سال انتشار: ۱۳۸۲
محل انتشار: چهارمین کنفرانس بین المللی زلزله شناسی و مهندسی زلزله
تعداد صفحات: ۸
M. R. Ghayamghamian – Assistant Professor, Geotechnical Earthquake Eng. Dept., IIEES, P.O. Box 19395- 3913 Tehran, Iran
In engineering practice, the near-field ground motions are estimated assuming that the fault main parameters, such as slip time function, slip velocity, stress drop etc, are constant on the fault.However, the generation of high-frequency near-field motions indicates that the source function is complex, which is due to the heterogeneity of the slip and slip velocity on the fault plane. In addition, recent waveform inversion of rupture process using earthquake data clearly revealed that the near-field ground motions are strongly influenced by the inhomogeneous faulting procedure at the source. Thus, to adequately estimate the near-field ground motions, it is necessary to characterize the inhomogeneous faulting parameters at the source. To this end, the slip and slip velocity distribution in the source area as well as the average slip on the fault plane should be known. While, in practice, it is hardly possible to determine such parameters in details. Therefore, it is an important task to estimate near-field ground motion characteristics during heterogeneous rupture propagation.Here, the characteristics of near-field ground motion are investigated taking into account slip heterogeneity on the fault plane. The area with slip values larger than average slip, which is called “asperities”, is defined on the fault. The effects of asperities on the near-field ground motions are numerically examined for different size and location of asperities on the fault. To this end, the nearfield velocity ground motions are simulated using ramp type source-function and heoretical Green’s function. The asperities generate a pulse-shape velocity ground motion that its amplitude and period found to have a proportional relationship with the size and location of the asperities on the fault. Furthermore, the variation of response spectrum with the asperities specifications on the fault is also investigated.