强震前视电阻率月速率变化特征分析

Research on Normalized Variation Characteristics of Apparent Resistivity Before Strong Earthquakes

用归一化月速率方法处理了2次强震前周边7个地电阻率台的观测数据,并结合震源机制解计算结果,研究了强震前后视电阻率各项异性变化及映震特征。研究结果表明,与震源机制解最大主压应力方位正交(或近于正交)测道的视电阻率,在地震前1年内,大部分台站视电阻率月速率值出现下降和短临阶段上升变化,而与主压应力方位一致(或近于该方位)的测道变化则相反。基于这一物理现象,若能加大观测台网密度、合理布设电极方位,就有可能推断出地震震中的大致位置。

Using Normalized variation rate method, we study the resistivity data of 7 stations in the epicenter areas of 2 strong earthquakes before the events. The relationship between variation of anisotropic apparent resistivity and the focal mechanism solution of earthquake is analyzed. The result shows that significant apparent resistivity variation occurs in the direction that is perpendicular to the azimuth of the maximum principal stress while only small fluctuation are recorded in the direction of the maximum principal stress. Most of the anisotropic resistivity variation occurs in the late stage of the development of a strong earthquake, which can be observed in the epicenter area. If the density of the observation stations can be increased and the direction of the observed resistivity can be appropriately set, the epicenter of an earthquake may be estimated by the observed resistivity anomaly.