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by Michael Reilly
Last year, 72 volcanoes erupted around the world -- that's a lot of fire, and slightly above average. So far 2009 looks like it's off to a fast start, too, with Mount Redoubt letting loose in Alaska, Japan's Mount Asama raining ash on Tokyo and an undersea volcano in Tonga breaching the surface and growing an island. But none of these is likely to break into our list of Top 10 Volcanoes in Geologic History. Most of these come with signs that read "Danger: Keep Back at Least One Continent." But if this list of past catastrophe teaches us anything, it's that the biggest, baddest volcanoes can erupt anywhere and at any time. And they will again -- it's just a matter of when.
10. Ontong-Java Plateau, South Pacific
This is the biggest volcano you've never heard of.
When it erupted 125 million years ago, it covered a region of the south Pacific Ocean the size of Alaska with basalt, in some places as much as 30 kilometers thick. It was so big, the eruption itself is thought to have lasted 6 million years.
Scientists call this type of volcano a large igneous province (LIP). They are highly mysterious, and appear to form when huge amounts of hot magma well up from thousands of miles deep in the mantle, near Earth's core.
There's a lot of debate as to whether LIPs erupt in huge explosions, or just ooze out in massive sheets of lava. Either way, mass extinctions have a tendency to occur whenever one of these things go off, so it's probably a good thing we've never seen one in action.
Credit: Larry O'Hanlon
9. Mount St. Helens, Washington, USA
May 18, 1980 was a bad day in Washington State.
Silent for over 100 years, the picturesque 9,677-foot peak had by late April grown into a bloated, trembling blister of rock and magma. And like a blister, it popped early on a Sunday morning, rocketing fiery ash out to the north at close to the speed of sound.
The eruption killed 57 people and did almost $3 billion in damage when all was said and done. It also lopped 1,314 off the height of the mountain, which was reduced to a smoldering crater.
This was the most deadly volcanic eruption in Unites States history - and it was just a pipsqueak, really.
Credit: USGS
8. Grimsvotn, Iceland
Nothing says "explosion" quite like mixing of searing hot magma with ice from a glacier.
It's a common circumstance at Grimsvotn, a volcano buried underneath the Vatnajokull glacier in Eastern Iceland that last erupted in 2004.
Each time Grimsvotn erupts, huge amounts of liquid build up under the glacier until the pressure becomes so great that the water literally lifts up the glacier and escapes in catastrophic floods, called "jokulhlaups."
You don't want to be around for a jokulhlaup.
The flood that came after the 1996 Grimsvotn eruption discharged 50,000 cubic meters of water per second, making it briefly the second largest river in the world. But that kind of thing doesn't faze Icelanders – these are the same folks who once sprayed sea water on a lava flow to keep it from engulfing a nearby harbor town.
Credit: USGS
7. Mauna Kea, Hawaii, USA
Given the violent company it's in, Mauna Kea is pretty chill.
Dormant for the last 4,500 years, it was never much of an exploder even in its heyday. That's because the lava that comes out of volcanoes in Hawaii is a low-viscosity basalt – it tends to ooze and flow like a river.
Shown here with snowy peaks in the foreground, the mountain has erupted a lot of lava over the eons. It is only 13,796 feet above sea level, but from its base at the bottom of the Pacific, it measures 33,476 feet high, making it the tallest mountain in the world. Its upper reaches used to have enough snow for skiing (and further back, glaciers).
Credit: NASA
6. Krakatau, Indonesia
In 1883, humanity witnessed what scientists call a "caldera-forming eruption" in Indonesia. In plain English, we call that a mountain blowing itself apart.
At 200 megatons of explosive power, the eruption was four times more powerful than the biggest nuclear bomb ever detonated.
Since the volcano and island were one in the same, there wasn't much left after the explosion rocked the Sunda Strait and sent 100-foot high tsunamis and scalding ash flows ashore up to 25 miles away. In the ruined void the volcano left behind, a new island has been growing back (through a series of much smaller eruptions) and is now around 1,000 feet high.
Credit: NASA
5. Ra Patera, Io, Jupiter's Moon
Thanks to space exploration, the list of greatest volcanoes can no longer be restricted to Earth. In 1979 the Voyager space probe made a shocking discovery -- Jupiter's moon Io was pock-marked with active volcanoes.
Voyager's snapshot of Ra Patera was the first discovery of an active extraterrestrial volcano, though the bigger vents Loki and Pele were discovered soon after.
But it didn't make sense.
Io is about same the size as Earth's moon, which long ago froze in the vacuum of space. So why was it still active? As scientists soon learned, Jupiter's intense gravity was tugging on Io's innards, creating such heat that the moon was literally disemboweling itself, spewing sulfur-rich lavas all over the surface of the moon, and out into space.
Credit: NASA
4. Santorini, Greece
Look at the small group of five islands known as Santorini, and it's clear something bad once happened there. In fact, the islands all were one, until an eruption bigger than Krakatau blew the place apart about 3,600 years ago. Ash deposits 100 feet thick have been found 19 miles in all directions from the caldera.
Shown here is a wall of the volcano where you can see layers of ash, lava flows, pyroclastic deposits and other volcanic products.
The ancient eruption is thought to have spawned the tales of the "Lost City of Atlantis" and perhaps even hastened the collapse of the Minoan civilization on the nearby island of Crete.
Credit: NOAA/Dimitris Sakellariou, Hellenic Center for Marine Research
3. Olympus Mons, Mars
The biggest volcano in the solar system is also the quietest.
It's the size of Arizona, and close to 90,000 feet high, but this gentle giant hasn't erupted in millions of years. When it did it was probably a lot like Mauna Kea, leaking rivers of liquid rock rather than exploding into the Martian skies.
Credit: NASA
2. Tambora, Indonesia
Between dozens of volcanoes, the biggest earthquakes in the world, and devastating tsunamis, Indonesia's got a lot of geology to worry about. And Mount Tambora, a huge volcano on the island of Sumbawa, is no exception.
The mountain produced a gargantuan eruption in 1815 that produced an ash cloud so big, it canceled the summer of 1816 in North America and Europe.
The eruption also killed between 70,000 and 90,000 people, making it the deadliest in human history.
And the number ONE volcano in geologic history is... (you saw this one coming)...
Credit: NASA
1. Siberian Traps, Siberia
A LIP just like Ontong-Java, the Siberian Traps supervolcano has one distinct difference: it is by far the deadliest volcano the planet has ever seen.
The traps erupted at the end of the Permian era, 250 million years ago. It was the worst mass extinction the planet has ever seen; 90 percent of all life on Earth was wiped out.
The massive traps basalts appear to be the smoking gun. They seeped into huge coal deposits on their way to the surface and their enormous heat baked the coal, sending billions of tons of greenhouse gases into the atmosphere. The global warming that followed was catastrophic - it took millions of years for life on Earth to recover.
Credit: NASA
Article posted February 27, 2009.
dsc.discovery.com/earth/sli...index.html
Last year, 72 volcanoes erupted around the world -- that's a lot of fire, and slightly above average. So far 2009 looks like it's off to a fast start, too, with Mount Redoubt letting loose in Alaska, Japan's Mount Asama raining ash on Tokyo and an undersea volcano in Tonga breaching the surface and growing an island. But none of these is likely to break into our list of Top 10 Volcanoes in Geologic History. Most of these come with signs that read "Danger: Keep Back at Least One Continent." But if this list of past catastrophe teaches us anything, it's that the biggest, baddest volcanoes can erupt anywhere and at any time. And they will again -- it's just a matter of when.
10. Ontong-Java Plateau, South Pacific
This is the biggest volcano you've never heard of.
When it erupted 125 million years ago, it covered a region of the south Pacific Ocean the size of Alaska with basalt, in some places as much as 30 kilometers thick. It was so big, the eruption itself is thought to have lasted 6 million years.
Scientists call this type of volcano a large igneous province (LIP). They are highly mysterious, and appear to form when huge amounts of hot magma well up from thousands of miles deep in the mantle, near Earth's core.
There's a lot of debate as to whether LIPs erupt in huge explosions, or just ooze out in massive sheets of lava. Either way, mass extinctions have a tendency to occur whenever one of these things go off, so it's probably a good thing we've never seen one in action.
Credit: Larry O'Hanlon
9. Mount St. Helens, Washington, USA
May 18, 1980 was a bad day in Washington State.
Silent for over 100 years, the picturesque 9,677-foot peak had by late April grown into a bloated, trembling blister of rock and magma. And like a blister, it popped early on a Sunday morning, rocketing fiery ash out to the north at close to the speed of sound.
The eruption killed 57 people and did almost $3 billion in damage when all was said and done. It also lopped 1,314 off the height of the mountain, which was reduced to a smoldering crater.
This was the most deadly volcanic eruption in Unites States history - and it was just a pipsqueak, really.
Credit: USGS
8. Grimsvotn, Iceland
Nothing says "explosion" quite like mixing of searing hot magma with ice from a glacier.
It's a common circumstance at Grimsvotn, a volcano buried underneath the Vatnajokull glacier in Eastern Iceland that last erupted in 2004.
Each time Grimsvotn erupts, huge amounts of liquid build up under the glacier until the pressure becomes so great that the water literally lifts up the glacier and escapes in catastrophic floods, called "jokulhlaups."
You don't want to be around for a jokulhlaup.
The flood that came after the 1996 Grimsvotn eruption discharged 50,000 cubic meters of water per second, making it briefly the second largest river in the world. But that kind of thing doesn't faze Icelanders – these are the same folks who once sprayed sea water on a lava flow to keep it from engulfing a nearby harbor town.
Credit: USGS
7. Mauna Kea, Hawaii, USA
Given the violent company it's in, Mauna Kea is pretty chill.
Dormant for the last 4,500 years, it was never much of an exploder even in its heyday. That's because the lava that comes out of volcanoes in Hawaii is a low-viscosity basalt – it tends to ooze and flow like a river.
Shown here with snowy peaks in the foreground, the mountain has erupted a lot of lava over the eons. It is only 13,796 feet above sea level, but from its base at the bottom of the Pacific, it measures 33,476 feet high, making it the tallest mountain in the world. Its upper reaches used to have enough snow for skiing (and further back, glaciers).
Credit: NASA
6. Krakatau, Indonesia
In 1883, humanity witnessed what scientists call a "caldera-forming eruption" in Indonesia. In plain English, we call that a mountain blowing itself apart.
At 200 megatons of explosive power, the eruption was four times more powerful than the biggest nuclear bomb ever detonated.
Since the volcano and island were one in the same, there wasn't much left after the explosion rocked the Sunda Strait and sent 100-foot high tsunamis and scalding ash flows ashore up to 25 miles away. In the ruined void the volcano left behind, a new island has been growing back (through a series of much smaller eruptions) and is now around 1,000 feet high.
Credit: NASA
5. Ra Patera, Io, Jupiter's Moon
Thanks to space exploration, the list of greatest volcanoes can no longer be restricted to Earth. In 1979 the Voyager space probe made a shocking discovery -- Jupiter's moon Io was pock-marked with active volcanoes.
Voyager's snapshot of Ra Patera was the first discovery of an active extraterrestrial volcano, though the bigger vents Loki and Pele were discovered soon after.
But it didn't make sense.
Io is about same the size as Earth's moon, which long ago froze in the vacuum of space. So why was it still active? As scientists soon learned, Jupiter's intense gravity was tugging on Io's innards, creating such heat that the moon was literally disemboweling itself, spewing sulfur-rich lavas all over the surface of the moon, and out into space.
Credit: NASA
4. Santorini, Greece
Look at the small group of five islands known as Santorini, and it's clear something bad once happened there. In fact, the islands all were one, until an eruption bigger than Krakatau blew the place apart about 3,600 years ago. Ash deposits 100 feet thick have been found 19 miles in all directions from the caldera.
Shown here is a wall of the volcano where you can see layers of ash, lava flows, pyroclastic deposits and other volcanic products.
The ancient eruption is thought to have spawned the tales of the "Lost City of Atlantis" and perhaps even hastened the collapse of the Minoan civilization on the nearby island of Crete.
Credit: NOAA/Dimitris Sakellariou, Hellenic Center for Marine Research
3. Olympus Mons, Mars
The biggest volcano in the solar system is also the quietest.
It's the size of Arizona, and close to 90,000 feet high, but this gentle giant hasn't erupted in millions of years. When it did it was probably a lot like Mauna Kea, leaking rivers of liquid rock rather than exploding into the Martian skies.
Credit: NASA
2. Tambora, Indonesia
Between dozens of volcanoes, the biggest earthquakes in the world, and devastating tsunamis, Indonesia's got a lot of geology to worry about. And Mount Tambora, a huge volcano on the island of Sumbawa, is no exception.
The mountain produced a gargantuan eruption in 1815 that produced an ash cloud so big, it canceled the summer of 1816 in North America and Europe.
The eruption also killed between 70,000 and 90,000 people, making it the deadliest in human history.
And the number ONE volcano in geologic history is... (you saw this one coming)...
Credit: NASA
1. Siberian Traps, Siberia
A LIP just like Ontong-Java, the Siberian Traps supervolcano has one distinct difference: it is by far the deadliest volcano the planet has ever seen.
The traps erupted at the end of the Permian era, 250 million years ago. It was the worst mass extinction the planet has ever seen; 90 percent of all life on Earth was wiped out.
The massive traps basalts appear to be the smoking gun. They seeped into huge coal deposits on their way to the surface and their enormous heat baked the coal, sending billions of tons of greenhouse gases into the atmosphere. The global warming that followed was catastrophic - it took millions of years for life on Earth to recover.
Credit: NASA
Article posted February 27, 2009.
dsc.discovery.com/earth/sli...index.html
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Re: TOP 10 VOLCANOES IN GEOLOGIC HISTORY
Tue, March 24, 2009 - 1:19 AMAnchorage (AFP) March 23, 2009
Alaskan authorities were on alert Monday after the Mount Redoubt volcano erupted five times, spewing plumes of smoke and ash some 15 kilometers (nine miles) into the air and forcing flight cancellations.
The Alaska Volcano Observatory said there were no immediate reports of casualties or damage from the 3,100 meter (10,200-foot) volcano, located not far from Anchorage, Alaska's most populous city.
Weeks of eruptions can be expected, officials said, similar to Mount Redoubt's last major eruption, when the volcano belched on and off for some four months starting in December 1989.
The eruptions, which began late Sunday, have unleashed a cloud of ash reaching up to 18,200 meters (60,000 feet) above sea level, said Rick Wessels, a geophysicist at the observatory. The explosions were also "pretty good sized," he said.
Alaska Airlines canceled 19 flights out of the international airport in Anchorage, which lies some 160 kilometers (100 miles) northeast of the volcano, and residents of nearby towns have been warned to prepare for falling ash.
"We expect these activities to last for weeks," said Interior Secretary Ken Salazar, speaking with volcano experts on a conference call to reporters.
Salazar said that Alaska officials were monitoring the safety of local residents and that of air travelers. Some 20,000 passengers fly through the area "on any given day," Salazar said.
Officials are also monitoring the Drift River Oil Terminal, an oil storage site located on Redoubt Bay, just 32 kilometers (20 miles) northeast of the volcano.
When the volcano last erupted, lava that crashed into the Drift River triggered a flood that reached the oil terminal, which was briefly evacuated.
Police in Anchorage earlier distributed flyers warning of the danger of hot ash.
The volcano observatory, which monitors activity at the state's 44 volcanos, reported at least five powerful eruptions on Mount Redoubt, including the first late Sunday.
Staff have been on alert since the volcano first began rumbling again in January, but a 24-hour watch has now been resumed and a red alert warning has been posted, the observatory said.
Early Monday the prevailing winds were pushing the ash north to the upper Susitna Valley and Talkeetna, known as a starting point for mountaineers attempting to climb Mount McKinley, the highest peak in North America.
"The ash is moving north and missing the bulk of the population in south-central Alaska," said US Geological Survey volcano expert Tom Murray, warning that eruptions "could go on for weeks."
Murray confirmed that ash had landed 160 kilometers (100 miles) north of the volcano.
The National Weather Service issued an ash fall advisory for towns including Talkeetna and Willow, some 120 kilometers (75 miles) and 56 kilometers (35 miles) north of Anchorage respectively.
"People in the areas of ash fall should seal windows and doors," protect electronics and minimize driving, the NWS advisory read.
The ash still posed a danger to aviation.
Alaska Airlines said in a statement it canceled its flights "as a safety precaution related to the pattern of ash at altitude created by the eruption.
"The airline is monitoring the ash pattern on a continuous basis and hopes to resume flights later when it is safe to do so."
Its planes on the ground in Anchorage have been "serviced and wrapped in protective sealant," the airline added.
The last significant blast from Mount Redoubt began in December 1989. Ash from the volcanic cloud clogged the four engines of a KLM airlines Boeing 747 that was flying by.
The plane plummeted more than 3,000 meters (10,000 feet) before the pilot managed to restart the engines, land the plane in Anchorage and save all 231 passengers.
Augustine volcano, situated on an isolated island in Cook Bay on which Anchorage is nestled, erupted in January 2006 without causing any damage or casualties.
Officials at Elmendorf Air Force Base in Anchorage said they were coordinating their response with local authorities.
"We've taken prudent precautions and have sheltered some aircraft, but our mission continues," said 3rd Wing commander Colonel Thomas Bergeson in a statement.
Elmendorf is home to some 60 aircraft, including F-22 Raptors -- the most advanced fighter jets in the US arsenal -- and F-15 fighter jets.
www.terradaily.com
