2019年长宁MS6.0地震邻区分钟采样地电场分析

Analysis of Anomalies in Geoelectric Field Around 2019 Changning MS6.0 Earthquake

2019年6月17日四川宜宾市长宁县发生M_S6.0地震,分析震中周边600 km内7个地电场台站观测分钟值数据,获知震前2个月左右红格等6个台站地电场均存在不同方位之间、同方位长短极距之间的相关系数持续降低,6月17日这些相关系数基本降至最低,反映出这6个场地的地电场在此次地震前后发生了非均匀变化;同时,这6个台站的地电场优势方位角出现了约45°或90°跃变,并伴有显著发散或收窄现象。分析表明长宁M_S6.0地震前后,这6个场地的多种地电场异常现象具有局部场地效应、时间准同步性。

On June 17,2019,there occurred a M_S6.0 earthquake in Changning County,Yibin City,Sichuan Province.The minute values of seven geoelectrical stations within 600 km of the epicenter was analyzed.The geoelectric field correlation coefficients between different directions and between the long and short pole distance continuously reduced at six stations about two months before the earthquake,and these correlation coefficients declined to a minimum on June 17,reflecting the non-uniform variation in the geoelectric field at these six sites before or after the earthquake.Simultaneously,the dominant azimuth angle of the geoelectric field jumped approximately 45°or 90°at these six stations,and also significantly diverged or shrunk.The analysis shows that around the Changning M_S6.0 earthquake,the anomalies at these six geoelectric field stations exhibited local effects and quasi-synchronous characteristics.