The sudden and unexpected Wenchuan earthquake occurred on the Longmen Shan Fault. The dynamic mechanisms of the event remain enigmatic although much work has been done by scientists. In order to know more about the behaviors of the Longmen Shan thrust fault, we simulate the occurrence of earthquakes on the fault by means of viscoelastic finite element method, with gravity being included in the model. The result shows that the average earthquake recurrence time on the Longmen Shan fault is very long, ∼3,257 years. Basically, the modeled coseismic displacements have characteristics of ones for a typical thrust fault. The distribution patterns of the coseismic changes of stresses and energy are consistent with ones of aftershocks, which occurred mainly in the regionwhere the coseismic changes of stresses and energy are increased, or possibly on the region where the coseismic changes of stresses and energy are not released completely. Moreover, The model results indicate that the earthquake initiated from slip on a fault plane dipping 30°–40° northwest in depth range from 15 to 20 km, and triggered slip on the high-angle segment of the fault at depths shallower than 15 km to form large earthquakes such as the Wenchuan earthquake.
On May 12th 2008, the devastating Wenchuan earthquake (Ms=8.0) struck the densely populated China's Sichuan Province (31.0°N, 103.4°E) (CENC, 2008). The earthquake occurred by slips on multiple, imbricate, high-angle (60° to 80°) reverse faults. The surface rupture is ∼240 km long with maximum vertical offset ∼9.0m and ∼4.9m right-slip. More than 80,000 people were killed, and over 370,000 people injured in the earthquake. It is the most disastrous event in China since the 1976 Tangshan earthquake, which killed more than 240,000 people.