Tuesday, November 19, 2013

Volcano discovered smoldering under a kilometer of ice in West Antarctica

Washington University in St. Louis Newsroom: It wasn’t what they were looking for — but that only made the discovery all the more exciting. In January 2010, a team of scientists had set up two crossing lines of seismographs across Marie Byrd Land in West Antarctica....

...There were big questions to be asked and answered. The goal, said Doug Wiens, PhD, was essentially to weigh the ice sheet to help reconstruct Antarctica’s climate history. (Wiens is a professor of earth and planetary sciences in Arts & Sciences at Washington University in St. Louis and one of the project’s principal investigators.) But to do this accurately, the scientists had to know how the earth’s mantle would respond to an ice burden, and that depended on whether it was hot and fluid or cool and viscous. The seismic data would allow them to map the mantle’s properties.

In the meantime, automated-event-detection software was put to work to comb the data for anything unusual. When it found two bursts of seismic events between January 2010 and March 2011, Wiens’ PhD student Amanda Lough looked more closely to see what was rattling the continent’s bones.... Uncertain at first, the more Lough and her colleagues looked, the more convinced they became that a new volcano was forming a kilometer beneath the ice.

...A colleague suggested that the event waveforms looked like Deep Long Period earthquakes, or DPLs, which occur in volcanic areas, have the same frequency characteristics and are as deep. “Everything matches up,” Lough said.

...Will the new volcano erupt?  “Definitely,” Lough said. “In fact, because the radar shows a mountain beneath the ice, I think it has erupted in the past, before the rumblings we recorded.”

... On the other hand, a subglacial eruption and the accompanying heat flow will melt a lot of ice. “The volcano will create millions of gallons of water beneath the ice — many lakes full,” Wiens said.  This water will rush beneath the ice toward the sea and feed into the hydrological catchment of the MacAyeal Ice Stream, one of several major ice streams draining ice from Marie Byrd Land into the Ross Ice Shelf. By lubricating the bedrock, it will speed the flow of the overlying ice, perhaps increasing the rate of ice-mass loss in West Antarctica....

Melt water from the new volcano will drain into the MacAyeal Ice Stream, labeled above as ice stream E, its original designation. This radar image of West Antarctica (see box on the inset at bottom right for location) has been color-coded to indicate the speed at which the ice is moving. Red marks the fast-moving centers of the ice streams and black lines outline each stream’s catchment area. By greasing the skids with water, the new volcano might increase the rate of ice loss from the MacAyeal Ice Stream. From the Earth Observatory/NASA

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