Four years ago, a powerful earthquake with 8.8 magnitude occurred in central Chile and rocked six regions of the country that make up about 80 percent of Chile's population. The tremors of the mega-quake, which lasted about three minutes and is now among the largest earthquakes ever recorded by a seismograph, were felt as far away as in Córdoba, Mendoza, La Rioja and Buenos Aires in Argentina, as well as in the city of Ica in Peru.
It appears though that the effects of the mega-quake, which triggered a tsunami and damaged 370,000 homes in Chile, have reached farther. A new study found that the deadly quake also resulted in icequakes in Antarctica thousands of kilometers away.
For the new study published in the journal Nature Geoscience on Aug. 10, Zhigang Peng, from the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology in Atlanta, and colleagues gathered seismic data from 42 stations six hours before and after the deadly quake that occurred at 03:34 local time to study the impact of the mega-quake on Antarctica.
The researchers found that prior to the earthquake, no icequake was recorded but 12 stations showed records of small icequakes hours after the shaking of the ground.
"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," Peng said. "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."
Peng and colleagues believe that seismic surface waves that radiate away from the epicenter of the earthquake and passing through the ice sheets have triggered the ice quakes. The researchers also think that a crevice that opened up was a source of these small icequakes.
"Icequakes happen when glaciers calve, or when crevasses open up as they move and slide along their bed," said study researcher Jacob Walters from the Institute for Geophysics at the University of Texas. "A crevasse has its own orientation, so earthquakes coming from different directions and at different strengths may affect a crevasse differently."
The findings of the study are the first documented evidence that shows powerful but distant quakes such as the 2010 Chile earthquake can rupture ice sheets albeit the overall effect of such earthquakes on ice sheets remains unclear.