AGU: Geophysical Research Letters

 

Editors' Highlight

Satellite gravity measurements detect deformation from Sumatra-Andaman earthquakes

Satellite gravity measurements, which have been used to estimate changes in groundwater storage, sea level, and polar ice sheet extent, can also provide a unique way to monitor deformation associated with major earthquakes, supplementing Global Positioning System measurements, which are limited if earthquakes happen offshore. Chen et al. (2007) used data from the Gravity Recovery and Climate Experiment (GRACE) to observe and study the effects of coseismic and postseismic deformation due to the rupture from the M_w = 9.3 Sumatra-Andaman earthquake on 26 December 2004 and its companion Nias earthquake (M_w = 8.7) on 28 March 2005. Through improved filtering methods and more refined processing of GRACE data, the authors found that the gravity field disturbance caused by these earthquakes extends over 1800 km along the Andaman and Sunda subduction zones; these disturbances change with time following the earthquake. They expect that gravity changes are due to after slip, viscous relaxation of the upper mantle, or other processes associated with upper mantle recovery after such great earthquakes.

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