地震深部电性变化前兆特征及其机理的初步探讨

PRELIMINARY DISCUSSION ON THE PRECURSORY CHARACTERS AND MECHANISM OF THE SEISMIC DEEP ELECTRICAL CHANGE

摘要:

本文着重讨论了地壳内埋深约10-25km的高阻层原地条件下的导电机理,指出该层岩体导电性主要取决于其裂隙及孔隙情况和孔隙水在其中的分布。根据对部分熔体导电性的研究,对实际岩体电导率进行数字模拟发现,连接权因子增加可导致该层原地体积电阻率极大的减少。本文还分析了孔隙水参与下震源及其外围区的应力应变特征,阐明了可能出现的深部电性变化前兆的分区性及其区域的体积电阻率、电性各向异性变化特征,初步探讨了这些变化的物理机理,粗略地估计了可能的变化量值。

Abstract:

In this paper, the conductive mechanism in situ of the high-resistive layer which is 10-25 km in the crust is discussed. It is indicated that the conductivity of the rock block in the layer mainly depends On the crack-porosity behaviour and distribution of porous water in it. Using the theory and numerical modeling of conductivity of partial melt, we can see that when the connection weight factor increases, the volume conductivity in situ of the layer sharply decreases. Analysing the characters of the strain with porous water in and around the focal region, we illustrate the precursory regionalization of the deep electrical change which probably appears during earthquake readiness, explain the characters of the regional volume resistivity and conductivity anistropy change, preliminarily diccuss the physical mechanism of the electrical change, and roughly estimate the possible values.