The finding, detailed in the current issue of Nature Geoscience, marks the first time that an active volcano has been discovered under the ice of the frozen continent. (Also see "Giant Undersea Volcanoes Found Off Antarctica.")
When it erupts—which no one can predict—the volcano "will create millions of gallons of water beneath the ice—many lakes full," study leader Doug Wiens, professor of earth and planetary science at Washington University in St. Louis, said in a statement.
This water will rush beneath the ice toward the sea and feed into one of the major ice streams that drain ice from Antarctica into the Ross Ice Shelf, Wiens explained.
The new volcano's discovery was accidental. In January 2010, scientists set up a series of seismometers, or earthquake detectors, on Marie Byrd Land, a highland region of West Antarctica.
The instruments array detected two swarms of earthquakes about one year apart, in 2010 and 2011. The earthquakes were small, with magnitudes of between 0.8 and 2.1.
The tremors occurred at depths of about 15 to 25 miles (25 to 40 kilometers), close to the boundary between the crust and the mantle, and much deeper than normal crustal earthquakes.
The depth at which the quakes occurred, as well as their low frequency, suggests they might be so-called Deep Long Period earthquakes, or DPLs, which occur in volcanic areas.
"People aren't really sure what causes DPLs," said Amanda Lough, a postdoctoral student in Wiens's lab and the first author of the study, said in a statement.
"It seems to vary by volcanic complex, but most people think it's the movement of magma and other fluids that leads to pressure-induced vibrations in cracks within volcanic and hydrothermal systems."
Why is the discovery important?
Lough and her team say it's not a matter of if the newly discovered volcano will erupt, but when. "It most likely has erupted before," Lough said. (Watch video: Volcanoes 101.)
That's because the volcano sits atop a raised portion of land that the team believes is composed of previously erupted material.
What would happen in an eruption?
The volcano is covered by more than half a mile (one kilometer) of ice, so it would have to be an extraordinarily powerful eruption to breach the surface.
However, the heat from the volcano could increase melting at the base of the glacier and meltwater could act like a lubricant that makes the overlying ice flow out to sea faster. Global sea levels could rise by a small amount as a result.
"We're not talking about an eruption causing the ice sheet to melt and cause catastrophic sea-level rise," Lough told National Geographic.
"This volcanic complex has been operating for millions of years ... There have been past eruptions of this system and the ice has survived for millions of years, [so] future eruptions alone will not cause the ice sheet to fail."
Most of the seismometers used to discover the volcano have been removed and installed in other areas in Antarctica, so further study of its seismic activity is no longer possible.
But Lough said she hopes scientists will continue to study the volcano using other instruments.
"I'm really excited because this paper has stirred up a lot of interest in the glaciology community," she said, "and hopefully someone there will take up the challenge to answer the questions of what are the possible outcomes."
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