Abstract:Based on the simulation of strong ground motion at near-field by numerical Green function method, take the seismic source with heterogeneous dislocation distribution and crustal velocity structures in 1994 Northridge earthquake as computing model, two studies are proceeded： （1） For vertical strike fault（the dip is 90°）, we simulate the strong ground motion by means of unilateral rupture and bilateral rupture, and analyze the influence on two major strong ground motion characters--the rupture directivity effect and hanging wall effect. （2） For oblique fault, （the dip is 45°）, we compute the strong ground motion of normal fault, thrust fault and strike fault with unilateral rupture mode, and analyze the influence on rupture directivity effect and hanging wall effect. The results reveal that in near field, the rupture directivity effect and hang- ing wall effect are obviously influenced by different fault properties and seismic source modes. The seismic source modes effect the ground motion peak values and vectors distribution directly. In near field, whatever vertical fault or inclined fault, the ground motion intensity ahead of rup-ture directivity is stronger than that of behind rupture directivity, which indicats that the wavefront are compressed during propagation. The hanging wall effect can be described by simulation results of inclined fault very well. The maximum values of NS component and UP component appear on hanging wall near the fault and the EW component maximum values are dissymmetry on both sides along fault. The peak values caused by thrust fault are greater than by strike fault and normal fault, the values cause by normal fault are the smallest of all.
