Study on the development of earthquake motion taking into account the stick-slip shear failure

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The purpose of this study is first to develop a nonlinear finite element method to simulate the results from experiments on stick-slip shear failure of rock masses and to investigate the near filed strong earthquake motions. We introduced the constitutive relationships obtained from the experiments into joint elements which we employed to model the fault of rock masses. Then, we performed parametric study to investigate the effect of parameters which control the constitutive relationships on the rupture propagation. By comparing the results obtained from the proposed numerical method and experiments, we found the validity of the proposed method.Second, we analyzed the fault model of which fault parameters were known by the proposed method. We investigated the relationship between stress drop and dislocation, and found that the magnitude of dislocation was more than twice of that of known value. This discrepancy seems to be due to the two dimensional modeling of three dimensional fault system. Next we investigated the relation between rupture velocities and the magnitude of shear strength, taup, minus initial stress, taui.. The rupture velocity depended on the magnitude of taup-taui. When the value of taup-taui was small, the rupture velocity was greater than the S-wave velocity, but less than the P-wave velocity.