新疆伽师MS6.4地震前地磁日变化异常分析

ANALYSIS ON GEOMAGNETIC DIURNAL VARIATION ANOMALIES BEFORE JIASHI M S6.4 EARTHQUAKE IN XINJIANG

以新疆伽师M S6.4地震为案例,利用地磁日变化异常分析方法,对中国地磁台网所记录的地磁观测资料进行分析,结果显示:1、离震中最近的喀什台震前59 d和39 d出现一组逐日比高值异常,排除干扰,且地磁日变形态也出现明显的畸变,异常集中于震中附近台站,震中位于异常阈值线附近;2、震前,新疆及周边地区出现地磁垂直分量日变化幅度的极小值时间在空间上出现地磁低点位移现象,低点时间分界线横穿南天山西段,呈现近EW走向分布,分界线两侧低点时间相差超过2 h,发震日期为异常发生后的38(41±4)d,震中位于低点位移分界线附近;3、地磁逐日比和低点位移异常的发生时间和空间分布可能与伽师M S6.4地震的孕育和发生有非常高的关联性。该研究进一步推广和检验了地磁日变化异常分析方法在地震预报方面的应用。

Taking Jiashi M S6.4 earthquake as an example,the geomagnetic observation data recorded by Chin a’s geomagnetic network are analyzed by using the analysis method of geomagnetic daily variation anomalies.The results show that.1、A group of daily ratio high value anomalies appeared 59 days and 39 days before the Kashi station which is closest to the epicenter of the earthquake,excluding the interference,and the geomagnetic daily variation also appeared obvious distortion.The anomalies were concentrated in the stations near the epicenter,and the epicenter was near the abnormal threshold line.2、Before the earthquake,the minimum value of daily variation amplitude of geomagnetic vertical component appeared in Xinjiang and its surrounding areas,and the geomagnetic low point displacement phenomenon occurred in space,and the low point time boundary crossed the west of South Tianshan,showing near EW trend distribution,the time difference between the low points on both sides of the boundary is more than 2 h,the date of earthquake occurrence is 38(41±4)d after the occurrence of the anomaly,and the epicenter is near the low point displacement boundary.3、Temporal and spatial distribution of the geomagnetic day by day ratio and the low point displacement anomaly may have a very high correlation with the preparation and occurrence of Jiashi M S6.4 earthquake.This study further extends and tests the application of the geomagnetic daily variation anomaly analysis method in earthquake prediction.