2021年云南漾濞MS6.4地震动态应力对后续余震活动的触发作用  

Impact of dynamic stress on aftershock triggering of the 2021 Yunnan Yangbi MS6.4 earthquake

作　　者：刘容 陈强 杨莹辉 钟霞 苑雨 Liu Rong;Chen Qiang;Yang Yinghui;Zhong Xia;Yuan Yu(Faculty of Geosciences and Environmental Engineering,Southwest Jiaotong University,Chengdu 611756,China;State Key Laboratory of Geohazard Prevention and Geoenvironment Protection,Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]西南交通大学地球科学与环境工程学院,中国成都611756 [2]成都理工大学地质灾害防治与地质环境保护国家重点实验室,中国成都610059

出　　处：《地震学报》2023年第1期17-28,共12页Acta Seismologica Sinica

摘　　要：选取IRIS远震台站波形数据,反演了云南漾濞MS6.4地震震源破裂过程,计算了断层破裂在近场产生的动态库仑破裂应力变化,并讨论了主震对近场余震活动的动态应力触发作用。结果显示:动态库仑应力演化过程与震源破裂特征反演结果一致,其大小分布与地震序列分布的疏密程度也具有较好的相关性。主震产生的静态和动态库仑破裂应力均促进余震的发生,但相比静态应力,余震位于库仑破裂应力正值区域的比例提高了21%,余震与动态库仑应力变化的正负区域有更好的一致性,动态应力能更好地解释震后余震分布的空间特征。垂直于地震序列主干10 km处出现小震丛集,该现象可能是由主震产生的动态库仑破裂应力占主导作用所致。定量分析主震对余震的动态应力触发结果显示,主震后一周内MS4.0以上的8次余震接收点均受到了动态库仑破裂应力的触发作用。Based on the waveform data of IRIS teleseismic station,this paper inversed the focal rupture process of Yunnan Yangbi MS6.4 earthquake,calculated the dynamic Coulomb rupture stress change caused by fault rupture in near field and discussed the dynamic stress triggering effect of main shock on near-field aftershock activity. The results show that the evolution process of dynamic Coulomb stress is consistent with the inversion results of source fracture characteristics,and its size distribution is also well correlated with the density of seismic sequence distribution. The static and dynamic Coulomb rupture stress produced by the main shock promote the occurrence of aftershocks,but compared with the static stress,the proportion of aftershocks located in the positive Coulomb rupture stress area is increased by 21%,and the positive and negative areas of aftershocks and dynamic Coulomb stress change have better consistency. The dynamic stress can better explain the spatial characteristics of aftershocks distribution after the earthquake. Small earthquakes cluster at 10 km perpendicular to the main trunk of the earthquake sequence,which may be caused by the dominant dynamic Coulomb fracture stress produced by the main earthquake. Quantitative analysis of the dynamic stress triggering of the main shock to the aftershock shows that within one week after the main shock,eight aftershocks receiving points bigger than MS4.0 are triggered by the dynamic Coulomb rupture stress.

关 键 词：云南MS6.4地震 地震破裂过程 动态库仑破裂应力 应力触发 

分 类 号：P315.33[天文地球—地震学] P315.727[天文地球—固体地球物理学]