Relation Between 3-D Structure, Mechanism and Dynamic Characteristics of Earthquakes in the Northridge Area

本研究旨在探讨北岭地震序列的三维地壳结构、断层几何形态与地震动力学特征之间的关系。1994年的北岭地震发生在横向山脉下方的南倾断层上，与1971年发生在北倾断层上的圣费尔南多地震形成鲜明对比。这将研究为什么这两个断层是这样分割的（北与南），以及是什么阻止了北岭地震的破裂进一步向西延伸。由于横向山脉涉及许多在区域南北挤压应力系统下形成的活动结构，如果该系统，如果破裂延伸到许多断层段，可能会发生比北岭地震大得多的地震。这项工作还将包括调查与三维结构有关的主要余震的动态特性（波形、应力降、能量-矩比）的变化。该项目是对国家减少地震危害计划的贡献，由北岭地震紧急拨款支持。＊＊＊

9416120 Kanamori This research is to investigate the relationship between the 3-D crustal structure, the fault geometry and the dynamic characteristics of the Northridge earthquake sequence. The 1994 Northridge earthquake occurred on a south-dipping fault beneath the Transverse Ranges, in striking contrast to the 1971 San Fernando earthquake which occurred on a north-dipping fault. This will investigate why the two faults are segmented like this (north vs. south), and what prevented the rupture of the Northridge earthquake from extending further to the west. Since the Transverse Ranges involve many active structures formed under a regional north-south compressional stress system, a much larger earthquake than the Northridge earthquake could occur if the system, a much larger earthquake than the Northridge earthquake could occur if the rupture extended over many segments of faults. The work will also involve investigation of the variation of dynamic characteristics (waveform, stress drop, energy-moment ratio) of the major aftershocks in relation to the 3-D structure. This project is a contribution to the National Earthquake Hazard Reduction Program and is supported by the Northridge Earthquake Emergency Appropriation. ***