Three-dimensional numerical simulation on the coseismic deformation of the 2008 M_S8.0 Wenchuan earthquake in China

Based on the finite element numerical algorithm, the coseismic displacements of the Wenchuan M_S8.0 earthquake are calculated with the rupture slip vectors derived by Ji and Hayes as well as Nishimura and Yaji. Except in a narrow strip around the rupture zone, the coseismic displacements are consistent with those from GPS observation and InSAR interpretation. Numerical results show that rupture slip vectors and elastic properties have profound influences on the surface coseismic deformation. Results from models with different elastic parameters indicate that: ① in homogeneous elastic medium, the surface displacements are weakly dependent on Poissonos ratio and independent of the elastic modulus; ② in horizontally homogeneous medium with a weak zone at its middle, the thickness of the weak zone plays a significant role on calculating the surface displacements; ③ in horizontally and vertically heterogeneous medium, the surface displacements depend on both Poissonos ratio and elastic modulus. Calculations of coseismic deformation should take account of the spatial variation of the elastic properties. The misfit of the numerical results with that from the GPS observations in the narrow strip around the rupture zone suggests that a much more complicated rupture model of the Wenchuan earthquake needs to be established in future study.