【摘要】 本文以汶川地震中的非发震断层鲜水河断裂带周边石棉地区所获取的加速度记录为依据,研究了这些记录在峰值、频谱间的差异。结果表明,以鲜水河断裂带为界,近震源侧地震动强度更大且高频更丰富。对该地区区域构造特征初步分析表明,鲜水河断裂带对汶川地震产生的地震动具有隔震效应。基于显式有限元和局部透射人工边界的二维有限元断层场地模型,对该地区的地面运动模拟结果表明,入射波动所指向的一侧地面运动更小,说明较陡的断层破碎带对斜入射地震波具有一定的隔震效应。更多还原

【Abstract】 In this study, we analyzed the peak ground acceleration( PGA) and spectral characteristics of the earthquake acceleration records from the main shock of Wenchuan earthquake,the difference of the ground motion at both sides of the Xianshuihe fault zone. We found anomalously large amplitude and extremely rich high frequency in the ground motion near source side(right side of the fault in this case).Our results indicate that the non-causative fault(Xianshuihe fault zone)can obstruct the spread of seismic wave,and the isolation effect of the non-causative fault is presented. Numerical solution of 2-D model of this fault site derived by the explicit finite element combining with local multi-transmitting artificial boundary method is used for interpreting the mechanism of difference of the ground motion. The study of 2-D vertical low velocity fault zone( LVFZ) model struck by external oblique incidence seismic radiation shows that vertical LVFZ can obstruct the spread of oblique incidence seismic wave.更多还原