巧家M_(s)5.0地震的地磁异常过程分析

The process analysis on geomagnetic anomalies of Qiaojia M_(s)5.0 earthquake

通过2020年5月18日巧家M_(s)5.0级地震的震中周边200 km范围内的地磁总强度和地磁矢量监测区域震前至震后几期的测量数据对比,分析了巧家地震的地磁异常特征.结果表明,巧家地震的地磁异常在震前14个月开始出现,震中在磁偏角、磁倾角的零变线上,且在水平分量弱变区域中—而不是在地磁要素变化大的区域.距震中越远,这些地磁要素的变化有增大的趋势.

The abnormal characteristics of magnetic field of Qiaojia M_(s)5.0 earthquake are analyzed by comparing the data of geomagnetic total intensity and magnetic field vector measured several times before and after Qiaojia M_(s)5.0 earthquake that happened on May 18,2020 in the monitoring region within 200 kilometers around the epicenter.The results show that the abnormal geomagnetic field had begun to arise 14 months before the earthquake happened;The epicenter was on the zero-variant-line of magnetic declination and magnetic incidence,and it was in the weakly variable region of horizontal magnetic field vector but not in the region where geomagnetic elements varied greatly.And the further from the epicenter,the greater will the variation of these geomagnetic elements tend to increase.