2021年12月22日常州M_(L)4.6地震前地电阻率异常分析  

Analysis of ground resistivity anomaly before the Changzhou M_(L) 4.6 earthquake on December 22,2021

作　　者：张贵霞[1] 沈红会[1] 王丽 杨从杰[1] 王昕 袁慎杰 Zhang Guixia;Shen Honghui;Wang Li;Yang Congjie;Wang Xin;Yuan Shenjie(Jiangsu Earthquake Agency,Nanjing 210014,China;Nantong Seismic Monitoring Center Station,Jiangsu Province 226006,China;Jiangning District Earthquake Office,Nanjing 210014,China)

机构地区：[1]江苏省地震局,中国南京210014 [2]南通地震监测中心站,中国江苏226006 [3]南京市江宁区地震办公室,中国江苏210014

出　　处：《地震地磁观测与研究》2023年第5期95-106,共12页Seismological and Geomagnetic Observation and Research

基　　金：地震科技星火计划(项目编号:XH211003)。

摘　　要：在2021年12月22日常州M_(L)4.6地震前,江苏省南京、江宁、高邮地震台以及海安地震台的顾庄和桑周观测点NS向地电阻率傅里叶滑动去年变曲线均存在显著震前异常。为验证异常可靠性,统计江苏及周边地区地电阻率异常震例,拟合江苏地电阻率最大可探测距离Δ_(max)和震级M的经验公式:lgΔ_(max)=1.0861+0.2624M,获得可引起地电阻率异常变化的显著地震的界定公式:M>(lgΔ-1.0861)/0.2624;对5个站点周边的显著地震和常州M_(L)4.6地震前存在异常的NS向地电阻率去年变曲线变化进行相关性分析,结果表明,地电阻率异常变化和显著地震有较好的相关性:在地震活动平静期,地电阻率曲线相对稳定,而在显著地震活动前则出现相对明显的异常变化,且下降变化居多,在较强地震活动前下降异常尤为显著,如2016年10月20日射阳M_(L)4.8地震、2021年11月17日南黄海M_(L)5.5和12月22日常州M_(L)4.6地震。因此,南京、江宁、高邮地震台和顾庄、桑周观测点在常州M_(L)4.6地震前地电阻率异常变化真实可信。Nanjing Seismic Station,Jiangning Seismic Station,Gaoyou Seismic Station,Guzhuang Seismic Station,and Sangzhou Seismic Station in Jiangsu Province showed relatively consistent stress changes before the Changzhou M_(L)4.6 earthquake on December 22,2021.The sliding Fourier spectrum of the NS-direction earth resistivity at each seismic station showed significant preearthquake anomalies.In order to verify the reliability of the anomalies,the following work was carried out:firstly,the empirical formula suitable for Jiangsu Province for the maximum epicenter distanceΔ_(max)of detectable earth resistivity anomalies and earthquake intensity M is obtained by the method of collecting historical earthquake cases related to the changes of earth resistivity anomalies in Jiangsu Province and its adjacent areas:lgΔ_(max)=1.0861+0.2624 M.When the epicenter distance isΔ,the earthquake with M>(lgΔ-1.0861)/0.2624 is defined as a significant earthquake,which can cause abnormal variations in earth resistivity.Then the correlation analysis between abnormal variations of ground resistivity after eliminating the annual trend and the significant earthquakes around the seismic station is carried out.The analysis results show that there is a good correlation between the earth’s resistivity variations and significant earthquakes.It is relatively stable in quiet periods of seismic activity and fluctuates or shows declining changes greatly before significant earthquakes.The abnormal variations are more obvious before stronger seismic activities,such as the Sheyang M_(L)4.8 earthquake on October 20,2016,the South Yellow Sea M_(L)5.5 earthquake on November 17,2021,and the Changzhou M_(L)4.6 earthquake on December 22,2021.Therefore,the anomalous changes in ground resistivity before the Changzhou M_(L)4.6 earthquake at the Nanjing,Jiangning,and Gaoyou seismic stations,as well as the Guzhuang and Sangzhou seismic stations,are true and reliable.

关 键 词：常州M_(L)4.6地震 地电阻率异常 最大可探测距离 显著地震 去年变分析 

分 类 号：P315.722[天文地球—地震学]