Subglacial volcano melting Antarctic Ice Sheet
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|9 November 07|
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Massive subglacial volcano exploded
21 Jan 08 - A powerful volcano erupted under the West Antarctic ice
sheet around 2,000 years ago and might still be active today, say
scientists from The British Antarctic Survey (Bas), who reported their
finding in the journal Nature Geoscience.
The finding raises the question whether this or other sub-glacial volcanoes may have melted so much ice that global sea levels were affected.
The explosive event -- rated "severe" to "cataclysmic" on an international scale of volcanic force -- punched a massive breach in the ice sheet and spat out a plume some 12,000 metres (eight miles) into the sky, they calculate.
"The ash and the sulphuric acid and so on would have been blasted out mixed up with steam from the melting ice," said David Vaughan of Bas, who worked on the project.
But volcanoes which are not conspicuously active at present may also be generating heat under the ice.
Most of Antarctica is seismically stable. But its western part lies (the part where the ice is melting today) on a rift in Earth's crust that gives rise to occasional volcanism and geothermal heat, occurring on the Antarctic coastal margins.
The Hudson Mountains where the volcano was discovered lie close to Pine Island Glacier, one of the West Antarctic glaciers whose flow has accelerated in recent years. "This one is probably producing heat and melt water," said Professor Vaughan. "That would end up under Pine Island Glacier and could be thinning it."
"The flow of this glacier towards the coast has speeded up in recent decades, and it may be possible that heat from the volcano has caused some of that acceleration," Vaughan said.
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