In this study,we collected the geological,electrical strata,and electrical sounding data from the Linfen seismic station in the Shanxi Province,China.According to this information,the electrical structure of the medium beneath the Linfen station was simplified as a two dimensional electric section.On this basis,a three-dimensional inhomogeneous finite element model was con-structed,and the electrical structure of the strata in the study area was analyzed.The results show that the earth resistivity will increase with rainfall,which explains why the georesistivity in the Linfen station shows a high feature in the summer and a low one in the winter.In addition, the impact of rainfall on earth resistivity increases with depth,which is also concerned with media uniformity and geological factors.The rise of the water level in surrounding canals has little effect on the earth resistivity;therefore,it is believed that the gradual decrease of georesistivity since 2010 is not related to canals.The study has great significance to the interference factors of earth resistivity and possible earthquake precursors.%依据山西省临汾地震台地质资料、岩层电性资料和台站电测深曲线,将该台地下介质电性分布简化为二维电性结构,在此基础上,构建了三维非均匀层状介质有限元模型.三维有限元模型采用水平层状结构,假定浅层三层介质电阻率均匀.依据电测深曲线及水平层状模型,借助地电阻率观测资料获取测区地层电性结构.通过第一层介质电阻率变化模拟了2个测道的浅层介质电阻率变化,分别是测区NS向表层介质电阻率随季节性降雨的变化和EW向浅层介质电阻率随水渠水深的变化.计算结果表明,降雨对地电阻率会造成升高影响,解释了临汾地电年变形态"夏高冬低"的原因;此外,降雨对地电阻率的影响还随深度的增加而增大,同时还与介质均匀性、地质因素等有关.测区附近水渠内水位的加深对电阻率造成的变化很小,认为2010年以来的趋势下降异常跟水渠干扰关系很小.研究结果将会对地电阻率的干扰因素以及可能出现的前兆指示具有重要的意义.
展开▼
