THE ROLE OF FAULT GOUGE IN THE DEISMOGENIC PROCESS

In terms of visco-elasticity theory,the problem of what role the fault gouge plays in the seismogenic process is investigated in this paper. The results are as follows; Even though the background tectonic stress and the disturbing stress fields keep constant,the local stress field around the fault plane varies with fault creep due to the rheologic property of the fault gouge. While all other stress components are decreasing,the shear stress σ⁰_ηη(t) on the fault plane increases gradually. When the shear stress surpasses the rock strength at the point of maximum stress near the tip of the fault,fault fracture will occur here instantaneously. Comparing a fictitious fault having no gouge between the walls with a natural one,the fault gouge will delay the occurrence and reduce the number of earthquakes. Some problems,such as the orientation of fracture etc.,are also discussed.