Volcanic Rumblings Under Antarctic Ice

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What could be more trivial and inconsequential than tiny earthquakes in the icy wastes of Antarctica? Plenty, when the quakes might be from magma moving in the crust beneath the West Antarctic Ice Sheet — a possible hint that an eruption is on the way to open the flood gates for water and ice pouring out of that vast region.

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Two deep, low-magnitude earthquake swarms recorded by a seismic network in 2010 and 2011 have been detected near what’s called Mount Sidley, but are from the ground under deep ice, according to a new report in Nature Geoscience.

“Such earthquakes occur beneath active volcanoes, are caused by deep magmatic activity and, in some cases, precede eruptions,” writes the team led by Amanda Lough of Washington University. The same sorts of pre-eruption swarms of tiny quakes were recorded at Mount Pinatubo in 1991, they said.

In this case, however, any eruption would happen under 1,400 meters (almost 4,600 feet) of ice, and probably never melt through to the surface. But that wouldn’t stop all that hot rock from melting a lot of ice and drastically increasing the melt water draining from under this gigantic basin. All that liquid water under the ice could also lubricate ice streams so they flow faster. If that was to happen, it would be a new and unwelcome addition to the worrisome problem of polar ice losses from global warming that’s already measurably raising sea levels worldwide.

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As additional evidence that the regions volcanoes are not dead, the researchers also cites ice-penetrating radar data which has spotted a plume of volcanic ash buried in the ice. The ash is thought to have come from the nearby Mount Waesche. Based on how fast ice accumulates in the area, the ash is estimated to have rained down on the ice surface about 8,000 years ago — less than the wink of an eye ago in geological terms.

So should we worry about tiny earthquakes in Antarctica? Yeah. We should.

Caption: POLENET/ANET field team drags equipment to install remote seismic and GPS stations at Mount Sidley (seen in background). (Jeremy Miner)

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