Study on the generation of earthquake motions considering fault rupture process

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In this study, we performed parametric analyses to examine fault rupture mechanism and strong earthquake motions on and near a fault by using three dimensional (3D) finite element method. First, we examined the effect of the length of the fault on the rupture propagation process, magnitude of the dislocation on the fault plane, and generated earthquake motions. Then, the comparison between the results from 3D analyses and those from2D analyses was made. The main results were as follows;(1) The rupture propagates in the direction of the initial shear stress at fast, and then the rupture front I gradually extends in the shape of a concentric circle.(2) The average magnitude of dislocation becomes large and approaches to a 2D result as the fault length becomes long. The relationship between the dislocation obtained from the 3D analyses and those from the 2D ones was expressed as a function of the ratio of the length of the fault and the width of it.(3) In the comparison of wave forms, the … More amplitude and the phase of the waves from 3D analyses and from D ones correspond well when the observation point is just on the fault, but the difference between them becomes increases when the distance from the fault becomes large.Next, we simulated the fault rupture process and acceleration records of the 2000 Tottoriken-seibu earthquake which occurred on October 6, 2000 by 3-D FEM. We analyzed two cases, I.e., Case1, the distribution of the stress drop on the fault was constant, Case2, the distribution was similar to that one which was obtained by the inversion analysis. The rupture process and magnitude of the dislocation were examined and simulated accelerations were compared with recorded ones. We found that the dislocation was reproducible but that it was necessary to consider ground condition, nonlinear characteristics of sail, etc. to simulate acceleration records.Third, we developed a preprocessor and a post processor for the 3D simulation and constructed on-line simulator acing nonlinear 3D finite element method. By virtue of the system turn-around time to generate dataset for the analysis and processing and drawing the obtained data was grammatically reduce. Less