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.