低频电阻率法在地震预报中的应用

短周期地震预报现在仍是一个难题,但它非常重要。低频电阻率法是一种可用的方法。岩石形变导致岩石电阻率变化,变化的幅度不但决定于形变的大小,而且决定于地压的方向。无论何种类型的地震由于地压效应,岩石均会发生形变,虽然地震看起来是一个突发事件,但其形成和发展是一个过程。在能量积聚期间,地压逐渐增加,相应地岩石发生形变。然而,形变随时间变化的梯度是很小的。因此形变电阻率也很小,在这种情况下,岩石的形变大多数是弹性形变。在能量释放阶段,在能量积聚最集中的部位,将超过弹性限度,以致产生永久形变,因此在会发生地震的某些范围内,形变电阻率将可以观测到。

APPLICATI0N OF LOW FREQUENCY RESISTIVITY METHOD TO PREDICTION OF EARTHQUAKES

At present, the short-duration prediction of an earthquake is still a difficult problem, but it isparticularly important. Low frefuency resistivity method is an applicable route. Deformation of rocks will result in the variation of its resistivity, and the variation amplitudedepends on the magnitude of the deformation as well as the direction of geostress. Regardless ofthe type of earthquake, all rock happens to deform due to the effect of geostress. Although anearthquake seems like a sudden event its formation and development is a process. During the energy accumulation, geostress increases gradually, and correspondingly rock happensto deform. However, the variation gradient of deformation with respect to time is small, so thedeformation resistivity is also small. In this case, deformation of rocks is in the majority of fle-xible deformation. At the stage of releasing energy, the region where energy accumulates most intensively willexceed the flexible limit so as to set up the permanent deformation. For this reason, within thecertain scope of the subsequent epicentral area, deformation resistivity will be able to be observed.