Ground Deformation Imagery of the 12 May 2008 Sichuan Earthquake

Abstract

The magnitude Mw = 7.8 earthquake that struck China's Sichuan region on 12 May 2008 (Figure 1a) has been imaged by the Italian Space Agency's (ASI) Constellation of Small Satellites for the Mediterranean Basin Observation (COSMO-SkyMed radar Earth observation satellites. Five images were available—two preseismic spotlight mode images and three strip-map mode images, two of which are preseismic and one of which is postseismic. We used two strip-map images (acquired 1 month prior to and 3 days after the earthquake) to generate the first ever X-band (i.e., microwave frequency domain, corresponding to about 3-centimeter wavelength) coseismic interferogram, which clearly shows part of the strong ground deformation caused by the fault dislocation. We also performed a change detection analysis of the same data that highlighted several changes in the radar response, presumably due to strong seismic damage, as far as 80 kilometers away from the epicenter.