2018年松原M5.7地震前地电场变化特征研究

Study on the Change Characteristics of Geoelectric Field before the Songyuan M5.7 Earthquake in 2018

运用常规波形、地电场日变幅各向异性度、差值法与渗流方位角法对不同时长四平台、长春台、榆树台、绥化台的地电场观测数据进行分析,结果显示:各台能够记录到地震异常,其中榆树台、绥化台地电场在震前6~10 d日变畸变明显。四个台地电场日变幅各向异性都存在超过2倍均方差的3~4个月的短期异常,其中长春台、榆树台、四平台相对明显。长春台NS向与榆树台EW向归零差值法分别存在2个多月、1个多月的短期异常,绥化台归零差值法的异常偏弱,四平台部分时段受到干扰,应判定无异常。对于渗流方位角方法 ,四平台、榆树台与绥化台异常特征较明显,长春台异常相对较弱。各类分析方法存在一定的差异性,异常出现的早晚也各不相同,这与各台的电性条件、发震构造与各台构造关联性存在一定关系。

The paper analyzes the geoelectric field observation data of the Siping,Changchun,Yushu and Suihua stations by using conventional waveform,daily amplitude anisotropy of geoelectric field,difference method and seepage azimuth method for different durations.The results show that all stations can record seismic anomalies,and the geoelectric field of Yushu station and Suihua station have obvious daily distortion 6-10 days before the earthquake.The daily amplitude anisotropy of the four stations has a short-term anomaly of more than 2 times the mean square error for 3-4 months,and the abnormalities of the Changchun,Yushu and Siping stations are relatively obvious.There are short-term anomalies of more than 2 months or more than 1 month in the NS direction of Changchun station and EW direction of Yushu station.The abnormality of the method of zero return difference of Suihua station is weak.The Siping station was disturbed during part time,and there should be no abnormalities.For the seepage azimuth method,the anomaly characteristics of the Siping station,the Yushu station and the Suihua station are more obvious,and that of the Changchun station is relatively weak.There are certain differences between different methods,and the abnormal time is also different,which has a certain relationship with the electrical conditions of each station,the correlation between the seismogenic structure and each station structure.