Fault Geometry based on Coseismic Ground Displacements from Satellite Images for the 2008 Wenchuan Earthquake, Sichuan, China

On 12th May 2008, a Mw 7.9 earthquake occurred on the Longmenshan fault in the mountains to the west of Sichuan province, which shook many Asian cities and killed at least 69,000 people. The surface ruptures strike NE and extend up to 270 km along the boundary between the eastern Tibetan Plateau and the Sichuan basin. It was difficult to complete the detailed mapping of surface ruptures and to measure fault slip in the field because well-defined features to correlate across the fault were rare in mountainous area. Near surface deformation is in fact composed of contributions from internal faulting and folding. Using the COSI-Corr software, we obtain coseismic ground displacements deduced from sub-pixel correlation of SPOT5 and ENVISAT and also from D-InSAR on ENVISAT. The results can provide continuous surface displacements. In the south, the results show significant shortening, generally <10 meters, and two parallel ruptures, while in the north, they show strike slip dominant and only a single rupture. Based on our results, we simulate the fault geometry in different locations. To realize the long-term fault kinematics a comparison is further needed between coseismic deformation and long-term geomorphic deformation recorded in the landforms.