吉林前郭5.8级震区上地壳速度结构  

Upper Crustal Velocity Structure in Qianguo M5.8 Earthquake Region

作　　者：卢燕红[1] 吴兆营[1] 丁广[1] 付琦[1] 张帆[1] Lu Yanhong;Wu Zhaoying;Ding Guang;Fu Qi;Zhang Fan(Earthquake Administration of Jilin Province, Changchun 130117, China)

机构地区：[1]吉林省地震局,长春130117

出　　处：《吉林大学学报（地球科学版）》2017年第6期1894-1903,共10页Journal of Jilin University：Earth Science Edition

基　　金：吉林省科技发展计划项目(20150204002SF;20130204052SF)~~

摘　　要：为了更好地研究吉林前郭地区的地震活动性,本文利用2013年10月至2015年2月吉林前郭5.8级震群周围17个地震台站记录到的405个地震事件资料,共获得2 218条P波走时数据和2 166条S波走时数据,采用地震双差层析成像技术,获取吉林前郭震区上地壳三维P波、S波速度精细结构。结果显示,震区上地壳速度分层明显,P波速度变化范围为5.8~7.2km/s,S波速度变化范围为3.4~4.0km/s,波速比(vP/vS)变化较小。震区有低速带穿过,低速带走向为北东向,倾角较大(近直立),纵向延伸至15km深度;震群主要位于低P波和S波速度区,对应较低的波速比。吉林前郭震区构造强度较低,受西太平洋板块俯冲产生应力场的影响,易于发生地震。For further studying seismic activity of Qianguo in Jilin Province,we collected405seismic events recorded by17permanent and temporary stations from October2013to February2015,and total2218highquality P wave arrival times and2166highquality S wave arrival times.We used doubledifference tomography method to invert the upper crust P and S wave velocity structure in Qianguo region(in the region of epicentral distance range of0-200km).The tomography results show that the velocity structure beneath thestudy area exhibits an obvious feature of stratification,the P wave velocity varies from5.8km/s to7.2km/s,and the S wave velocity is from3.4km/s to4.0km/s,with a small change on the vP/vS ratio.A low velocity zone beneath thestudy area is found with a trend of NE direction and a nearly vertical steep dip angle,and it extends as deep as15km.The earthquake cluster is located in the low P wave and low S wave velocity region corresponding to a low vP/vS ratio;so we suggest that the tectonic intensity of this region is weak,and prone toearthquake under the influence of the stress field derived from the subduction of Western Pacific slab.

关 键 词：前郭震区 双差层析成像 速度结构 上地壳 

分 类 号：P631.4[天文地球—地质矿产勘探]