Icequakes in Antarctica Caused by 2010 Chilean Earthquake: Ice Rattled by Event

Icequakes can shake Antarctica, trembling across the frozen desert in the form of hundreds of micro-eqrthquakes an hour due to ice deformation. But in March 2010, Antarctica experienced more of an icequake than usual due to the Chilean earthquake. The kicker is that this earthquake occurred 3,000 miles away.

Yet what were the effects of the Chilean earthquake on Antarctica? That's exactly what scientists wanted to find out. They looked at seismic data from 42 stations in the six hours before and after the earthquake. They then removed longer-period signals as the seismic waves spread from the distant epicenter in order to identify high-frequency signals from nearby sources.

"We interpret these events as small icequakes, most of which were triggered during or immediately after the passing of long-period Rayleigh waves generated from the Chilean mainshock," said Zhigang Peng, one of the researchers, in a news release. "This is somewhat different from the micro-earthquakes and tremor caused by both Love and Rayleigh-type surface waves that traditionally occur in other tectonically active regions thousands of miles from large earthquakes."

The newly-found icequakes responded to volumetric deformation. That's a stark contrast to micro-earthquakes, which respond to both shearing and volumetric deformation.

"Such differences may be subtle, but they tell us that the mechanism of these triggered icequakes and small earthquakes are different," said Peng. "One is more like cracking, while the other is like a shear slip event. It's similar to two hands passing each other."

The scientists found that some of the icequakes created surface waves, which indicated that the source of the quakes was very near to the surface. In addition, the ressearchers suspect that the quakes simply reflect fracturing of ice in the near surface due to alternative volumetric compressions and expansions as the Rayleigh waves passed through the ice.

The findings reveal a bit more about how even distant earthquakes can impact locations thousands of miles away. This, in turn, shows that earthquakes have far more consequences than just in the area where they originated from.

The findings are published in the journal Nature Geoscience.