2013年岷县—漳县6.6级地震前地磁日变化异常及机理分析  

Characteristics and Mechanism of Geomagnetic Diurnal Variation before the 2013 Minxian-Zhangxian MS6.6 Earthquake

作　　者：李军辉[1,2] 姜楚峰 冯志生 何康[1] 郑海刚[1] LI Junhui;JIANG Chufeng;FENG Zhisheng;HE Kang;ZHENG Haigang(Anhui Earthquake Agency, Hefei 230031, Anhui, China;Mengcheng National Geophysical Observatory, Hefei 230031, Anhui, China;Hubei Earthquake Agency, Wuhan 430071, Hubei, China;Jiangsu Earthquake Agency, Nanjing 210014, Jiangsu, China)

机构地区：[1]安徽省地震局,安徽合肥230031 [2]蒙城地球物理国家野外科学观测研究站,安徽合肥230031 [3]湖北省地震局,湖北武汉430071 [4]江苏省地震局,江苏南京210014

出　　处：《地震工程学报》2021年第3期551-558,共8页China Earthquake Engineering Journal

基　　金：中国地震局地震科技星火计划项目(XH200501);中国地震局地震预测研究所基本科研业务费专项(2020IEF0503)。

摘　　要：利用空间相关法对2013年岷县—漳县6.6级地震前后151个台站地磁垂直分量日变化进行分析,结果显示:(1)2013年7月3日、4日在震中附近分别出现16和17个台站的地磁Z分量日变化明显反相位异常,具有明显的分界线。(2)利用S变换方法对分界线两侧的天水和兰州台的Z分量日变化进行分频率相关系数计算,发现7月3日、4日的地磁Z分量的日变化均在6 h左右的周期出现负相关变化。其他时段未出现类似变化,认为岷县—漳县6.6级地震前地磁Z分量日变化异常产生的反相位异常主要在6 h左右。此外,还对异常产生的机理进行了解释。In this paper,the spatial correlation method was used to analyze the diurnal variation anomalies of geomagnetic vertical components obtained from 151 stations before and after the Minxian-Zhangxian MS6.6 earthquake in Gansu Province.The results showed that:(1)On July 3 and July 4,2013,the diurnal variation of geomagnetic Z components of 16 and 17 stations near the epicenter appeared obvious anti-phase anomalies,respectively,and there was a clear boundary between the two anomalies;(2)The S-transform method was used to calculate the correlation coefficient of the daily variation of Z component at Tianshui and Lanzhou stations on both sides of the boundary,and it is found that the daily variation of geomagnetic Z component on July 3 and July 4 both had a negative correlation at about 6 h.Therefore,it is considered that the anti-phase anomaly caused by daily variation anomaly of geomagnetic Z component before the Minxian-Zhangxian MS6.6 earthquake is mainly at about 6 h.In addition,the mechanism of the anomaly was explained.

关 键 词：地磁Z分量日变化 反相位 S变换 机理 

分 类 号：P315.73[天文地球—地震学] P318[天文地球—固体地球物理学]