科研之友
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摘要
In this paper, we discussed the physical processes of the medium in/near the focal region in the late preparation period of strong earthquake, theoretically proved the orthogonal relation between the maximum loading direction and the direction of most prominent change in apparent resistivity, and produced the constitutive relations of anisotropic changes in true resistivity and apparent resistivity to crack ratio upsilon, crackwater resistivity rho f and framework resistivity p., and then proposed a possible reason for the anisotropic changes in apparent resistivity. We consider that in/near the focal region in the late preparation period of strong earthquake, the micro-cracks in the crust medium develop fast in number and size, which strike predominantly along the maximum compressional stress orientation of focal mechanism solution, and then the low resistance crack-water comes fast in and conductive aisles connect each other. The physical processes generate the anisotropic changes in true resistivity, in which the most prominent change is in the direction in or close to the maximum compressional stress orientation, and the true anisotropic changes cause the anisotropic changes in apparent resistivity, in which the most prominent change is in the direction perpendicular or nearly perpendicular to the orientation. The underground water with low resistance plays a very important role in the above physical processes.
- 出版日期2007-11
- 单位中国地震局兰州地震研究所; 北京市地震局; 中国地震台网中心
