2017年11月23日，重庆武隆发生MS 5.0地震，震后1个月内发生107次ML≥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MS 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 MS 5.0 earthquake occurred in Wulong, Chongqing. Within one month after the Wulong MS 5.0 earthquake, 107 earthquakes with ML ≥ 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 MS 5.0 earthquake. The variation of crustal media in the focal area after the Wulong MS 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 MS 5.0 earthquake;④The recovery process of seismic wave velocity rise to fall in the local area after the Wulong MS 5.0 earthquake is also found.
2021,42(3): 64-73 收稿日期：2021-01-26
DOI：10.3969/j.issn.1003-3246.2021.03.008
基金项目：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
作者简介：汪建(1987-),男,本科,工程师,主要从事重复地震等研究。E-mail:373271967@qq.com
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