Coseismic gravity changes of the 2010 earthquake in central Chile from satellite gravimetry

[1] The first map of coseismic changes in gravity and geoid height has been drawn using the data from the Gravity Recovery and Climate Experiment (GRACE) satellites for the 2004 Sumatra-Andaman earthquake. Here we present the second case of coseismic gravity change observation by satellite gravimetry, i.e., the change caused by an interplate thrust earthquake that occurred on 27 February, 2010 in Central Chile (Mw = 8.8). Gravity showed a negative jump with the largest drop of ∼5 μgal on the back-arc side. The observed changes agree with those calculated assuming the realistic earth and fault parameters inferred from coseismic displacements of Global Positioning System (GPS) stations. Gravity in this area shows large seasonal and inter-annual variability, and postseismic gravity changes could be isolated only by carefully removing hydrological signals.

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