for National Geographic News
A rare volcanic eruption punched through Antarctica's ice sheet more than 2,000 years ago, scattering ash across the frozen landscape, a radar survey has revealed.
The eruption was the biggest in Antarctica in the past 10,000 years, researchers estimate.
The volcano's continuous output of heat may still be melting the base of the ice sheet, and could be partially responsible for the fast flow of a nearby glacier.
David Vaughan and Hugh Corr of the British Antarctic Survey, based in Cambridge, England, spotted signs of the eruption using ice-penetrating radar, which revealed a layer of volcanic rock embedded within the ice sheet.
"There would have been a very big bang as the plume of ash and steam broke through the ice," Vaughan said. "Then ash would have begun to rain down on to the ice surface."
As snow fell over the centuries, this ash layer got buried, and is now embedded in the middle of the ice sheet.
Other studies have found indirect evidence of volcanoes under Antarctica, and researchers have tracked volcanoes erupting under the ice in Iceland.
(Related: "Ancient Egypt Cities Leveled by Massive Volcano, Lava Find Suggests" [April 2, 2007].)
But the new study is the first to show direct evidence of a relatively recent eruption from under the Antarctic ice sheet—one that could still be affecting the ice sheet today.
The study appeared January 20 in the journal Nature Geoscience.
The distinct layer of ash within the ice was "stunning," Vaughan said: The scientists had never seen anything like it.
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