1989年大同一阳高震群的库仑应力相互作用研究  

Possible Coulomb Stress Interactions between the Three Main Earthquakes in the 1989 Datong-Yanggao Earthquake Swarm

作　　者：王霞[1] 宋美琴[1] 郭文峰 陈慧 方强 WANG Xia;SONG Meiqin;GUO Wenfeng;CHEN Hui;FANG Qiang(Shanxi Earthquake Agency,Taiyuan 030021,Shanxi,China;Guangshan Branch of the Xinyang Ecological Environment Bureau,Guangshan 465450,Henan,China)

机构地区：[1]山西省地震局,山西太原030021 [2]信阳市生态环境局光山分局,河南光山465450

出　　处：《地震研究》2022年第4期560-569,共10页Journal of Seismological Research

基　　金：中国地震局地震科技星火计划(XH200403Y);山西省科技厅面上青年基金(201901D211548);中国地震局地质所国家野外站研究课题(NORSTY2021-01);山西省科技攻关项目(20140313023-1);山西省应用基础研究计划(201801D121030);国家自然科学基金(41874053,42030108)联合资助。

摘　　要：通过计算1989年大同—阳高震群序列中5.7、5.9、5.6级3次地震的同震静态库仑应力,分析不同断层参数对库仑破裂应力的影响,并结合震群序列的分布和扩展方式,定量研究3次地震之间的触发关系。结果显示:5.7级地震可能是NW向左旋走滑,之后5.9级地震发生右旋走滑,震群活动为一组共轭剪切破裂的结果,并触发了后续地震。综合分析3次地震的时空分布与库仑应力变化的关系,推测1989年大同—阳高震群可能的发震机制为:(1)在区域应力场增强的背景下,2条共轭的发震断层均接近破裂临界水平,屈服应力较低的NW向团堡断裂先发生破裂;(2)随后触发NE向大王村断裂破裂,且以NE向破裂为主,这与区域应力场方向一致;(3)研究区域接收断层的有效摩擦系数比较高,在0.4以上;(4)5.9级地震的发生,触发了西南区域的地震序列,东南区域的地震序列可能受5.9级地震的影响,并受控于断层的摩擦系数。总体而言,这3次M>5.5地震之间存在着一定的触发关系,5.9级地震对周边断层有明显的触发作用。We calculated the co-seismic static Coulomb stress changes of the M5.7 earthquake,the M5.9 earthquake and the M5.6 earthquake in the 1989 Datong-Yanggao earthquake swarm,and analyzed the effects of different fault parameters on the Coulomb stress field,and quantitatively investigated the triggering relationships among these earthquakes by combining the distribution patterns of the aftershock sequences.The results show that the M5.7 shock may have been characterized by NW left-lateral strike-slip,followed by NE right-lateral strike-slip of the M5.9 shock,with conjugate activity of the seismogenic fault,and triggered the subsequent aftershocks.A comprehensive analysis of the distribution of events and the Coulomb stress changes suggests that the possible seismogenic mechanisms of the 1989 Datong-Yanggao earthquake swarm are:(1)In the context of the enhanced regional stress field,the 2 conjugate seismogenic faults were both close to the critical state of failure,and the NW-oriented Tuanbao fault ruptured firstly with lower yield stress;(2)The NE-oriented Dawangcun fault was subsequently triggered rupture,and the NE-oriented rupture was predominant.The main aftershocks were distributed in NE direction,which was consistent with the direction of the NE principle compressive stress;(3)The effective friction coefficients of the receiving faults in the study area were relatively high(over 0.4);(4)The M5.9 earthquake triggered the aftershocks in the southwest region,and the aftershocks in the southeast region may be influenced by the M5.9 earthquake,and was controlled by the friction coefficient of the fault.Generally,there was a trigger relationship between the three M>5.5 earthquakes,and the M5.9 shock had a significant triggering effect on the surrounding faults.

关 键 词：库仑应力 应力触发 有效摩擦系数 大同—阳高震群 

分 类 号：P315.24[天文地球—地震学]