近断层速度脉冲地震动的三维有限差分模拟  

Three-Dimensional Finite-Difference Simulation of Near-fault Velocity Pulse-like Ground Motions

作　　者：罗全波 陈学良[1] 高孟潭[1] 李宗超[1] 李铁飞[1] LUO Quanbo;CHEN Xueliang;GAO Mengtan;LI Zongchao;LI Tiefei(Institute of Geophysics,China Earthquake Agency,Beijing 100081,China)

机构地区：[1]中国地震局地球物理研究所

出　　处：《地震工程学报》2019年第6期1630-1636,1678,共8页China Earthquake Engineering Journal

基　　金：国家重点研发计划(2017YFC1500205);国家自然科学基金(51978633,51678537,51278470);中国地震局地球物理研究所基本科研业务专项(DQJB19B06,DQJB19A013

摘　　要：根据台湾西部地质地貌特征和1999年集集M W7.6地震的研究成果,建立三维速度结构模型和震源模型,并采用三维有限差分法对双冬断层可能产生的近断层脉冲型地震动进行数值模拟。结果表明,方向性效应引起的双向速度脉冲集中在垂直于断层滑动分量的方向上,而滑冲效应引起的单向速度脉冲则集中在平行于断层滑动分量的方向上。受方向性效应和上盘效应的共同调制,近断层脉冲型地震动反映出不对称带状分布的特征,速度脉冲主要分布在距离断层面约10 km的范围内。凹凸体的特性影响着地震动的时空分布,由地震波场显示南投和台中处于强地震动危险区。近场脉冲型地震动的研究对分析速度脉冲形成机理以及地震危险性有一定的参考意义。In this paper,based on the geological and geomorphological characteristics of western Taiwan and the results of the 1999 M W 7.6 Chi-Chi earthquake,we established a 3D velocity structure model and source model to simulate the near-fault pulse-like ground motion generated by the Shuantung fault using the 3D finite-difference method.Results showed that the double-sided velocity pulses caused by the directivity effect were mainly concentrated perpendicular to the fault sliding component,while the single-sided velocity pulses caused by the fling-step effect were concentrated parallel to this component.Due to mutual modulation of the directivity and the hanging wall effects,the near-fault pulse-like ground motions reflected an asymmetrical zonal distribution,and the velocity pulses were mostly distributed within a range of about 10 km from the fault plane.Characteristics of the asperities influenced the temporal and spatial distribution of the ground motions,and the seismic wave field showed that Nantou and Taichung are in the risk region for strong ground motion.The study of near-fault pulse-like ground motion has significance for analyzing the mechanism of velocity pulse,earthquake prevention and disaster reduction,and seismic hazard.

关 键 词：双冬断层 脉冲型地震动 数值模拟 方向性效应 滑冲效应 上盘效应 地震危险性 

分 类 号：P315[天文地球—地震学]