四川威远地区近震剪切波分裂特征  

Shear wave splitting of local earthquakes in Weiyuan area,Sichuan

作　　者：高瑜[1] 刘莎[1] 郑钰[1] Gao Yu;Liu Sha;Zheng Yu(Institute of Geophysics,China Earthquake Administration,Beijing 100081,China)

机构地区：[1]中国地震局地球物理研究所,中国北京100081

出　　处：《地震学报》2023年第4期645-657,共13页Acta Seismologica Sinica

基　　金：国家自然科学基金项目(41904057);国家重点研发计划(2018YFC1503402);中国地震局地球物理研究所基本科研业务费重大研究计划(DQJB19A0115)共同资助.

摘　　要：基于布设在四川威远地区的流动地震台站2019年11月至2020年5月记录的近震波形数据,利用剪切波分裂分析方法获得了研究区内23个地震台站的剪切波分裂参数。结果显示:威远地区地震台站快波偏振方向多数为北西向,与区域主压应力方向一致;有个别台站可能由于受到局部构造环境的影响,快波偏振方向为北东向。而在地壳速度变化明显的威远背斜附近,有6个台站结果显示为两个快波偏振优势方向,表明该地区快波偏振方向是区域应力场和局部构造环境共同作用的结果,威远地区慢波延迟时间均值为4.43 ms/km,威远背斜南侧区域的慢波延迟时间值普遍大于其北部区域,表明在威远地区南部区域的各向异性强度强于北部区域。In this paper,the shear wave splitting parameters of 23 seismic stations in Weiyuan area,Sichuan are obtained using the shear wave splitting analysis method,base on the local earthquake waveform data recorded by the temporary seismic stations from November 2019 to May 2020 in the study area.The results show that the polarization directions of fast shear wave at most stations in Weiyuan area are northwest,which is consistent with the direction of regional principal compressive stress.And the polarization directions of a few stations are northeast,which may be affected by the local tectonic environment.Near Weiyuan anticline with obvious differences in crustal velocity,there are six stations with two dominant polarization directions of fast wave,indicating that the polarization direction of fast wave in this area is influenced by the combined effects of regional stress field and local tectonic environment.The average delay time of slow wave in Weiyuan area is 4.43 ms/km.And the delay time of slow wave in the south of Weiyuan anticline is generally greater than that in the north,suggesting that the aniso-tropy intensity in the south of Weiyuan area is stronger than that in the north.

关 键 词：剪切波分裂 快波偏振方向 慢波延迟时间 区域主压应力 

分 类 号：P315.3[天文地球—地震学]