新沂地震台地电阻率反向年变分析

结合新沂地震台电测深曲线、 测区地质剖面资料, 建立了三维非均匀层状介质有限元模型. 以第一层介质电阻率变化模拟表层介质电阻率随季节性降雨的变化， 在模型中计算了3个测道的地电阻率年变化形态. 计算结果表明， EW和N45°E测道地电阻率随表层介质电阻率的增减同向增减， 而NS测道地电阻率则与表层介质电阻率变化相反. 该结果符合新沂台3个测道实际观测的年变形态． 

Reverse annual variation of georesistivity at Xinyi seismic station,Jiangsu Province

Combined with geologic section and electric sounding data, a three-dimensional inhomogeneous finite element model was constructed to analyze annual variation of georesistivity at Xinyi seismic station. Resistivity variation of shallow layer, which was caused by seasonal rainfalls, was substituted with resistivity changes of the first layer in the finite element model. Annual variation of georesistivity in NS, EW and N45°E channels are calculated based on the model. Analyzed results of the model suggest that georesistivity in EW and N45°E direction increases/decreases with resistivity of the first layer increasing/decreasing, while georesistivity in NS direction varies in an reverse way. The model results accord with observations in the three monitoring directions at the Xinyi station.