唐山老震区M≥4.0地震前b值变化异常特征研究  

Anormalies of b-value Changes before M≥4.0 Earthquake in Tangshan Old Seismic Region

作　　者：岳晓媛[1] 李艳娥[2] 钟世军[1] 王薇 王燕 马梁 YUE Xiao-yuan;LI Yan-e;ZHONG Shi-jun;WANG Wei;WANG Yan;MA Liang(Beijing Earthquake Agency,Beijing 100080,China;Institute of Geophysics,China Earthquake Administration,Beijing 100081,China)

机构地区：[1]北京市地震局,北京100080 [2]中国地震局地球物理研究所,北京100081

出　　处：《地震》2024年第1期94-108,共15页Earthquake

基　　金：北京市地震局科技项目(BJWC-2023013)。

摘　　要：选取2009年1月至2022年12月唐山老震区的地震目录资料计算b值,利用格点搜索法确定b值下降幅度较大(≥20%)的区域作为异常区,分析该区域b值的时间变化特征,结合b值的时空变化研究该区域发生M4.0以上地震的危险性。研究发现,唐山老震区7次(组)M4.0以上地震均发生在b值下降幅度较大的区域边缘或附近,表明应力较高的区域是地震危险区。异常区域内b值的时间变化显示,7次(组)M4.0以上地震多在震前半年至一年出现b值下降的变化过程,也反映了异常区域应力逐渐积累的过程。总体来说,b值的时空下降变化对唐山老震区M4.0以上地震的研判具有指示意义。We select the data of earthquake catalogue from January 2009 to December 2022 in Tangshan old seismic region to calculate the b-value.The lattice searching method is used to determine the abnormal area with a significantly decrease in b-value(≥20%),the time variation characteristics of the b-value in this area are analyzed,the risk of M≥4.0 earthquakes in the area is studied based on the b-value spatiotemporal variation characteris-tics.The research has found that 7 M≥4.O earthquakes occurred at or near the edges of areas with significantly decrease in b-values in the Tangshan old earthquake area,which indicates that areas with high regional stress are high-risk areas for earthquake occurrence.According to the time changes of b-values in the abnormal area,most of the 7 M≥4.O earthquakes(groups)experienced a decrease in b-values from half a year to one year before the earthquake,which also reflects the gradual accumulation of stress in the abnormal area.The b-value decrease in time and space has indicative significance for the study and judgment of M≥4.O earthquakes in the Tangshan old seismic region.

关 键 词：唐山老震区 异常特征 B值 格点搜索 

分 类 号：P315.7[天文地球—地震学]