Numerical simulation of dynamic process of the Tangshan earthquake

In this paper. :LDDA (Lagrangian Discontinuous Deformation Analysis) method is used in modeling thedynamic process of the M,=7.8 Tang shan earthquake on July 28, 1976 and obtain directly the dynamic and quasi static dislocations. shear stress drops, fracture velocities of the Tang shan earthquake fault. The simulation showsthai the slip history at each point of the fault is different. The displacement vectors at the concave side of the faultis greater than that of the convex side of the fault. The "over shoot" of the fault slip is greatest at the middle part ofthe fault and attenuates to its ends. The rupture velocities of the fault from the epicenter towards south-west andtowards north-east are 3.08 m/s and 1. 18 m/s, respectively, the average one is 2.13 In/s. The maximum dynamic.m quasi-static dislocations are 7. 1 m and 6.2 m respectively. the average quasi-static one on the fault is 4.5 m.initial stress dynamic and quasi-static shear stress drops are 8.1 M Pa and 5.4 MP4 respectively, the averagequasi-static shear stress drop is 3.9 M Pa. We found that the rupture velocities and shear stress are related to theinitial stress states of the fault.