The relation between seismic response characteristics of Longmenshan fault zone and Wenchuan earthquake

Longmenshan fault ruptured from northeast to southwest along the edge of Sichuan Basin, which is an earthquake-prone area with a few active faults, mainly including three major faults--the Mao-Wen, Beichuan-Yingxiu and Anxian-Guanxian. The 12 May 2008 Ms 8.0 Wenchuan earthquake was one of largest continental thrusting events in the world. In order to deploy the location of drilling wells and study mechanism of the Wenchuan earthquake, we targeted a program of design for seismic acquisition and processing based on previous geological and geophysical data. And we conducted a reflection seismic acquisition and received a reflection seismic profile on the fault zone after the earthquake in Wenchuan. Through special processing and analysis of these profiles, we found the rupture which caused Wenchuan earthquake, combined with the structural characteristics of this region, geophysical information and the distribution of aftershocks following the earthquake. From the analysis of the resulting profile, the causative fault of Wenchuan earthquake is not the current three major faults, but a new fault with a lager angle, which is basically the same distribution with these aftershocks after the earthquake. All of these evidence demonstrate that the Wenchuan earthquake is caused by a new rupture.