唐山及邻区双差层析成像研究

Research on Velocity Structure of Tangshan and Adjacent Areas by Double-difference Tomography

收集唐山及邻区2010—2018年76个固定地震台站的震相数据,采用双差层析成像的方法,联合反演了唐山及其邻区中上地壳的震源位置和P波三维速度结构。结果表明:在浅层研究区P波速度的变化特征与地表地质构造和活动断裂的展布具有较好的一致性。唐山断裂两侧速度差异明显,其附近P波速度结构横向不均性显著;中地壳存在明显的低速异常,推测可能与幔源物质侵入有关。重新定位后震中位置更加集中,M_(L)3.0以上地震主要位于P波高、低速变化较强烈的区域。

In this paper,we first collected the seismic data of 76 fixed seismic stations in Tangshan and its neighboring areas from 2010 to 2018,then we inverted the source position and three-dimensional velocity structure of P-wave in the middle and upper crust of Tangshan and its adjacent areas by applying the method of double-difference tomography.The results showed that the change of P-wave velocity in shallow area is consistent with the distribution of surface geological structure and active faults.In the upper crust,the variation of P-wave velocity between the two sides of Tangshan fault is obvious,and the velocity structure of P-wave has significant lateral heterogeneity.There is a distinct low-velocity anomaly in the middle crust,which may be related to the intrusion of mantle source materials.After earthquake relocation,the distribution of epicenter position is more concentrated,and M_(L)>3.0 earthquakes are mainly located in the high and low speed transition zone of P-wave.