辽宁南部地区地壳剪切波分裂特征  

Characteristics of Shear-Wave Splitting in the Crust in Southern Liaoning Region

作　　者：夏彩韵 张正帅[2] 刘庚[3] 杨士超 XIA Caiyun;ZHANG Zhengshuai;LIU Geng;YANG Shichao(Liaoning Earthquake Agency,44 North-Huanghe Street,Shenyang 110034,China;Shandong Earthquake Agency,20 East-Wenhua Road,Ji’nan 250014,China;The Second Monitoring and Application Center,CEA,316 Xiying Road,Xi’an 710054,China)

机构地区：[1]辽宁省地震局,沈阳市110034 [2]山东省地震局,济南市250014 [3]中国地震局第二监测中心,西安市710054

出　　处：《大地测量与地球动力学》2021年第2期180-185,共6页Journal of Geodesy and Geodynamics

基　　金：中国地震局地震科技星火计划(XH19008Y,XH19007Y);中国地震局青年震情跟踪课题(20200116)。

摘　　要：利用辽宁区域数字地震台网2008-01~2018-12近场小地震波形资料,采用剪切波分裂(SAM)方法计算辽宁南部地区8个台站的快剪切波偏振方向和慢剪切波时间延迟,主要分析营口(YKO)台和盖县(GAX)台的剪切波分裂参数。分析结果表明:1)8个台站的快剪切波偏振优势方向以NE-NEE和NW两个方向为主,其中5个台站的快波偏振方向为NE和NEE,与区域地质构造形态及华北北部地区的最大主应力场方向基本一致;2)对YKO台和GAX台的剪切波分裂结果进行分析,YKO台剪切波偏振优势方向自2012年起基本保持一致,表明YKO台附近构造应力场较稳定或处于应力均匀加载过程;GAX台剪切波分裂参数随时间的演化较为复杂,其快波偏振方向在2013年小震增强前后发生明显改变,慢波时间延迟较其他台站大,可能反映GAX台下方的地壳各向异性强于其他地区,从而为进一步了解区域应力场特征和构造环境提供理论依据。We use the shear-wave splitting(SAM)method to calculate the fast shear-waves polarization direction and slow shear-waves time delay of 8 stations in southern Liaoning,based on near-field small seismic waveform data of seismic network from 2008-01 to 2018-12 in Liaoning Region.We mainly analyze the shear-wave splitting parameters of Yingkou(YKO)station and Gaixian(GAX)station.The results show that:1)The dominant polarization directions of the fast shear-waves at the 8 stations are mainly NE-NEE and NW.Among them,the fast wave polarization directions of 5 stations are NE and NEE,which are basically consistent with the regional geological structure and the direction of the maximum principal stress field in northern North China.2)The detailed analysis of the shear-wave splitting results of YKO and GAX stations show that the dominant polarization directions of the shear-waves of YKO station have basically been consistent since 2012,indicating that the tectonic stress field near YKO station is relatively stable or in the process of uniform stress loading;the evolution of shear-wave splitting parameters of GAX station over time is more complicated,and its fast-wave polarization direction has changed significantly before and after the small earthquake intensification in 2013.The time delay is larger than other stations,which may reflect that the crustal anisotropy below GAX station is stronger than other regions.That can provide a theoretical basis for further understanding of regional stress field characteristics and tectonic environment.

关 键 词：辽宁地区 地壳各向异性 剪切波分裂 主压应力 

分 类 号：P315[天文地球—地震学]