临夏台地电阻率变化与震兆现象分析

Analysis on the variation of the earth resistivity and seismic precursory phenomena at Linxia seismic station, Gansu

摘要:

以甘肃省临夏台1981年以来的地电阻率资料为基础,利用数理统计和相关分析方法,分析该台地电阻率的变化特征,探讨EW和NS两测向之间数据的相关性,以及与大夏河流量变化的对应关系,认为该台两测向数据间具有很高的相关性,可能与区域地下介质具有较均匀的电性结构有关;分析了该区降水和地下静水位对地电阻率的影响,认为地下静水位的影响更显著。此外,探讨了临夏台地电阻率资料作为地震前兆的意义,认为该台资料对甘东南及甘青交界地区的中强地震反应敏感,以下降型破年变异常为主,呈现出震级越大,异常持续时间越长的特点。该台资料同时对甘青地区成组中强地震有所反应,显示出异常持续时间长、幅度大和恢复慢的特点。

Abstract:

The paper studies the observational data of earth resistivity in Linxia seismic station, Gansu, since 1981. To discuss the corresponding relation between the two direction findings, EW and NS, and the flow rate change of Daxia River, the variation characteristics of earth resistivity were analyzed by using mathematical statistics and correlation analysis methods. It can be concluded that there was a high correlation at the two direction findings, which was probably related to the electricity structure of underground media. In addition, analyzing the impact of precipitation and the static water level, we found that the influence of static level is remarkable. Besides, the data of earth resistivity is sensitive to the moderately strong earthquakes which occurred in the southwest of Gansu and the junction of Gansu and Qinghai. The abnormal annual descend is the main precursory anomaly information, which showed that there is a greater magnitude with a longer duration of abnormality. The anomalous change of the earth resistivity is remarkable in the moderately strong earthquake group of Gansu and Qinghai regions, indicating that the duration of abnormal was long, the amplitude of variation was large and the recovering time was slow.