The initial stress is first calculated quasi-statically under various loading conditions by using 3-dimenaional finite element model with double nodes to simulate the locked Tangsban fault. Once the shear stress at the front of fault tip reaches rupture criterion, the accumulated stress is suddenly released accompanying with frictional slip along the fault plane, the new state of stress imposed during faulting is re-calculated by reducing the shearing resistance of the hypocenter with the same boundary condition. Then the stress difference before and during shock is regarded as the driving force to generate ground motion. Numerical results show that both the fault mode and the loading system play an important role on the behavior of ground motion. To cause a greater damage and a tremendous depression on the seaward side of the fault, there must be a pre-existing oblique fault and the body force should be considered in addition to the horizontal stressing
