2014年大同地电阻率NW测向异常分析

Anomaly analysis of earth resistivity in NW direction at Datong in 2014

2014年大同地震台地电阻率NW测向出现年变畸变现象,经现场调查,发现观测环境、观测系统正常;利用褶积滤波法去除降雨量和地下水位影响,发现年变幅减小变化依旧存在;应用小波变换方法进行处理,发现小波能谱可较好反映地电阻率变化,且2014年NW向地电阻率数据的小波能谱及其相对变化显著增大,而在张北及大同成组地震前,曾出现类似变化,而且小波能谱值越大,对应发生的地震震级越大。

The annual aberration of resistivity of NW component at Datong station has been detected since 2014. After investigation,we found that the observation system is working properly, surrounding environment changes and geo-electric resistivity are not synchronized in time. The anomaly still exists after removing the effects of rainfall by convolution filtering method. After Wavelet transform technique be applied to the analysis of geo-resistivity data, the wavelet power spectrum can well respond to the geo-resistivity variation. The wavelet power spectrum and its relative variation increased greatly in NW direction in 2014, similar to the increment before Datong and Zhangbei earthquake group. And the wavelet power spectrum value is greater with corresponding to the greater earthquake magnitude.