Active Volcano Discovered Underneath Antarctic Ice Sheet
Earthquakes deep below West Antarctica reveal an active volcano hidden beneath the massive ice sheet, researchers said today (Nov. 17) in a study published in the journal Nature Geoscience.
The discovery finally confirms long-held suspicions of volcanic activity concealed by the vast West Antarctic Ice Sheet. Several volcanoes poke up along the Antarctic coast and its offshore islands, such as Mount Erebus, but this is the first time anyone has caught magma in action far from the coast.
"This is really the golden age of discovery of the Antarctic continent," said Richard Aster, a co-author of the study and a seismologist at Colorado State University. "I think there's no question that there are more volcanic surprises beneath the ice."
The volcano was a lucky find. The research project, called POLENET, was intended to reveal the structure of Earth's mantle, the layer beneath the crust. In 2010, a team led by scientists from Washington University in St. Louis spent weeks slogging across the snow, pulling sleds laden with earthquake-monitoring equipment. [Images: Trek Across Antarctica]
Right place, right time
Two earthquake swarms struck beneath the researchers' feet in January 2010 and March 2011, near the Executive Committee Range in the Marie Byrd Land region of the continent. As the researchers later discovered, the tremors — called deep, long-period earthquakes (DLPs) — were nearly identical to DLPs detected under active volcanoes in Alaska and Washington. The swarms were 15 to 25 miles (25 to 40 kilometers) below the surface.
"It's an exciting story," said Amanda Lough, the study's lead author and a graduate student in seismology at Washington University in St. Louis. Though there were no signs of a blast, a 3,200-foot-tall (1,000 meters) bulge under the ice suggests the volcano had blasted out lava in the past, forming a budding peak...
"We can say with pretty high confidence that there wasn't an eruption while we were out there," Lough told LiveScience's OurAmazingPlanet. "We had people installing [seismometer] stations and flying airborne radar over the ice. But from the bed topography, we can see there is something building up beneath the ice."
Scientists think that underground magma and fluids pushing open new paths and fracturing rock cause deep, long-period earthquakes. Many active volcanoes in Alaska's Aleutian Islands have frequently produced these deep earthquake swarms without any signs of impending eruptions. However, researchers also monitor the tremors because a sudden uptick in shaking was seen before eruptions at Mount Spurr and Mount Redoubt in Alaska.
A volcanic flood
If the volcano in Antarctica did erupt, it would melt the bottom of the ice sheet immediately above the vent. Scientists aren't sure what would happen next. In Iceland, volcanic eruptions can melt glaciers, causing massive floods calledjökulhlaups. But the ice above the Antarctic volcano is more than a half-mile (1 km) thick.
"How West Antarctic ice streams would react to an eruption a hundred or more kilometers [60 miles] inland from the grounding line is a yet-to-be-answered question," said Stefan Vogel, a glaciologist with Australian Antarctic Division who was not involved in the study. The grounding line is the spot where glaciers detach from rock and float on water...
