Antarctic Ice Was Moved by 2010 Earthquake in Chile

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Seismic events are common in Antarctica, where ice deformation causes hundreds of micro-earthquake strikes hourly, but the region's ice sheets vibrated differently after the 8.8-magnitude quake that hit Chile in 2010.

New research out of Georgia Institute of Technology, and published in the journal Nature Geoscience, is the first to document that the frozen ground of Antarctica's is sensitive to seismic waves from far away.

Researchers reviewed seismic data from 42 monitoring stations generated in the hours before and after the 3:34 a.m. shaker, which lasted about three minutes, led to the deaths of 525 people, caused a tsunami that devastated several coastal Chilean communities and ranked as the sixth largest earthquake ever to be recorded by a seismograph.

For the recent study, the scientific team used same technology used to detect the long-distance seismic effects of the devastating magnitude-9 earthquake in Japan, as it rumbled across the earth in 2011. In other words, researchers were able to single out the longer-period signals made by the earthquakes in Japan and then in Chile from higher-frequency created by nearer sources.

The analysis revealed 30 percent, or 12 of the 42 stations operating during the event in Chile showed clear evidence of the occurrence of high-frequency seismic signals, which appeared to be triggered as the quake-generated surface wave reached Antarctica.

"We interpret these events as small icequakes, most of which were triggered during or immediately after the passing," of the long-period waves "generated from the Chilean main shock," study lead Zhigang Peng, an associate professor in the School of Earth and Atmospheric Sciences," noted in a news release. "This is somewhat different from the micro-earthquakes...that traditionally occur in other tectonically active regions thousands of miles from large earthquakes.

Some of the icequakes were quick bursts and over in less than one second. Others were long duration, tremor-like signals up to 10 seconds. They occurred in various parts of the continent, including seismic stations along the coast and near the South Pole.

"Such differences may be subtle, but they tell us that the mechanisms of these triggered icequakes and small earthquakes are different," Peng said. "One is more like cracking, while the other is like a shear slip event...but at least some of the icequakes themselves create surface waves, so they are probably formed very close to the ice surface.