尾波干涉技术在2017年重庆武隆M_(S) 5.0地震后震源区地壳介质变化的应用  

Application of coda wave interferometry in crustal medium variation in focal area after Chongqing Wulong M_(S)5.0 earthquake in 2017

作　　者：汪建 向涯 杨亚运 李翠平 WANG Jian;XIANG Ya;YANG Yayun;LI Cuiping(Chongqing Earthquake Agency,Chongqing 400020,China;Key Laboratory of Earthquake Geodesy,Institute of Seismology,China Earthquake Administration,Wuhan 430071,China;Key Laboratory of Earthquake Geodesy,China Earthquake Administration,Wuhan 430071,China)

机构地区：[1]重庆市地震局,中国重庆400020 [2]中国地震局地震研究所,中国武汉430071 [3]中国地震局地震大地测量重点实验室,中国武汉430071

出　　处：《地震地磁观测与研究》2021年第3期64-73,共10页Seismological and Geomagnetic Observation and Research

基　　金：中国地震局监测、预报、科研三结合课题(项目编号:3JH-2021040);重庆市地震局科研项目。

摘　　要：2017年11月23日,重庆武隆发生M_(S)5.0地震,震后1个月内发生107次M_(L)≥1.0地震,双差定位结果显示,主震震源深度约10 km,破裂面呈近SW向单侧破裂。选取震中附近布设的3个流动台地震波形及观测资料记录,利用波形互相关技术,挑选武隆M_(S)5.0地震后符合条件的重复地震事件,利用尾波干涉技术,分析震源区震后地壳介质变化。结果显示:①S波早期尾波部分呈明显的线性变化,可能由震源区附近地壳介质的波速变化所引起;②由震中距最小的重复地震计算的相对波速变化最大;③在P波尾波发现走时延迟和不相关系数均存在1个短周期“尖峰”变化,可能与震后地下介质中散射体的运移有关;④震后局部地区的地震波速度存在上升—下降的恢复过程。On November 23,2017,an M_(S)5.0 earthquake occurred in Wulong,Chongqing.Within one month after the Wulong M_(S)5.0 earthquake,107 earthquakes with M_(L)≥1.0 occurred.The results of the double-difference location method show that the focal depth of the mainshock is about 10 km and the rupture is unilateral with a near SW plane.We select seismic waveform and observation data of three mobile stations located near the epicenter in the study.The waveform cross-correlation technology is used to pick out eligible repeating earthquakes after the Wulong M_(S)5.0 earthquake.The variation of crustal media in the focal area after the Wulong M_(S)5.0 earthquake is analyzed by coda interference technology.The results show that:①The linear trend of delay time in early S wave coda is very obvious,which may indicate seismic velocity variations of underground media in the focal area;②The relative wave velocity of the repeating earthquake with the minimum epicentral distance is the largest;③A short period“spikes”of travel time delay and uncorrelation coefficient are found in P wave coda,which may be related to the migration of scatters in underground media after the Wulong M_(S)5.0 earthquake;④The recovery process of seismic wave velocity rise to fall in the local area after the Wulong M_(S)5.0 earthquake is also found.

关 键 词：武隆M_(S)5.0地震 重复地震 尾波干涉 地壳介质变化 

分 类 号：P315.7[天文地球—地震学]