摘要
本文用粘弹性理论,探讨了老断层失稳扩展型地震的孕育过程中,断层泥的作用问题.得到了如下结果:即使区域背景场和扰动场保持不变,断层局部应力场仍会因断层泥的蠕变而变化.其中切向应力分量δ_(ηη)~0(t),在其它所有分量都缓慢衰减的同时缓慢增大.一旦这个应力分量在断层尖端附近的极大值点,积累至大于岩石的断裂强度,断层的失稳扩展便会从这点发生.与空腔断层相比,断层泥使δ_(ηη)~0(t)的突变过程变成了缓慢渐近过程,并使δ_ηη~0(t)的渐近值有所降低,因而会推迟和减少地震的发生.文中还讨论了断层失稳扩展方向等问题.
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 (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.
出处
《地震学报》
CSCD
北大核心
1990年第3期248-256,337,共9页
Acta Seismologica Sinica
