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Photo Credit: Seth White/POLENET
Brian Bonnett, with IRIS PASCAL, installs seismic instruments on Fallone Nunatak in West Antarctica as part of the POLENET array, which unexpectedly discovered an active volcano below the ice sheet. The project measures various earth properties below the ice, as well as its response to the unloading of ice over long and short periods of time.

Fire and ice

POLENET instruments detect subglacial active volcano in West Antarctica

Scientists funded by the National Science Foundation (NSF) External U.S. government site have observed "swarms" of seismic activity – thousands of events in the same locations, sometimes dozens in a single day – between January 2010 and March 2011, indicating current volcanic activity under the massive West Antarctic Ice Sheet (WAIS).

Previous studies using aerial radar and magnetic data detected the presence of subglacial volcanoes in West Antarctica, but without visible eruptions or seismic instruments recording data, the activity status of those systems ranged from extinct to unknown. However, as Amanda Lough External Non-U.S. government site, a doctoral candidate at Washington University in St. Louis External Non-U.S. government site, points out, "Just because we can't see ... below the ice, doesn't mean there's not something going on there."

"This [study] is saying that we have seismicity, which means [this system] is active right now," Lough said. "This is saying that the magmatic chamber is still alive; that there is magma that is moving around in the crust."

Lough published her discovery this month in Nature Geoscience along with her advisor Douglas Wiens External Non-U.S. government site, a professor of earth and planetary sciences at Washington University in St. Louis, and a team of co-authors.

The characteristics of the seismic events, including the 25- to 40-kilometer depth at which they occurred, the low frequency of the seismic waves, and the swarm-like behavior rule out glacial and tectonic sources, but are typical of deep long-period earthquakes. Deep long-period earthquakes indicate active magma moving within the Earth's crust and are most often associated with volcanic activity.

The two swarms of seismic activity were detected by instruments deployed to obtain data on the behavior of the WAIS as part of the NSF-funded POLENET External Non-U.S. government site project, a network of GPS and seismic stations located in Antarctica and Greenland. Wiens is a POLENET principal investigator. [See previous article — Network building: POLENET project in Antarctica completes GPS/seismic array.]

See complete NSF press release here External U.S. government site.

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