摘要
利用全国统一目录和流动台站目录,研究了四川盆地东南部长宁地区的地震活动特征和b值的空间分布特征。研究结果显示,长宁地区的地震活动在时间上呈现明显的分段特征,地震活动在2015年后明显增强;在空间上,长宁地区的地震活动主要集中在以28.3°N为界限的南、北2个地区,对于这2个区域的b值演化,计算结果显示出不同的分段特征。此外,研究了不同震中距下,长宁地区2018年兴文5.7级、2019年珙县5.3级和2019年长宁6.0级3次主要地震事件震前与震后的b值演化,结果表明统计范围会显著影响b值的变化特征,当计算范围为20km时,3次主震震前短期内均出现了低于背景b值90%的低b值异常,这表明在地震目录相对完备的情况下,利用低b值异常分析区域地震危险性,应采用较小范围的地震数据。
In this article,we use both unified national catalog and catalog from mobile station to study the characteristics of seismicity and the evolution characteristics of b-values in the Changning area of southeastern region of Sichuan Basin.The results show that the seismicity in the Changning area has shown obvious multi-stage segmentation characteristics in time,and the seismicity increases significantly after 2015.Moreover,earthquakes are mainly concentrated in Gongxian,Xingwen,and Junlian.For the temporal evolution of b-value of the two areas,the segmentation characteristics are different.We also study the evolution of b-value before and after the major three M_(S)5 events,Xingwen M_(S)5.7,Gongxian M_(S)5.3,and Changning M_(S)6.0,in the Changning area with different epicenter distances.The results show that the epicenter distance significantly affects the evolution of b-value.When the epicenter distance is 10km,remarkble low b-value anomalies appear in short term before all M5 earthquakes,which implies that when analyzing the low b-value anomalies or the seismic hazard,earthquake catalog within a smaller range should be used.
作者
解孟雨
孟令媛
Xie Mengyu;Meng Lingyuan(China Earthquake Networks Center,Beijing 100045,China)
出处
《中国地震》
北大核心
2021年第2期494-507,共14页
Earthquake Research in China
基金
国家自然基金项目“页岩气水力压裂与地震活动性研究”(41974068)资助。
关键词
川东南地区
最大曲率法
兴文5.7级地震
珙县5.3级地震
长宁6.0级地震
Southeastern region of Sichuan Basin
Maximum curvature(MAXC)technique
Xingwen M_(S)5.7 earthquake
Gongxian M_(S)5.3 earthquake
Changning M_(S)6.0 earthquake
