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While above-ground active volcanoes in the Antarctica are nothing new, finding one that is buried deep inside its thick ice layer is certainly a first. The exciting discovery was revealed in the November issue of Nature Geoscience by researchers from the Washington University in St. Louis, who stumbled upon the frozen continent's well-kept secret, accidentally.
In 2010, PhD students Amanda Lough and Andrew Lloyd led a group through the frozen continent's treacherous icy terrain to place seismometers across Marie Byrd Land in West Antarctica. Their research project dubbed POLENET was not intended to seek out volcanic or earthquake activity, but to try reconstruct Antarctica's climate history, for which they needed to first research the structure of the earth's mantle - the layer that lies between the crust and the outer core.
But those plans changed when the seismometers recorded two earthquake swarms - one in January 2010 and the other in March 2011. Recorded at depths of about 15-25 miles under the earth's surface, the tremors, which measured only 0.8 and 2.1 in magnitude, were close to the boundary between the crust and mantle and therefore, much deeper than normal earthquakes. Referred to as Deep Long Period earthquakes or DLP's, they have previously been observed near active volcanic areas in Alaska and Washington.
While scientists are not completely sure of why DLP's occur, Amanda Lough theorized that they may be the result of movement of magma and other fluids which create pressure induced vibrations in cracks within the volcanic system. These register on seismometers as 'earthquakes'.
In order to verify Amanda's suspicions, the team narrowed down the area where the seismic activity had been recorded. Sure enough, both the earthquake swarms had emanated from a small area near a series of subaerial volcanic mountains known as the Executive Committee Range. What was even more interesting is that the 'earthquakes' had occurred close to the youngest mountains in the range. But given that the tremors had been weak and of very low frequency, the team knew that they were not caused by tectonic activity. This helped further solidify their suspicions of the existence of an active volcano under the ice.
In order to investigate further, they used airborne radar to create topographic maps of the bedrock. This is when they discovered a layer of ash laying in the ice at about a depth of 1.4 km, right in the vicinity where the most recent seismic swarms had been recorded. Estimated to be 8,000 years old, it helped confirm Lough's suspicion that there was indeed an active underground volcano, one that had erupted before, albeit some time ago.
Though this is the first time an active volcano has been discovered under the thick ice, Lough maintains that the volcanic complex underneath the ground has been operating and probably erupting for millions of years, without disrupting the ice layer above. Given that the ice is at least a half-mile thick, it would take an extraordinarily large eruption - one that would release a thousand times more energy than a typical volcano, to break through. Amanda believes the chances of that ever happening, are pretty slim.
What the team can envision however, is a subglacial eruption that would melt some of the ice underneath and send large amounts of water to the nearby MacAyeal Ice Stream. If that were to occur, it may hasten the ice loss mass in West Antarctica and maybe even raise sea levels slightly.
As to when an eruption will occur or even how and why these volcanoes were formed so deep underneath? For the moment, those questions must go unanswered. That's because the seismometers that recorded this volcanic system have since been moved to other locations of the continent. But the interest this discovery has spurred in the glaciological community is bound to result in further investigation - so stay tuned!
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