Simulation on seismogenic environment of strong earthquakes in Sichuan-Yunnan region, China

Based on 43 Harvard CMT solutions in Yunnan region, GPS observations from 1999 to 2004 by China Crustal Movement Observatory Network, and results from SKS splitting and Pn fast wave anisotropy, we obtained the average directions of principle stress fields at different depths by average angle method. Then we further analyzed the coupling difference between geodynamic parameters in different tectonic blocks. Then we built five three-dimensional finite element models to simulate the crustal velocity field in SichuanYunnan region and stratified stress–strain fields in different tectonic blocks. In order to implement the numerical simulation, we constrained the FEA model boundaries with GPS observations, and determined the possible flow patterns at the top of upper mantle by SKS anisotropic splitting data. Based on the simulated kinematic pattern and stress–strain fields, we analyzed the geodynamic environment in the deep part of the area, and found that the difference between lateral stress fields in different tectonic blocks is the main reason why the boundaries of tectonic blocks and their neighborhood are so active areas and capable of generating strong earthquakes. Copyright © 2009 John Wiley & Sons, Ltd.