occurring without warning. That
    assessment remained unchanged and the hazard status stayed the same.

    Analysis of aerial photographs indicated that as
    of 10 March the topographic changes in the crater
    resulting from growth of the new dome and
    consequent glacier deformation had a combined
    volume of about 45 million m^3. The current
    eruption contributed new materials amounting to
    about two-thirds the volume of the old lava dome.

    From March 2005 through July 2005, growth of the
    new lava dome continued. Rates remained low for
    both seismicity and gas and ash emissions. CVO
    noted that during such eruptions, episodic
    changes in the level of activity can occur over
    days to months. During about 26-27 March, a group
    of M 2 to M 3 earthquakes occurred beneath the
    volcano, a level of activity considered normal during dome-emplacing volcanism.

    A series of large (M >=3) earthquakes occurred
    during 3-4 April, in addition to the typical
    array of smaller events. Observations on 6 April
    revealed that the smooth whaleback-shaped portion
    of the growing lava dome was broken by numerous
    fractures, and the edges had crumbled greatly.
    Several deep gashes on the E, N, and W sides
    frequently produced rockfalls and accompanying
    ash clouds. On 10 April the new dome continued to
    fracture and spread laterally. As a consequence,
    the dome's summit dropped by a few tens of meters
    over 2-3 weeks, leaving isolated high-standing
    remnants. This broken pattern was apparent in a
    photograph on 3 May (figure 5B).

    Earthquakes steadily decreased in magnitude and
    number through mid-April. A GPS receiver 200 m N
    of the new dome crept steadily NNW at ~10 cm per
    day. The combination of the GPS measurements
    adjacent to the lava dome and the qualitative
    estimate of lateral spreading suggested that
    extrusion of new lava continued during April.

    On the morning of 28 April there were reports of
    minor amounts of ashfall in the eastern part of
    the Portland metropolitan area, ~80 km SSW of St.
    Helens. There was no evidence of a new explosion.
    CVO scientists determined that large convective
    storms over the Cascades on 27 April entrained
    ash generated by the frequent hot rockfalls from
    the growing lava dome and kept it in suspension
    to fall out as far away as Portland.

    During early May poor weather obscured the
    volcano. Seismic and ground deformation activity
    remained unchanged. Through much of the night of
    4-5 May, however, VolcanoCam images detected
    intermittent glow from the new dome. The camera
    is mounted at the Johnston Ridge Observatory at
    an elevation of 1,400 m and ~6.5 km NNW of the
    volcano, a spot W of the S part of Spirit Lake.
    During 11-12 May images from the mouth of the
    crater showed the new spine of lava at the N end
    of the dome continuing to grow. Data from seismic
    and GPS instruments in the crater and on the
    outer flanks continued to lack significant
    changes over the past few weeks. Through the end
    of May, lava extrusion continued at the N end of
    the new lava dome, while the high spines
    continued to crumble. Other parts of the lava
    dome moved at the relatively low velocity of
    about 30 cm/day or remained stagnant. Table 3
    compares the older dome with the new one as of 3 May 2005.

    Table 3. A comparison of the old (1980-86) and
    new (2004-) domes at St. Helens. The new dome
    started in October 2004, and the reported data
    reflects conditions seen until 1 February 2005. Courtesy of CVO.

    Names Unnamed (the "old" dome) The "new" dome
    (unofficially
    called "the whaleback")

    Growth period 1980-1986 (six
    years) October 2004-February 2005 (and ongoing)

    Size - length ~ 1.1 km in diameter ~ 475 m long

    Size - width ~ 1.1 km in diameter ~ 152 m wide

    Elevation / 2.2 km, nearly 267
    m As of 1 February 2005, 2.3 km, nearly 415 m
    vertical height above the 1980
    crater above the 1980 crater floor, 152 m above the top
    floor.
    of the old 1980-86 lava dome, and 213 m above
    the
    2000 glacier surface. The new dome's top
    reached
    an elevation ~ 40 m below Shoestring
    Notch on the crater's SE rim.

    Volume ~ 75 x 10^6 m3 ~ 44 x 10^6 m3

    Around 4 June the rate of motion of a GPS unit on
    the NE part of the new dome slowed slightly,
    continuing to creep eastward and northward at a
    rate of several centimeters per day, but no
    longer rising vertically. The lava spine,
    however, continued to grow. Through the end of
    June 2005, seismic and deformation data continued
    trends similar to the previous few weeks, with
    small earthquakes approximately every 5 minutes,
    little to no movement of the old lava dome, minor
    movement of the N end of the new lava dome, and
    continued growth of the lava spine. Observations
    made on 15 June revealed that the lava spine
    continued to grow and that temperatures in cracks
    near the base of the spine were near 700°C.
    Thermal data from 15 June suggested that much of
    the W part of the dome was moving upward, as well
    as southward. During the last week of June, the
    smooth lava spine continued to grow at a rate of
    about 1.8-3.7 m per day. Rockfalls from the top
    of the spine kept its height from increasing by
    that same rate. Analysis of a digital elevation
    model made from imagery acquired on 15 June
    showed that the total volume addition to the
    crater since September 2004 had reached almost 60 million cubic meters.

    On 2 July at 0630 a rockfall from the growing
    lava dome removed a large piece of the dome's
    top, producing an ash plume that rose above the
    crater rim and generating a substantial seismic
    signal. Persistent smaller rockfalls from the
    growing lava dome built talus aprons on the W and NE flanks of the dome.

    On 12 July, CVO reported that rates of seismicity
    and ground deformation at Mount St. Helens had
    declined during the previous two weeks to some of
    the lowest levels since the eruption began in
    September 2004. A similar lull occurred in December 2004.

    Beginning 15 July and continuing through the end
    of the month, the growing spine and other high
    areas of the dome to the south produced numerous
    large rockfalls, most of which were associated
    with earthquakes of about M 3 (figure 9). Diffuse
    ash plumes that rose hundreds of meters above the
    rim were produced by the larger rockfalls. By the
    end of July most of the smooth gouge-covered
    surface of the spine had disintegrated, and the
    spine was reduced to a highly fractured, but
    still-extruding, stump surrounded by rapidly growing aprons of rockfall debris.

    Figure 9. Rockfall and accompanying ash cloud on
    26 July 2005 as viewed from station Brutus on the
    crater's E rim. Rockfall originated from the
    steep, fractured top of an inclined spine. Note
    boulders (light-colored specks against shadow)
    shooting ahead of ash cloud. Another spine is
    extruding from ground just behind the lower end
    of the ash cloud. Courtesy USGS and CVO.

    Background. Prior to 1980, Mount St. Helens
    formed a conical, youthful volcano sometimes
    known as the Fuji-san of America. During the 1980
    eruption the upper 400 m of the summit was
    removed by slope failure, leaving a 2 x 3.5 km
    horseshoe-shaped crater now partially filled by a
    lava dome. Mount St. Helens was formed during
    nine eruptive periods beginning about 40-50,000
    years ago and has been the most active volcano in
    the Cascade Range during the Holocene. Prior to
    2200 years ago, tephra, lava domes, and
    pyroclastic flows were erupted, forming the older
    St. Helens edifice, but few lava flows extended
    beyond the base of the volcano. The modern
    edifice was constructed during the last 2200
    years, when the volcano produced basaltic as well
    as andesitic and dacitic products from summit and
    flank vents. Historical eruptions in the 19th
    century originated from the Goat Rocks area on
    the N flank, and were witnessed by early settlers.

    Information Contacts: Cascades Volcano
    Observatory (CVO), U.S. Geological Survey, 1300
    SE Cardinal Court, Building 10, Suite 100,
    Vancouver, WA 98683-9589, USA (URL:
    vulcan.wr.usgs.gov/; Email:
    GSCVOWEB@usgs.gov); Pacific Northwest Seismograph
    Network (PNSN), Seismology Lab, University of
    Washington, Department of Earth and Space
    Sciences, Box 351310, Seattle, WA 98195-1310, USA
    (URL: www.pnsn.org/; Email: seis_info@ess.washington.edu).


    Ebeko
    Kurile Islands, Russia
    50.68°N, 156.02°E; summit elev. 1,156 m
    All times are local (= UTC +11 hours)

    A few gas-and-steam plumes from Ebeko were
    reported during February-April 2004 (BGVN 29:04).
    The most recent previous eruption was in January
    1991. On 30 January 2005 the Kamchatka Volcanic
    Eruptions Response Team (KVERT) raised the
    Concern Color Code at Ebeko from Green to Yellow
    after reports of a strong smell of sulfur on 27
    and 28 January in the town of Severo-Kurilsk, ~7 km from Ebeko.
    Observations by Leonid and Tatiana Kotenko in
    Severo-Kurilsk during May-July 2004 included
    occasional gas-and-steam plume rising as high as
    250 m above the volcano during clear weather and
    fumarolic plumes moving close to the ground.
    There was no visible activity in August, but a
    few plumes were seen again from September to November.

    During 28 January, a white gas-and-steam plume
    was seen from Severo-Kurilsk rising 400 m above
    the volcano. Summit observations the next day
    revealed a yellow-gray, 5-m-diameter, column
    rising 300 m from a vent on the NE side of the
    active crater. Three ash layers 2-3 mm thick were
    noted 10 m from the vent, and ash extended ~500 m
    E into the crater. At this time a new 7 x 12 m
    turquoise lake had developed in the SW part of
    the active crater. The lake disappeared on 30
    January, and there was intensive fumarolic
    activity where it had been. Shallow earthquakes
    were recorded at the Severo-Kurilsk seismic station.

    On 1 February gas-and-steam plumes rose to 450 m
    above Ebeko's crater and drifted NE. On 7
    February a small emission of steam, gas, and
    possibly ash rose ~1 km above the crater and
    drifted ~12 km SE. On 8 and 9 February plumes
    rose to 600 m and thin ash deposits were noted in the town of Severo-Kurilsk.

    The following information came to KVERT from
    observers in Severo-Kurilsk (Leonid and Tatiana
    Kotenko). On 15-16 February a dark-gray column
    rose up to 500 m above the crater. A dark-gray
    plume extended 6 km E and a light-gray plume 7 km
    SE. On 16 February ashfall together with snowfall
    was noted over the strait to the E of Paramushir
    Island. On 17 February a white column up to 250 m
    above the crater was observed. On 12 February and
    16-17 February a strong smell of a H2S was noted
    at Severo-Kurilsk. On 18-19 February white
    gas-and-steam columns 5 m in diameter rose from
    the two vents up to 450 m above the crater and a
    new lake (10 x 10 m) on the floor of the active
    crater was observed. On 25 February white
    gas-and-steam plumes rose to 450 m and 1,000 m
    above the crater. Gas-and-steam plumes were also
    observed on 1-2, 4-5, and 9 March. No ash was
    seen. A strong smell of H2S was noted at
    Severo-Kurilsk on 25 February and 2 March.

    About 20 seismic events of less than Ml 2.0 were
    observed during 1-9 March at the Severo-Kurilsk
    seismic station. No seismic activity was observed
    from 12 to 14 March. On 15 March two seismic
    events were noted. There was no seismicity during
    18-25 March, so KVERT reduced the hazard status
    from Yellow to Green, the lowest level.

    The Russian Emergency Situations Ministry's
    Sakhalin department reported renewed activity on
    27 June in the form of emission clouds rising to
    a maximum height of 200 m above the crater and
    drifting SW. KVERT did not report any activity,
    and the Concern Color Code for Ebeko remained at Green.

    Background. The flat-topped summit of the central
    cone of Ebeko volcano, one of the most active in
    the Kuril Islands, occupies the northern end of
    Paramushir Island. Three summit craters located
    along a SSW-NNE line form Ebeko volcano proper,
    at the northern end of a complex of five volcanic
    cones. Blocky lava flows extend W from Ebeko and
    SE from the neighboring Nezametnyi cone. The
    eastern part of the southern crater of Ebeko
    contains strong solfataras and a large boiling
    spring. The central crater of Ebeko is filled by
    a lake about 20 m deep whose shores are lined
    with steaming solfataras; the northern crater
    lies across a narrow, low barrier from the
    central crater and contains a small, cold
    crescent-shaped lake. Historical activity,
    recorded since the late-18th century, has been
    restricted to small-to-moderate explosive
    eruptions from the summit craters. Intense
    fumarolic activity occurs in the summit craters
    of Ebeko, on the outer flanks of the cone, and in lateral explosion craters.

    Information Contacts: Olga Girina, Kamchatka
    Volcanic Eruptions Response Team (KVERT), a
    cooperative program of the Institute of Volcanic
    Geology and Geochemistry, Far East Division,
    Russian Academy of Sciences, Piip Ave. 9,
    Petropavlovsk-Kamchatskii 683006, Russia (Email:
    girina@kcs.iks.ru); Alaska Volcano Observatory
    (AVO), cooperative program of the U.S. Geological
    Survey, 4200 University Drive, Anchorage, AK
    99508-4667, USA (URL: www.avo.alaska.edu/;
    Email: tlmurray@usgs.gov), the Geophysical
    Institute, University of Alaska, P.O. Box 757320,
    Fairbanks, AK 99775-7320, USA (Email:
    eisch@dino.gi.alaska.edu), and the Alaska
    Division of Geological and Geophysical Surveys,
    794 University Ave., Suite 200, Fairbanks, AK
    99709, USA (Email: cnye@giseis.alaska.edu).


    Shiveluch
    Kamchatka, Russia
    56.653°N, 161.360°E; summit elev. 3,283 m
    All times are local (= UTC + 12 hours [+ 13 hours in March-June])

    Following explosions from Shiveluch during 25
    February to 4 March 2005 ash fell in
    Ust'-Hairyuzovo, about 250 km W (BGVN 30:02).
    From March 2005 until July 2005, Shiveluch
    remained at Concern Color Code Orange. Throughout
    March 2005 the lava dome at Shiveluch continued
    to grow and on several days ash-and-gas plumes
    and gas-and-steam plumes rose to a maximum of
    ~2.8 km above the dome. Satellite imagery showed
    a thermal anomaly at the dome during the first
    week of March and a large thermal anomaly over
    the recent pyroclastic-flow deposit during 11-12
    March. Between 5-28 March a new lava extrusion
    added ~50 m height to the SW part of the dome.

    During April 2005, intensive growth of the new
    extrusion at the W part of the dome continued,
    and the E and W parts of the lava dome became
    nearly level. Gas-and-steam plumes rose to a
    maximum of ~1.2 km above the dome during April
    2005. Satellite imagery showed a large thermal
    anomaly at the dome during mid-April and a small
    anomaly associated with a pyroclastic flow on 19
    April. On 25 April, a hot avalanche on the dome's
    W side produced an ash plume that rose ~2 km
    above the 2.5-km-high lava dome. Growth of the
    dome continued during May 2005 with a new
    extrusion to the W. Ash-and-gas plumes, some
    rising 2 km above the dome, were frequent.
    Satellite imagery showed a persistent thermal
    anomaly at the lava dome throughout May.
    The dome continued to grow during June 2005.
    During 3-10 June, two shallow M 1.6-1.7
    earthquakes occurred 0-5 km beneath the active
    dome. Gas-and-steam plumes rose as high as 400 m
    above the dome during June. A persistent thermal
    anomaly was visible throughout June. Fumarolic
    activity was reported during the week of 18-24
    June. During the last week of June, satellite
    imagery showed a persistent thermal anomaly, and
    fumarolic activity produced steam to 4-5 km
    altitude. On 30 June, ash-and-gas plumes rose 3-5
    km altitude. and drifted NW. Hot avalanches of
    volcanic material were also recorded. On 6 July
    ash-and-gas plumes rose to ~7 km altitude and
    drifted NW. On 7 July an 11-minute-long seismic
    event occurred, and ash-and-gas plumes may have
    reached a height of 10 km altitude. Around 8
    July, KVERT raised the Concern Color Code from
    Orange to Red, the highest level. On 8 July 2005,
    video footage showed weak gas-and-steam plumes
    rising to ~5 km altitude. On 9 July 2005, the
    Concern Color Code was reduced to Orange.

    Background. The high, isolated massif of
    Shiveluch volcano (also spelled Sheveluch) rises
    above the lowlands NNE of the Kliuchevskaya
    volcano group. The 1300 cu km Shiveluch is one of
    Kamchatka's largest and most active volcanic
    structures. The summit of roughly 65,000-year-old
    Strary Shiveluch is truncated by a broad
    9-km-wide late-Pleistocene caldera breached to
    the south. Many lava domes dot its outer flanks.
    The Molodoy Shiveluch lava dome complex was
    constructed during the Holocene within the large
    horseshoe-shaped caldera; Holocene lava dome
    extrusion also took place on the flanks of Strary
    Shiveluch. At least 60 large eruptions of
    Shiveluch have occurred during the Holocene,
    making it the most vigorous andesitic volcano of
    the Kuril-Kamchatka arc. Widespread tephra layers
    from these eruptions have provided valuable time
    markers for dating volcanic events in Kamchatka.
    Frequent collapses of dome complexes, most
    recently in 1964, have produced debris avalanches
    whose deposits cover much of the floor of the breached caldera.

    Information Contacts: Olga A. Girina, Kamchatka
    Volcanic Eruptions Response Team (KVERT), a
    cooperative program of the Institute of Volcanic
    Geology and Geochemistry, Far East Division,
    Russian Academy of Sciences, Piip Ave. 9,
    Petropavlovsk-Kamchatskii 683006, Russia (Email:
    girina@kcs.iks.ru), the Kamchatka Experimental
    and Methodical Seismological Department (KEMSD),
    GS RAS (Russia), and the Alaska Volcano
    Observatory (USA); Alaska Volcano Observatory
    (AVO), a cooperative program of the U.S.
    Geological Survey, 4200 University Drive,
    Anchorage, AK 99508-4667, USA (URL:
    www.avo.alaska.edu/; Email:
    tlmurray@usgs.gov), the Geophysical Institute,
    University of Alaska, P.O. Box 757320, Fairbanks,
    AK 99775-7320, USA (Email:
    eisch@dino.gi.alaska.edu), and the Alaska
    Division of Geological and Geophysical Surveys,
    794 University Ave., Suite 200, Fairbanks, AK
    99709, USA (Email: cnye@giseis.alaska.edu).


    Karymsky
    Kamchatka, Russia
    54.05°N, 159.43°E; summit elev. 1,536 m
    All times are local (= UTC + 12 hours)

    During 1 January to mid-April 2004 (BGVN 29:04),
    ash-and-gas explosions and gas plumes were
    observed and seismicity remained generally above
    background levels. From May to the beginning of
    September 2004, seismic activity remained above
    background levels, varying over this time from
    100-800 small shallow earthquakes per day.
    Ash-and-gas explosions and gas plumes to a
    maximum height of 7.5 km were frequent. On 1
    September 2004 an increase in activity led the
    Kamchatka Volcanic Eruptions Response Team
    (KVERT) to raise the Concern Color Code from
    Yellow to Orange. From September to December
    2004, seismicity remained above background
    levels, and ash-and-gas explosions and ash plumes
    were frequent. On 12 November the hazard status was lowered to Yellow.

    Increasing seismicity, rock avalanches and
    possible ash plumes to 2.5 km altitude led KVERT
    to raise the Concern Color Code to Orange again
    on 7 December 2004. On 28 December, an observed
    eruption at Karymsky produced a plume composed
    primarily of gas and steam, but with some ash,
    that rose to ~1 km above the crater. Thermal
    anomalies were also visible on satellite imagery
    on 27 and 28 December. On 30 December the Tokyo
    VAAC reported that a plume was present up to ~8 km altitude extending SW.

    There were no seismic data from 12 December 2004
    till late January 2005. Through January and
    February thermal anomalies were frequently
    visible on satellite imagery. Seismicity remained
    above background levels from February 2005 through July 2005.
    Through March and April 2005, ash-and-gas
    explosions and gas plumes were frequent. Ash
    deposits extended 10-15 km S and SW of the
    volcano. On 20 April, volcanic bombs rose to 50 m
    above the crater, and ash fell to the NE on 21
    April. On 26 and 27 April, Strombolian activity
    was seen in two of the volcano's craters;
    volcanic bombs rose to ~300 m above the craters.
    Ash fell to the SE on 22-23 April and
    pyroclastic-flow deposits were seen on the NNW
    flank of the volcano. During May 2005,
    ash-and-gas explosions and plumes were again
    frequent, and a thermal anomaly continued to be visible on satellite imagery.

    Due to a decrease in seismic and volcanic
    activity during 3-10 June, KVERT decreased the
    alert level from Orange to Yellow. Seismic
    activity increased starting on 22 June. Ash
    explosions up to 3,000 m altitude traveling SW
    were observed by pilots. According to seismic
    data, about 10 ash-and-gas plumes and avalanches
    occurred at the volcano. On 23 June KVERT
    increased the alert level to Orange. Satellite
    imagery of Karymsky showed a narrow ash-and-gas
    plume at a height of ~3.5 km altitude on 30 June.
    Based on interpretations of seismic data,
    ash-and-gas plumes may have reached 3 km above the crater.

    The Tokyo VAAC posted four messages on Karymsky
    during the 90 days prior to 8 August 2005; in
    each, ash was not identifiable from satellite.
    The earliest, 18 May was similar to the last one,
    on 23 June. Both noted a reported plume to FL100
    ('flight level 100' signifies 10,000 feet; 3.05
    km altitude). Reports on 22 and 24 May both noted
    ash to FL 120 (3.65 km altitude).

    Background. Karymsky, the most active volcano of
    Kamchatka's eastern volcanic zone, is a
    symmetrical stratovolcano constructed within a
    5-km-wide caldera that formed during the early
    Holocene. The caldera cuts the south side of the
    Pleistocene Dvor volcano and is located outside
    the north margin of the large mid-Pleistocene
    Polovinka caldera, which contains the smaller
    Akademia Nauk and Odnoboky calderas. Most
    seismicity preceding Karymsky eruptions
    originated beneath Akademia Nauk caldera, which
    is located immediately S of Karymsky volcano. The
    caldera enclosing Karymsky volcano formed about
    7600-7700 radiocarbon years ago; construction of
    the Karymsky stratovolcano began about 2000 years
    later. The latest eruptive period began about 500
    years ago, following a 2300-year quiescence. Much
    of the cone is mantled by lava flows less than
    200 years old. Historical eruptions have been
    vulcanian or vulcanian-strombolian with moderate
    explosive activity and occasional lava flows from the summit crater.

    Information Contacts: KVERT (see Shiveluch);
    Tokyo Volcanic Ash Advisory Center (VAAC), Japan
    Meteorological Agency, Tokyo Aviation Weather
    Service Center, Haneda Airport 3-3-1, Ota-ku,
    Tokyo 144-0041, Japan (URL:
    www.jma.go.jp/JMA_HP/jma/...enter/vaac/;
    Email: vaac@eqvol.kishou.go.jp).


    Canlaon
    central Philippines
    10.412°N, 123.132°E; summit elev. 2,435 m
    All times are local (= UTC + 8 hours)

    Throughout May 2005, PHIVOLCS noted that
    ash-and-steam emissions from Canlaon produced
    plumes to 500-1,000 m above the volcano. The
    hazard status remained at Alert Level 1. The SO2
    flux remained above the 'normal' level of 500
    metric tons/day (t/d) with values of 2,700 t/d on
    1 May, 2,080 on 22 May, and 1,400 on 26 May.
    According to news reports, flights to and from
    nearby Kalibo airport were suspended on 3 May due to reduced visibility.

    Although voluminous white steam continued to be
    discharged from the active vent early in June
    2005, after 25 May ash ejections stopped and ash
    contents in the steam plume were significantly
    reduced. On 3 June PHIVOLCS lowered the hazard
    status of Canlaon from Alert Level 1 to Alert
    Level Zero, listing a variety of reasons. For
    one, they noted the downtrend in the SO2 gas
    emission rate from a high of about 4,900 t/d, to
    the prevailing level of 1,500 t/d. For another,
    they noted the absence of significant seismic
    activity before, during, and after the ash
    emissions. And finally, they cited a lack of
    significant observations indicating near-surface
    hydrothermal activity. Since Canlaon has a
    history of sudden outbursts, the public was
    reminded to refrain from entering the 4-km-radius
    Permanent Danger Zone (PDZ) and to coordinate
    with PHIVOLCS and Disaster Management Councils in
    any attempt to climb the volcano.

    Background. Canlaon volcano (also spelled
    Kanlaon), the most active of the central
    Philippines, forms the highest point on the
    island of Negros. The massive 2435-m-high
    stratovolcano is dotted with fissure-controlled
    pyroclastic cones and craters, many of which are
    filled by lakes. The summit of Canlaon contains a
    broad elongated northern caldera with a crater
    lake and a smaller, but higher, historically
    active crater to the south. The largest debris
    avalanche known in the Philippines traveled 33 km
    to the SW from Canlaon. Historical eruptions,
    recorded since 1866, have typically consisted of
    phreatic explosions of small-to-moderate size
    that produce minor ashfalls near the volcano.

    Information Contacts: Philippine Institute of
    Volcanology and Seismology (PHIVOLCS), Department
    of Science and Technology, PHIVOLCS Building,
    C.P. Garcia Avenue, Univ. of the Philippines
    Campus, Diliman, Quezon City, Philippines (URL:
    www.phivolcs.dost.gov.ph/); Chris Newhall,
    USGS, Box 351310, University of Washington,
    Seattle, WA 98195-1310, USA(Email:
    cnewhall@ess.washington.edu); Philippine Star (URL: www.philstar.com/).


    Kilauea
    Hawaiian Islands, USA
    19.425°N, 155.292°W; summit elev. 1,222 m
    All times are local (= UTC - 10 hours)

    Activity at Kilauea through October 2004 was
    previously reviewed in reports that included maps
    showing the extent of key lava flows through most
    of August 2004 (BGVN 29:09). During November 2004
    through January 2005, lava flows were abundant
    and made complex patterns. Their overall advance
    can be seen by comparing maps of the extent of
    the lava flows as of late August 2004 (figure 10)
    and 2 February 2005 (figure 11).

    Figure 10. Kilauea lava flows erupted during
    activity from 1983-August 2004 of Pu`u `O`o and
    Kupaianaha. Note the location of Kupaianaha, the
    active vent area during 1986-1992, ~ 4 km ENE of
    Pu`u `O`o. Courtesy of the U.S. Geological
    Survey's Hawaiian Volcano Observatory.

    Figure 11. Kilauea lava flows erupted during
    activity from 1983-2 February 2005 of Pu`u `O`o
    and Kupaianaha. Courtesy of the U.S. Geological
    Survey's Hawaiian Volcano Observatory.

    On 4 November 2004 lava from the Prince Kuhio
    Kalaniana `ole (PKK) flow entered the sea,
    forming a new delta seaward of the E end of the
    old Lae'apuki delta. The PKK flow has been
    continuously active since 26 July 2004, and lava
    continued to enter the sea through 26 November
    2004. This was the first time lava entered the
    sea since the Banana lava flow ceased in early
    August 2004. The Banana flow developed from
    breakouts when lava escaped from the confines of
    the Mother's Day lava tube, emerging near the
    former Banana Tree kipuka. This flow stagnated
    early in September 2004, and the Mother's Day
    tube ceased carrying lava late in 2004.

    During the first week in December 2004, the lava
    flow at Lae'apuki abated. Activity resumed during
    the second week along all areas of the PKK flow
    from high on the Pulama pali fault scarp. By 13
    December lava again entered the sea at the East
    Lae'apuki delta. The flow moderated during the
    second half of December with only several areas
    of visible surface lava apparent on the Pulama
    pali fault scarp and on the coast.

    New vents opened at the southern base of Pu`u
    `O`o on 19 January 2004 and fed the Martin Luther
    King (MLK) flows (figure 11). The PKK flow
    originated from two vents ~250 m S of the base of
    Pu `u `O`o. By 2 February 2005 the PKK flow had
    entered the sea at West Highcastle, Lae'apuki, and Ka`ili`ili (figure 11).

    During January 2005, surface lava was visible
    along the three main arms of the PKK flow as they
    advanced downslope towards the coast (figure11).
    The middle arm of the PKK flow was comparatively
    small, and it failed to reach the ocean during
    this reporting interval; it remained high on
    Pulama pali. In contrast, lava from the E and W
    arms of the PKK flow began to enter the ocean on
    31 January. The large E arm of the PKK lava flow
    fed the larger Ka`ili`ili entry. The W branch of
    the PKK lava flow once supplied lava to Lae'apuki
    (an E branch of the W arm), but later also began
    feeding the West Highcastle ocean entry (the W branch of the W arm, figure 11).

    Seismicity. After seven months of relative
    quiescence renewed seismicity and numerous small
    long-period (LP) events again became visible in
    November 2004 on the North Pit seismogram.
    Elevated activity began on 16 November, peaking
    at over 2,000 events a day by late November
    (figure 12). Nearly all of these earthquakes were
    too small to catalog. To obtain this plot, a
    daily event count was extrapolated from a
    representative part of the North Pit (NPT)
    seismogram. Scientists combined the counts for
    two shallow (0-5 km deep) earthquake types, those
    designated by HVO as short-period summit or
    short-period caldera (SPC) and those designated
    as shallow, long-period (long-period caldera A,
    LPC-A) earthquakes. The similar frequency content
    of these two kinds of earthquakes make them
    difficult to distinguish on the drum record. In
    addition, small-magnitude deeper earthquakes,
    designated as long-period earthquakes originating
    at depths over 5 km, may have also registered
    within the summit caldera to appear on the plot,
    although they would be expected to contain a
    lower dominant frequency of oscillation than the
    LPC-A earthquakes. Tremor episodes were rare or absent.

    Figure 12. A time series of Kilauea's daily
    earthquakes (SPC, LPC-A, and possibly LPC-C
    types) registered at the summit during October
    2004 through January 2005. Courtesy of U.S.
    Geological Survey's Hawaiian Volcano Observatory.

    A minor peak in seismicity occurred in later
    January, during the two days before and after the
    25 January inflation-deflation event. Most of the
    events on 25 January appeared to be of the SPC variety.

    Tilt and deformation. The tiltmeter record at
    Kilauea summit (UWE) and Pu`u `O`o (POC) showed
    numerous correlated tilt changes, with a short
    time delay between UWE and POC stations and
    larger magnitude delays at POC (figure 13). One
    of the largest of these deformations took place
    on 25-26 November and resulted in about 3
    microradians of tilt at UWE, and 5 microradians
    at POC. This was similar in character to the tilt
    events of recent months, starting with fairly
    rapid deflation, followed by a similar rate and
    magnitude of inflation. Though they differ in
    character from the deflation-inflation-deflation
    (DID) cycles of the past few years, they seem to
    be originating from the same shallow storage area
    near Halemaumau, the crater at Kilauea's summit.

    Figure 13. Electronic tiltmeter records from the
    N flank of Pu`u `O`o cone (POC) and NW rim of
    Kilauea caldera (UWE) for (A) October and
    November 2004 and (B) December 2004 through
    January 2005. Only the radial component is
    plotted, i.e., the direction that maximizes
    signal from the most common sources of tilt at
    both locations. Courtesy of U.S. Geological
    Survey's Hawaiian Volcano Observatory.

    Kilauea continued to inflate over this reporting
    period. The extension rate across the summit
    increased dramatically in early January 2005,
    from an average rate of about 8 cm/yr to over 40
    cm/yr. There was a short inflation-deflation
    event on 25 January, followed by about 2-3 days
    of extremely rapid movement of the S flank;
    continuous GPS stations on the S coast were
    displaced by up to 2 cm. The pattern and rate of
    motion are very similar to the slow earthquake of
    November 2000. The slip event occurred during a
    swarm of earthquakes (see seismic section
    above), but the cumulative magnitude of these
    earthquakes was not nearly as great as the
    estimated equivalent moment magnitude of the slip.

    Other large episodes of correlated multistation
    tilt occurred on 14 December 2004 and 25 January
    2005. In December, both UWE and POC recorded
    deflationary tilts of about 4 and 2.5
    microradians, respectively, over about 12 hours.
    In mid-January, the summit started showing a high
    rate of inflationary tilt, coinciding with the
    increase in cross-summit extension, measured by
    continuously recording GPS. In the early morning
    of 25 January, summit tiltmeters and POC recorded
    a rapid inflation (about 5.5 microradians in an
    hour at UWE, 2 at POC) followed by an equal
    amount of deflation over the next day. The event
    was similar to the fairly frequent
    deflation-inflation-deflation (DID) events at
    Kilauea. Similarities included the apparent
    source regions of the inflation, the seismic
    signature, the delay time between the summit and
    the rift zone, and the timing of increased activity.

    SO2 emission rate measurements. Summit SO2
    emission rates for October/November ranged from
    80 to 130 metric tons per day (t/d) with an
    average of 105 t/d (standard deviation, s.d.=20
    t/d for 36 measurements made over 6 days).
    Although this represents a slight decrease over
    emission rates measured during the previous
    reporting period, it does not represent a
    significant change. Correlation spectrometer
    (COSPEC) SO2 measurements along the Chain of
    Craters Road yielded SO2 flux rates of
    1,080-1,660 t/d with a mean value of 1,270 t/d
    (s.d. of 260 t/d for 27 measurements made over 4
    days). The drop in emissions, which began in May
    2004, had continued through November 2004. A lack
    of trade winds hindered SO2 flux measurements
    during November and December. Six traverses on 6
    December yielded an emission rate of 105 t/d
    (s.d.=10 t/d) consistent with the more frequent
    measurements made during September-October 2004.
    The return of the tradewinds in early February
    allowed measurements to resume and showed that
    summit emissions had decreased markedly, likely
    due to the heavy rainfall on 4 February.

    Background. Kilauea volcano, which overlaps the E
    flank of the massive Mauna Loa shield volcano,
    has been Hawaii's most active volcano during
    historical time. Eruptions of Kilauea are
    prominent in Polynesian legends; written
    documentation extending back to only 1820 records
    frequent summit and flank lava flow eruptions
    that were interspersed with periods of long-term
    lava lake activity that lasted until 1924 at
    Halemaumau crater, within the summit caldera. The
    3 x 5 km caldera was formed in several stages
    about 1500 years ago and during the 18th century;
    eruptions have also originated from the lengthy
    East and SW rift zones, which extend to the sea
    on both sides of the volcano. About 90% of the
    surface of the basaltic shield volcano is formed
    of lava flows less than about 1,100 years old;
    70% of the volcano's surface is younger than 600
    years. A long-term eruption from the East rift
    zone that began in 1983 has produced lava flows
    covering more than 100 km^2, destroying nearly
    200 houses and adding new coastline to the island.

    Information Contact: Hawaiian Volcano Observatory
    (HVO), U.S. Geological Survey, PO Box 51, Hawaii
    National Park, HI 96718, USA (URL:
    hvo.wr.usgs.gov/; Email: hvo-info@hvomail.wr.usgs.gov).


    Tungurahua
    Ecuador
    1.467°S, 78.442°W: summit elev. 5,023 m
    All times are local (= UTC - 5 hours)

    The eruption of Tungurahua that began at the end
    of December 2003 (BGVN 28:11) continued through
    January 2004 (BGVN 29:01). Figure 14 shows an ash
    plume emitted on January 2004 in a Moderate
    Resolution Imaging Spectroradiometer (MODIS) image.

    Figure 14. A NASA MODIS image showing an ash
    plume from Tungurahua acquired 14 January 2004. N
    is up; the plume's height and length were
    undisclosed. Arrow points to Tungurahua and is
    along the approximate trend of the densest
    portion of the plume. The plume blew NE across
    the Andes and remained visible well over the
    thickly vegetated lowlands farther E. (Visible
    Earth v1 ID 26233.) Courtesy of NASA. Inset map
    showing major active Ecuadorian volcanoes courtesy of the USGS.

    On 5 February 2004 there was a slight increase in
    seismic activity at Tungurahua; steam emissions
    rose to low levels, and small lahars traveled
    down the volcano's W flank via the Achupashal and
    Chontapamba gorges. On 9 February emissions of
    steam, gas, and moderate amounts of ash occurred,
    deposited to the W in the sectors of Pillate and
    San Juan. During mid February, several avalanches
    of incandescent volcanic blocks traveled ~1 km
    down the volcano's flank. During late February
    through mid April 2004, degassing continued at
    Tungurahua with occasional explosions of steam,
    gas, and ash, producing plumes to ~500 m above the volcano.

    On 2, 11, and 15 March lahars traveled through
    the Pampas sector. During the night of 28-29
    March incandescent material was observed
    avalanching on the upper slopes. From 30 March to
    3 April, volcanic activity was at relatively low
    levels, but emissions of steam and ash occurred,
    and incandescence was visible in the crater. On 4
    April at 1902 an explosion produced a plume
    containing a moderate amount of ash that rose to
    800 m above the crater, and on the evenings of 10
    and 11 April, incandescence was visible in the crater.

    Sulfur-dioxide flux measurements taken on 11
    April were the highest measured for several
    weeks; 1,600-1,700 metric tons per day. Heavy
    rain during the afternoon and night of 13 April
    triggered a lahar that cut the La Pampa section of the Banos-Pelileo road.

    Volcanic activity at Tungurahua at the end of
    April 2004 was at moderate levels. On 21 April, a
    column of steam, gas, and ash rose to a height of
    ~1 km above the volcano and drifted NW. Ash fell
    in Bilbao, Cusua, San Juan, Cotalo, Pillate, and
    Juive sectors. A plume reached ~0.5 km on 22
    April and deposited ash in the towns of Ambato
    (to the NW) and Banos (to the N). During the
    evening of 24 April, incandescence was visible in
    the crater, and incandescent blocks rolled a few
    meters down the volcano's NW flank.
    Volcano-tectonic earthquakes on 27 and 28 April
    preceded a slight increase in the number of
    sudden explosions at Tungurahua on 30 April.
    According to news reports, ash fell in the towns
    of Cotalo, and San Juan (W of the volcano) on 1
    and 2 May. The level of seismicity at Tungurahua
    decreased on 4 May. On 12 May, an explosion
    produced an ash cloud to ~3 km above the volcano
    that drifted SW, and on 13 May seismicity
    increased moderately, related to the increased
    numbers of emissions. Incandescence was visible
    at the lava dome during some nights.

    From mid May through June, small-to-moderate
    emissions of gas, steam, and ash continued at
    Tungurahua. The highest rising plume reached ~2.5
    km above the volcano on 23 May. On the morning of
    19 May a mudflow occurred in the Pampas sector,
    but it did not affect the highway. Strombolian
    activity was visible in the crater on the evening
    of 23 May. During 2-8 June, activity remained
    moderate with several weak to moderate
    explosions recorded per day. Sporadically
    observed gas-and-ash and gas-and-steam plumes
    rose up to 1 km above the summit. A strong
    explosion on 5 June produced a gas-and-ash plume
    that rose 2 km above the summit. All plumes
    drifted W. Seismicity remained at moderate
    levels. On 3 June, possible lahars were noted on the N and NW flanks.

    Several explosions occurred on 10 June, with the
    largest rising ~3 km above Tungurahua's summit
    and drifting W. A small amount of ash fell in the
    Pillate area, and a lahar destroyed a bridge in
    the Bibao zone. During mid to late June, there
    was a slight increase in volcanic activity at
    Tungurahua in comparison to the previous weeks.
    There were several emissions of steam, gas, and
    moderate amounts of ash, and 5-10 explosions
    occurred daily. Seismicity was characterized by long-period earthquakes.

    From July through December 2004 the level of
    volcanic and seismic activity diminished at
    Tungurahua, with sporadic moderate explosions of
    ash and gas. The highest rising plume reached
    ~1.5 km above the volcano. Seismicity was at
    relatively low levels. Incandescence in the
    crater was observed at night on several
    occasions. Some explosions on 20 September
    generated plumes with ash, causing ashfall in
    Bilbao and Pondoa, and on the evening of 21
    September, Strombolian activity was seen, with
    volcanic blocks thrown as high as 200 m above the
    volcano. On 27 October an explosion produced an
    ash column to a height of ~3.5 km above the
    volcano. During the evening, ash fell in the
    towns of Banos, Runton, and El Salado. Explosions
    on 31 October also deposited small amounts of ash
    in Bilbao and Motilone, and on 15 November,
    incandescence was observed in the crater of the
    volcano and explosions generated steam columns
    with moderate ash content that rose ~2 km above
    the crater and drifted S. During 22-27 December,
    activity at Tungurahua consisted of
    small-to-moderate explosions, several long-
    period earthquakes, and episodes of tremor.
    Emissions of steam, gas, and small amounts of ash
    rose a maximum of 1.5 km on 22 December.

    Increased seismicity and volcanic tremor
    registered at Tungurahua during early January
    2005. There were eleven signals suggesting
    volcanic emissions and one small explosion.
    Seismicity then returned to a low level. On 11
    January, steam plumes rose ~300 m above the
    volcano and extended WNW, and incandescence was
    observed emanating from the crater during 12-13
    January. On 14 January, a white column of
    steam-and-gas was observed that reached a height
    of 500 m above the crater and extended to the NW.
    A steam- and-gas plume reached a height of
    200-300 m above the crater on 16 January, and extended SE.

    The Washington Volcanic Ash Advisory Center
    (VAAC) reported 18 January that an ash plume
    reached ~5.5 km altitude and extended to the E of
    Tungurahua's summit for ~15 km. During 19-24
    January 2005, there were several emissions from
    Tungurahua of steam, gas, and ash. The plumes
    that were produced rose to a maximum height of ~1
    km above the volcano and drifted in multiple
    directions, small amounts of ash falling in the
    sectors of Agoyan, San Francisco, Runton, Pondoa,
    and Banos. Seismicity was at relatively low
    levels. Ash emission from Tungurahua on the
    evening of 25 January 2005 deposited a small
    amount of ash in the sector of Puela; ash was
    deposited on the volcano's N and W flanks on 26
    January. The character of the eruption changed on
    30 January to low-energy emissions of
    predominately steam. This type of activity continued through 31 January.

    Volcanic and seismic activity was at low levels
    at Tungurahua during the period of February-mid
    July 2005. Low- energy plumes were emitted, and
    long-period earthquakes were recorded. Ashfall
    was reported in towns near the volcano, including
    Puela (SW of the volcano), San Juan de Pillate,
    Cusuaua, and Quern. On 23 February the daily
    sulfur-dioxide flux was 1,200 tons/day. On 27 and
    28 February, rains generated lahars in the W zone
    of the volcano into the gorges of Cusua and
    Bilbao. A moderate explosion occurred 18 April at
    2057 that sent incandescent volcanic blocks
    rolling down the volcano's flanks. Ash fell S of
    the city of Ambato. On 20 and 21 April rain
    generated lahars that traveled down the volcano's
    W flank near the settlement of Bilbao (8 km W).
    An emission on 19 May around 1200 produced an
    ash-and- steam plume to ~500 m altitude that
    drifted N. On 7 June fine ash fell in the Puela
    sector, ~8 km SW of the volcano. On 24 June a
    narrow plume was identified in multispectal
    satellite imagery about an hour after an ash
    eruption was observed by the Instituto Geofisica.
    The ash plume was at an altitude of ~5.5 km and
    extended 35-45 km W from the summit. On 4 July
    2005, low-energy plumes were emitted that rose to
    a maximum of ~5.8 km altitude.

    Table 4 gives examples of some seismic statistics
    for several months during the reporting period
    from the Instituto Geofisico-Escuela Politecnica Nacional (IG).

    Table 4. Summary of available seismicity (number
    of events) at Tungurahua during January
    2004-March 2005 as published in IG monthly
    reports of March 2004, October 2004, and April
    2005. Courtesy of the Instituto Geofisico-Escuela Politecnica Nacional (IG).

    Month/Year Long-period
    Volcano-tectonic Emission Explosions Hybrid

    Jan
    2004 365 6 217 28 0
    Feb
    2004 255 8 147 16 0
    Mar
    2004 123 7 123 2 0
    Aug
    2004 620 5 142 22 0
    Sep
    2004 674 9 119 43 0
    Oct
    2004 390 14 168 53 0
    Jan
    2005 138 8 92 6 0
    Feb
    2005 113 20 29 0 0
    Mar
    2005 54 20 1 0 0

    Background. Tungurahua, a steep-sided,
    andesitic-dacitic stratovolcano that towers more
    than 3 km above its northern base, is one of
    Ecuador's most active volcanoes. Three major
    volcanic edifices have been sequentially
    constructed since the mid-Pleistocene over a
    basement of metamorphic rocks. Tungurahua II was
    built within the past 14,000 years following the
    collapse of the initial edifice. Tungurahua II
    itself collapsed about 3000 years ago and
    produced a large debris-avalanche deposit and a
    horseshoe-shaped caldera open to the west, inside
    which the modern glacier-capped stratovolcano
    (Tungurahua III) was constructed. Historical
    eruptions have all originated from the summit
    crater. They have been accompanied by strong
    explosions and sometimes by pyroclastic flows and
    lava flows that reached populated areas at the
    volcano's base. Prior to a long-term eruption
    beginning in 1995 that caused the temporary
    evacuation of the city of Banos at the foot of
    the volcano, the last major eruption had occurred
    from 1916 to 1918, although minor activity continued until 1925.

    Information Contacts: Geophysical Institute (IG),
    Escuela Politecnica Nacional, Apartado
    17-01-2759, Quito, Ecuador (URL:
    www.igepn.edu.ec/); Washington Volcanic
    Ash Advisory Center (VAAC), Satellite Analysis
    Branch (SAB), NOAA/NESDIS E/SP23, NOAA Science
    Center Room 401, 5200 Auth Rd., Camp Springs, MD
    20746 USA (URL: www.ssd.noaa.gov/);
    Jacques Descloitres, MODIS Rapid Response Team,
    NASA/GSFC, 8800 Greenbelt Road, Greenbelt, MD
    20771, USA (URL:
    earthobservatory.nasa.gov/Natur...ards/;
    rapidfire.sci.gsfc.nasa.gov/).


    McDonald Islands
    Southern Indian Ocean
    53.03°S, 72.60°E; summit elev. 230 m

    The following report comes from Matt Patrick of
    the HIGP Thermal Alerts Team. Two night-time
    ASTER images (Band 10, 8.3 microns, at 90 m pixel
    size) of McDonald Island show activity centered
    on the NW shore of the island. The December 2002
    image was examined some months ago, but it was
    not determined whether the long-wave infrared
    (IR) anomaly was genuine, since it was relatively
    low intensity and there was no anomaly in the
    shortwave IR. The most recent ASTER image (12
    July 2005) shows a somewhat larger long-wave IR
    anomaly, but more importantly, there are five
    pixels in the shortwave IR (Band 9, 2.4 microns;
    not shown) which are saturated, indicating this
    is a significantly hot target. Based upon
    McDonald's typical activity, the anomaly probably
    reflects low-level effusive activity.

    The first and only MODVOLC alert pixel showed up
    in November 2004 (BGVN 29:12). These ASTER images
    show that recent activity is centered around the
    NW flank of the island, very close to shore.
    Comparing the July 2005 image with the December
    2002 image, there might be an indication of the
    shoreline growing westward, but it is hard to
    tell for sure with this resolution (90 meters).
    The location of this activity is generally
    consistent with recent BGVN reports: in 1999
    steaming was observed on the N-NE part of the
    island (BGVN 24:01), and a recent Landsat ETM
    image indicated that island construction over the
    last two decades has expanded the northern
    portion of the volcano (BGVN 26:02 and 27:12).

    Andrew Tupper noted that he found the hot spot
    identification plausible. The question of edifice
    collapse and possible tsunami generation
    associated with McDonald Islands has recently
    been a subject of interest but little technical
    information is available on topics such as
    edifice morphology and slope stability.

    Background. Historical eruptions have greatly
    modified the morphology of the McDonald Islands,
    located on the Kerguelen Plateau about 75 km west
    of Heard Island. The largest island, McDonald, is
    composed of a layered phonolitic tuff plateau cut
    by phonolitic dikes and lava domes. A possible
    nearby active submarine center was inferred from
    phonolitic pumice that washed up on Heard Island
    in 1992. Volcanic plumes were observed in
    December 1996 and January 1997 from McDonald
    Island. During March of 1997 the crew of a vessel
    that sailed near the island noted vigorous
    steaming from a vent at the northern side of the
    island along with possible pyroclastic deposits
    and lava flows. A satellite image taken in
    November 2001 showed the island to have more than
    doubled in area since previous reported
    observations in November 2000. The high point of
    the island group had shifted to the northern end
    of McDonald Island, which had merged with Flat Island.

    Information Contacts: Matt Patrick, HIGP Thermal
    Alerts Team, Hawai'i Institute of Geophysics and
    Planetology (HIGP) / School of Ocean and Earth
    Science and Technology (SOEST), University of
    Hawai'i, 2525 Correa Road, Honolulu, HI 96822,
    USA (hotspot.higp.hawaii.edu/, Email:
    patrick@higp.hawaii.edu); Andrew Tupper, Darwin
    Volcanic Ash Advisory Centre (VAAC), Commonwealth
    Bureau of Meteorology, Northern Territory
    Regional Office, PO Box 40050, Casuarina, NT
    0811, Australia (URL:
    www.bom.gov.au/info/vaac/; Email: darwin.vaac@bom.gov.au).
    __________________________________________________________
    Global Volcanism Program, NHB E-421 Tel: (202) 633-1800
    Smithsonian Institution Fax: (202) 357-2476
    Washington, DC 20560-0119 Email: gvp@si.edu

    Internet: www.volcano.si.edu/

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