利用双差地震成像方法反演辽南地区地壳速度结构  

CRUSTAL VELOCITY STRUCTURE BENEATH THE SOUTHERN LIAONING PROVINCE DERIVED FROM DOUBLE DIFFERENCE TOMOGRAPHY

作　　者：王亮[1] 焦明若[1] 钱蕊[1] 张博[1] 杨士超 邵媛媛[1] WANG Liang;JIAO Ming-ruo;QIAN Rui;ZHANG Bo;YANG Shi-chao;SHAO Yuan-yuan(Liaoning Earthquake Agency,Shenyang 110034,China)

机构地区：[1]辽宁省地震局,沈阳110043

出　　处：《地震地质》2022年第2期378-394,共17页Seismology and Geology

基　　金：中国地震局地震预测研究所基本科研业务专项(2018IEF010201);辽宁省科学技术计划社发攻关及产业化项目(2017231013)共同资助。

摘　　要：文中利用辽宁地区“十五”改造前后共67个区域地震台记录的1975年8月—2017年12月期间的地震震相观测报告,通过双差地震成像的方法,采用tomoDD软件对辽南地区进行了地震重新定位及速度结构反演。通过计算得到了辽南地区记录大部分地震的重新定位结果和4km、13km、24km、33km几个深度上较好的P波速度结果。重新定位结果显示,海城余震区和盖州震群活动区域作为辽南地区主要的地震活动区域,其地震活动具有明显的NW向展布特征。P波层析成像结果则反映了辽南地区浅部速度结构与地质构造较为一致的特点。海城余震区所处的海城河断裂在浅层存在高速体,在4~12km深度存在低速体,且低速体向E不断加深侵入。金州断裂不同分段的端部存在高速体,其断裂端部的盖州震群发生在高速体区域,推测盖州震群的活动可能是在应力积累的条件下受到液体侵入而使岩石的含水饱和率上升所致。In recent years,the southern Liaoning Province is the main area of seismic activity in Liaoning Province,and the main geological structure units in this area include the Liaohe rift and Liaodong uplift in the east.As an important manifestation of modern tectonic activity,earthquakes are less distributed in Liaohe rift.Most of the seismic activities are concentrated in eastern Liaoning uplift area on the east side of Liaohe rift.The structure in this area is relatively complex.The revival of old faults during Quaternary is obvious,and there are more than 10 Quaternary faults.Among them,Haichenghe Fault and Jinzhou Fault are the faults with most earthquakes.The 1975 Haicheng M_(S)7.3 earthquake occurred in the Haichenghe Fault and the 1999 Xiuyan M_(S)5.4 earthquake occurred in the east of the fault.In this paper,the seismic phase bulletins are used for earthquakes from August 1975 to December 2017 recorded by 67 regional seismic stations of Liaoning Province.These stations were transformed during the Tenth Five-year Plan period.Using the double-difference tomography and tomoDD program,we relocated the earthquakes and inversed the velocity structures of the southern Liaoning area.In the study,grid method is used for model parameterization of seismic tomography,ART-PB is used for forward calculation,damped least square method is used in inversion,and checkerboard test is used for the solution evaluation.The theoretical travel time is forward calculated by taking the checkerboard velocity model of imaging meshing and plus or minus 5%of anomaly as the theoretical model.The checkerboard test results show that the checkerboard P-wave velocity model at the depths of 4 km,13 km,24 km and 35 km in the study area can be restored completely,and most areas at the depth of 33 km can also be restored completely.We calculated and got the relocations of almost all of the earthquakes in southern Liaoning area and obtained a better distribution of P wave velocities at the depth of 4 km,13 km,24 km and 33 km.The results show that ea

关 键 词：双差地震成像 重新定位 速度结构 海城余震区 盖州震群 

分 类 号：P315.2[天文地球—地震学]