Numerical Simulation on Influences of Wenchuan Earthquake on the Stability of Faults in the Neighborhood
LI Yu-jiang, CHEN Lian-wang, LU Yuan-zhong, ZHAN Zi-min Key Laboratory of Crustal Dynamics, Institute of Crustal Dynamics, CEA, Beijing 100085, China
When a major earthquake occurred, it's critical to analyze the influences on the surrounding faults and the potential seismic activity. In this paper, a complex viscoelastic model of western Sichuan and eastern Tibet regions is constructed including the topography, and then we find out the Coulomb failure stressing rate on these major faults and calculate the stress change caused by the Wenchuan earthquake taking the post-seismic relaxation into consideration. Our preliminary results indicate that: (1) the Coulomb stressing rate in the Longmen Shan fault is lower with values from 0.28×10-3 MPa/a to 0.35×10-3 MPa/a, which is consistent with the previous long reccurrence interval of Wenchuan earthquake; (2) The Wenchuan earthquake not only caused the Coulomb failure stress decrease in the source region, but also the stress increase in the northeastern segment, and it's comparatively consistent with the aftershock distribution; (3) The Coulomb failure stress change caused by Wenchuan earthquake showed significant increase on five major fault segments, which were northwestern segment of Xianshui fault, eastern Kunlun fault, Longriba fault, Minjiang fault and Huya fault respectively, also the Coulomb failure stress on the fault plane of the Yushu earthquake was faintly increased; (4) The characteristic earthquake recurrence interval of the Xianshui fault is delayed by 52-104 a deduced from the Wenchuan earthquake, so it's ranked the high seismic hazard region in the future.