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Thousands of tiny quakes shake Antarctic ice at night

Stay overnight on an Antarctic ice shelf, and you may feel the shaking from thousands of tiny quakes as the ice re-forms after melting during the day. In a recent study, National Science Foundation-funded scientists placed seismometers on the McMurdo Ice Shelf and recorded hundreds of thousands of tiny "ice quakes" that appear to be caused by pools of partially melted ice expanding and freezing at night. The phenomenon may be able to help scientists track glacier melting -- and to help explain the breakup of large ice shelves. Climate change is causing the Antarctic to melt, but glaciologists are still mapping how, where and why. There is much we still don't understand about the process -- as evidenced by the massive Larsen B ice shelf collapse in 2002, which took glaciologists by surprise -- and understanding these mechanisms is key to predicting the future for the ice. The team set up seismometers for 60 days during the melt season in two locations near seasonal meltwater lakes on the McMurdo Ice Shelf. One was drier; the other was slushier, with pools of melted water forming and refreezing. The wetter location, they found, was alive with seismic activity at night.

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