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  • Nov 22, 2014
  • Updated: 10:56am
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SCIENCE

Massive Chilean earthquake of 2010 ‘shook Antarctic ice sheet’

PUBLISHED : Monday, 11 August, 2014, 7:58pm
UPDATED : Monday, 11 August, 2014, 8:12pm
 

A monster earthquake that struck Chile in 2010 also unleashed minor "icequakes" in Antarctica nearly 4,700km to the south, scientists said.

Sensors recorded small tremors in West Antarctica within six hours of the Chilean mega-shock, providing the first evidence that the world's greatest ice sheet could be affected by distant but powerful quakes, they said.

Twelve out of 42 monitoring stations dotted across the vast region showed "clear evidence" of a spike in high-frequency seismic signals, the team reported in the journal Nature Geoscience.

The signals tallied with signs of ice fractures near the surface, they added.

The February 27, 2010 quake off the coast of Chile's Maule region was magnitude 8.8, making it one of the largest ever recorded.

It killed more than 500 people and inflicted an estimated US$30 billion in damage.

The main shock from the event triggered microquakes as far afield as North America as the passing shock wave triggered shallow faults.

Geologists have long wondered how the ice sheets in Greenland and Antarctica - whose underlying rock is considered seismically peaceful - would respond to gigantic but distant quakes.

Until a few years ago, there were no means to explore the idea. But some useful tools have become available thanks to the deployment of a network of sensors near and on the sheets.

The data received after the 2010 earthquake was rather sketchy, the paper said. A monitoring station in West Antarctica's Ellsworth Mountains recorded a telltale seismic signature. But signals at other stations were unclear or suggested nothing had happened.

The best bet was that the tremors came from movement within the ice sheet itself, and not from any fault in the bedrock below, said Zhigang Peng at the Georgia Institute of Technology in Atlanta.

"While we are not 100 per cent sure, we think that those seismic signals come from ice cracking within the ice sheet, likely very close to the surface," Peng said.

"The main reason is that if those seismic signals were associated with faulting beneath the ice sheet, they would be similar to earthquakes at other tectonically active regions."

Put together, the data show that these vast slabs of ice could be sensitive to large, distant quakes, the paper said.

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