Abstract:We use the GNSS post-seismic deformation data in the Wenchuan area from 2010 to 2015, and establish a three-dimensional post-seismic viscoelastic relaxation model using the finite element method. The two-dimensional grid search is used to obtain the optimal thickness of the elastic layer and the best viscosity coefficient of the middle and lower crust. We analyze the post-seismic deformation characteristics under the influence of viscoelastic relaxation 2-7 years after the Wenchuan earthquake. The GNSS post-seismic deformation data during 2008-2009 are used as constraints to obtain the best parameters. We compare the combined model of elastic relaxation and afterslip with the afterslip model to analyze the deformation characteristics within one year of the Wenchuan earthquake. The results show that the optimal thickness of the elastic layer in the eastern part of the Tibet plateau is 25 km, the optimal viscosity coefficient of the middle and lower crust is 4.0×1018 Pa·s. The fitting effect of the combined model is better than that of the single afterslip model within one year after the earthquake, and the afterslip deformation is the main component.
LIU Zhijun,TAN Kai,WANG Qi et al. Numerical Simulation Analysis of After-Slip and Viscoelastic Relaxation after the Wenchuan Earthquake[J]. jgg, 2021, 41(6): 577-583.