基于气枪震源信号的云南漾濞M_(S)6.4地震前后波速变化  

Co-seismic velocity changes with Yunnan Yangbi M_(S)6.4 Earthquake measured by airgun source

作　　者：苏金波 杨微[1] 李孝宾 王伟涛[1] 杨军 陈颙 SU JinBo;YANG Wei;LI XiaoBin;WANG WeiTao;YANG Jun;CHEN Yong(Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Urumqi Institute of Central Asian Seismology,China Earthquake Administration,Urumqi 830011,China;Dali Center,China Seismic Experimental Site,Yunnan Dali 671000,China;School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China)

机构地区：[1]中国地震局地球物理研究所,北京100081 [2]中国地震局乌鲁木齐中亚地震研究所,乌鲁木齐830011 [3]中国地震科学实验场大理中心,云南大理671000 [4]南京大学地球科学与工程学院,南京210023

出　　处：《地球物理学报》2022年第2期649-662,共14页Chinese Journal of Geophysics

基　　金：国家重点研发项目(2018YFC1503200);中国地震局地球物理研究所基本科研业务费专项(DQJB19B32);国家自然科学基金项目(41974069,41790463);地震科技星火计划项目(XH21041Y)联合资助。

摘　　要：本文基于宾川气枪地震信号发射台激发的地震波信号,利用线性叠加和时频域相位加权叠加方法提高信噪比,通过反褶积、插值拟合和波形互相关等方法,获得2021年漾濞M;6.4地震前后气枪震源初至波信号走时变化特征.结果表明两种叠加方法得到的走时变化趋势基本一致,在沿发震断裂带附近的3个台站观测到的初至波走时延迟为7.3~14.4 ms,在射线路径上平均波速降低了0.08%~0.12%,距离震中位置较远的台站走时延迟为2~6 ms.分析认为,观测到的走时变化主要是漾濞M;6.4地震引起强地面运动造成浅层介质疏松、同震破裂导致震源区地下介质裂隙增加和地下流体侵入等共同作用造成,相关研究成果有助于加深和促进对此次地震震源物理过程的认识和了解.Based on the seismic wave signal excited by Binchuan Airgun Transmitting Seismic Station,we obtained the travel-time change with the first arrival signal of airgun source before and after Yunnan Yangbi M;6.4 earthquake in 2021,through stacked with linear and phase weighting in time-frequency domain for improved the signal-to-noise ratio(SNR),deconvolution,interpolation fitting and waveform cross-correlation.The results show that the travel-time variation trends measured by two stacking methods are basically the same.The travel-time delay of the first arrival observed at three stations near the seismogenic fault is 7.3~14.4 ms,suggesting that the average wave velocity on the ray path is reduced by about 0.08%~0.12%,and the travel-time delay of stations far from the epicenter is 2~6 ms.We found that the shallow medium loosening caused by strong ground motion,the increase of underground medium cracks in the focal area caused by co-seismic rupture,and underground fluid intrusion may generate the observed travel-time variation.Our study is helpful to deepen and promote the understanding of earthquake source process.

关 键 词：大容量气枪震源 漾濞6.4级地震 同震效应 互相关 走时变化 

分 类 号：P315[天文地球—地震学]