合成地震动空间相干性的震源机制影响  

Focal mechanism on spatial coherence of synthetic ground motion

作　　者：万珂羽 孙晓丹 WAN Keyu;SUN Xiaodan(School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China;National Engineering Research Center for Geological Disaster Prevention Technology in Land Transportation,Chengdu 610031,China)

机构地区：[1]西南交通大学土木工程学院,四川成都610031 [2]陆地交通地质灾害防治技术国家工程研究中心,四川成都610031

出　　处：《自然灾害学报》2022年第1期137-146,共10页Journal of Natural Disasters

基　　金：国家自然科学基金委员会-中国地震局地震科学联合基金项目(U2039208);国家自然科学基金项目(51878578)。

摘　　要：地震动的空间相干性是构建大跨度空间结构的多点地震动输入的关键环节。但由于大震近场地震动记录的匮乏,使得研究地震动空间相干性中的震源影响较为困难。本文基于地震动合成的运动学模型,合成由不同震源机制引起的地震动场,并借助Loh模型对合成地震动场的相干系数进行拟合,分析震源机制变化对地震动空间相干性的影响规律。研究表明:合成地震动场的相干系数,随两点间距离、频率的增加而降低,与基于密集台站记录的地震动空间相干性的普遍认识相符,表明用合成的地震动场研究空间相干性是可靠的。断层走向、倾角和滑动角中,断层走向与倾角对空间相干性影响较为显著且表现出一定规律性,滑动角对相干性的影响显著且有明显规律性。The spatial coherence of ground motion is a crucial link in establishing non-uniform excitation for large-span spatial structures. However,it is challenging to study the source effect in the spatial coherence of ground motions due to the lack of near-field ground motion records of large earthquakes. In this paper,a kinematic model of ground motion is used to simulate the ground motion field arising from different focal mechanisms. The Loh coherence model is used to fit the coherence coefficient of the simulated ground motion field,and the influence of focal mechanism on the spatial coherence of ground motion is analyzed. The results show that the coherence coefficient of the synthetic ground motion field decreases with the increase of the distance and frequency,which is consistent with the general understanding obtained based on dense array records. The influence of fault strike and dip on spatial coherence is significant and has a certain regularity. The rake also have obvious influence on spatial coherence,and the influence of rake exhibits apparent regularity.

关 键 词：地震动空间差异 空间相干性 相干函数 合成地震动 震源机制 

分 类 号：P315.9[天文地球—地震学] X43[天文地球—固体地球物理学]