2017年8月8日九寨沟7.0级地震前地磁垂直强度极化短期异常特征分析  

Analysis on Short-Term Characteristics of Geomagnetic Vertical Intensity Polarization Anomaly Before Jiuzhaigou 7.0 Earthquake on August 8,2017

作　　者：廖晓峰 樊文杰[2] 邱桂兰[1] 李雪浩[1] 杨鹏 LIAO Xiao-feng;FAN Wen-jie;QIU Gui-lan;LI Xue-hao;YANG Peng(Sichuan Earthquake Administration,Chengdu 610041,China;Yunnan Earthquake Administration,Kunming 650224,China)

机构地区：[1]四川省地震局,四川成都610041 [2]云南省地震局,云南昆明650224

出　　处：《地震》2021年第4期68-77,共10页Earthquake

基　　金：2020年度震情跟踪定向工作任务(2020010405);四川省科技厅项目(2018JY0428);2019年度震情跟踪定向工作任务(2019010415)。

摘　　要：对2017年8月8日九寨沟7.0级地震前后四川及其邻区地磁台站数据进行垂直强度极化方法计算,使用5~100 s周期发现震前地磁极化计算结果存在如下的显著异常特征:①2017年3月震中附近地磁台站同步存在极化超阈值异常,时间上显示为短期异常;②同步异常台站出现最大幅度的时间较一致;③九寨沟地震发生在异常阈值线附近,对该方法预测地点有一定指示意义;④对比异常时段内的Dst指数,认为此次同步超阈值异常不是空间电流体系所造成的;⑤3月18日地磁台站出现极化异常的台站数量较多,异常分布区域面积较大,异常主要集中在西北地区可能反映了该区域的应力作用。The vertical intensity polarization is calculated by using the geomagnetic data of Sichuan and its adjacent areas before and after the Jiuzhaigou M_(S)7.0 earthquake on August 8,2017.The geomagnetic polarization results at 5~100 s frequency band before the earthquake have the following obvious abnormal characteristics:①In March 2017,the geomagnetic stations near the epicenter synchronously showed polarization over threshold anomalies,which are short-term anomalies in time.②The occurrence time of the maximum amplitude was consistent for abnormal stations.③The Jiuzhaigou earthquake occurred near the anomaly threshold line,which has a certain indication significance for the prediction location of this method.④Compared the Dst index in the abnormal period,it is considered that the synchronous anomalies over threshold were not caused by the space current system.⑤On March 18,there were more stations with polarization anomalies to cover a larger area,and the anomalies mainly concentrating in Northwest China may illustrate the stress effects in this region.

关 键 词：九寨沟地震 地磁 频段 垂直强度极化方法 异常特征 

分 类 号：P315.7[天文地球—地震学]