前郭M_S5.8级震群型地震前榆树地震台地电场异常分析

ABNORMAL ANALYSIS OF GEOELECTRIC FIELD AT YUSHU SEISMIC STATION BEFORE THE QIANGUO MS5.8 EARTHQUAKES SWARM OF JILIN PROVINCE

2013年10—12月,吉林前郭发生MS 5.8级震群型地震。榆树台距离震中210km,通过检查和分析该台地电场观测资料,发现此次震群型地震前记录到明显的地电场异常信号,主要表现为:地电场多测道时均值曲线出现连续同步畸变,地电场长、短极距比值出现较大幅度成丛变化,相关系数降低,差值增大;短期异常出现在震前在3个月内,最长持续时间近1个月;临震异常出现在震前1个月内,最长持续时间近半个月。本文通过总结,将为今后吉林省中强地震预测提供依据。

MS5.8 earthquakes swarm in Qianguo of Jilin Province happened in 2013 October to December. We found that there are obvious abnormal geoelectric signals before the earthquake swarm, at Yushu Seismic station 210km away from the epicenter. The main performances are：the curves of hour average of multi measuring channel at geoelectric field appear continuous synchrous distortion, larger clumps of changes for the ratio of long to short electrode spacing observation in the same measuring direction come, the correlation coefficient decrease,and zeroing differences for data from long and short polar distance observations increase. Short term anomalies appeared before the earthquakes swarm in 3 months, and the longest duration is nearly 1 months; Impending earthquake anomalies appeared before earthquakes swarm in 1 months, and the longest duration is nearly half a month. This article summarizes,it will provide reference for medium-strong earthquake prediction in Jilin Province.