九寨沟7.0级地震前四川地区地磁异常分析

Analysis of Geomagnetic Anomalies of Sichuan Associated with the Jiuzhaigou M7.0 earthquake

利用地磁垂直分量日变幅逐日比方法分析了2017年8月8日九寨沟7.0级地震前的地磁异常时空变化特征,结果表明:震前6个月成都、松潘、江油和崇州4个台站出现了同步的逐日比超阈值异常,异常台站集中于四川北部地区,震中位于异常阈值线上。外空场活动调查排除了空间环境对计算结果的影响,显示此次多台同步逐日比异常很可能是浅层地下介质电性结构改变的一种表现。

Using the diurnal variation of the geomagnetic vertical component to analysis on the varying space-time characteristics of geomagnetic anomalies .The results show that Chengdu, Songpan, Jiangyou and Chongzhou seismological station all showed supra-threshold abnormal in daily ration at the same time before Jiuzhaigou M 7.0 earthquake, which located on the threshold line. The investigation of outer space field activation exclude from space environment interference to calculation result, which means that the geomagnetic anomalies might be caused by the change of shallow ground media electrical structure.