Re: Volcano erupts in Indonesia, forcing thousands to flee
Eruption
As the Indonesian volcano explodes, scientists fear something far more catastrophic may be brewing
William Sargent
Boston Globe
THE MERAPI volcano, currently exploding more forcefully every day in Indonesia, is located on the Sundra Arc, one of the planet’s most complex and dangerous geological areas. This is where two large plates of the earth’s crust, the Australian and Indian plates, are rapidly plunging down below the mini Burma plate to create the world’s deepest and most powerful earthquakes and the world’s largest and most dangerous volcanoes. Some scientists fear that something catastrophic may be brewing beneath the Sundra Arc.
The world’s three most deadly tectonic events in recorded history all occurred in this arc of volcanic islands that include Sumatra and Java. Tambora, the largest volcano ever recorded in human history, erupted in 1815. Records were not very good at the time, but at least 100,000 people died in the supervolcano.
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In 1831, the world’s second largest recorded volcano blew 4 cubic miles of material off the top of Krakatoa Mountain and into the Indian Ocean, where it created a 150-foot high tsunami that killed 34,000 people. This disaster was more fully recorded because the telegraph had just been invented.
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And then there was the tsunami that occurred the day after Christmas in 2004. It killed 150,000 people and left millions more homeless.
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The present cycle of tectonic activity probably started right around that time in 2004 when the Indian plate thrust rapidly below the Burma plate, initiating one of the deepest and most powerful earthquakes ever recorded.
The magma emerging out of Merapi is not liquid lava like what we see flowing out of Hawaiian volcanoes. This material is more like
half-melted rock that is extruded out of the volcano like toothpaste being squeezed out of a tube. But
the magma also contains gases under pressure that are causing the eruptions, rockfalls of flaming hot boulders, and pyroclastic flows: shock waves of heated gas and ash that on Nov. 5
engulfed an entire village in a “safe’’ area nine miles from the base of the volcano.
These pyroclastic flows of ash and hot gas are what seared people’s lungs on Pompeii. They can also travel unseen across half a mile of water to incinerate ships at sea as they did when Mount Pelee erupted off the island of Martinique in 1902.
But Merapi is not the only volcano now active on the Sundra Arc.
Within the past few weeks there have been many more deep earthquakes and 20 other volcanoes have also become active. Indonesia is also home to the Lake Toba supervolcano, believed to be the largest explosive eruption to have occurred on our planet during the past 25 million years.
Read more here:
http://www.boston.com/bostonglobe/editorial_opinion/oped/articles/2010/11/10/eruption/