长宁—兴文地区应力降等震源参数与区域内显著地震的时空关系  

Spatio-temporal relationship between source parameters such as stress drop and significant earthquakes in Changning-Xingwen area

作　　者：何鑫俊 张晓东[1] 孟令媛[2] 王月 He Xinjun;Zhang Xiaodong;Meng Lingyuan;Wang Yue(Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China;China Earthquake Networks Center,Beijing 100045,China)

机构地区：[1]中国地震局地震预测研究所,中国北京100036 [2]中国地震台网中心,中国北京100045

出　　处：《地震学报》2023年第2期271-284,共14页Acta Seismologica Sinica

基　　金：国家自然科学基金(41974068);中国地震科学实验场的地震可预测性国际合作研究(2018YFE0109700)共同资助。

摘　　要：基于中国地震台网提供的震相观测报告,利用双差方法对长宁—兴文地区2019—2020年1 948个M_(L)≥2.0地震事件进行了重定位,重定位后的1 823个M_(L)≥2.0地震事件分布显示长宁—兴文地区北区地震序列沿NW—SE方向背斜展布,而南区地震分布较分散。之后计算了四川长宁—兴文地区2019年6月17日至2020年12月31日208个M_(L)≥3.0地震事件的地震矩和应力降等震源参数,分析了2019年6月17日长宁MS6.0地震后研究区内地震应力降的演化特征,结果显示长宁—兴文地区中强地震发生前M_(L)3.0—3.9地震的应力降显著升高,且M_(L)≥4.0地震多发生在ML3.0—3.9地震的应力降高值区。A MS6.0 earthquake with a focal depth of 16 km occurred with the epicenter of(28.34°N,104.90°E)in Changning county,Yibin city,Sichuan Province on June 17,2019.There were three strong aftershocks above MS5.0 within five days after the Changning earth-quake and another MS5.6 earthquake occurred in Gongxian County on July 4.This paper relo-cated 1948 M_(L)≥2.0 earthquakes in Changning-Xingwen area during 2019 to 2020 by the double difference method based on the seismic phase observation report provided by China Earthquake Networks Center. The distribution of 1 823 earthquakes above M_(L)2.0 after reloca- tion shows that the aftershock sequence in the northern area of Changning spreads along the NW−SE direction anticline. Moreover,the earthquakes in southern area is more scattered. We calculated source parameters such as seismic moment and stress drop based on 208 earthquakes above M_(L)3.0 in Changning-Xingwen area,Sichuan from 17 June 2019 to 31 December 2020, and analyzed the evolution characteristics of seismic stress drop in the region before and after the Changning MS6.0 earthquake on June 17,2019. The results show that the stress drop of M_(L)3.0−3.9 earthquakes significantly increased in Changning-Xingwen area before the mode-rate strong aftershocks,and most of the earthquakes above M_(L)4.0 occurred in the high stress drop area of M_(L)3.0−3.9 earthquakes in the study area.

关 键 词：长宁M_S6.0地震 重定位 应力降 

分 类 号：P315.72[天文地球—地震学]