摘要
Based on the heterogeneity of fault plane strength,the macro rupture process of a fault plane can be treated as the rupture accumulation process of local micro-elements in the fault surface.Assuming that the strength of the local micro-elements follows the Weibull probability distribution,the macro-fault constitutive relationship of the complete load-deformation process is derived from a statistical mechanics viewpoint.Applying a one-dimensional earthquake mechanics model and using far-field displacement a as the control variable,the problem of earthquake instability is investigated by employing the stability theory.The results show that the system stiffness ratio(stiffness ratio of fault to surroun-ding rock) β is the important parameter that affects the occurrence of earthquakes.Earthquake instability occurs only when β < 1,and the sudden stress jump appears at the displacement turning point of the equilibrium path curve.The expression of three important parameters for earthquakes(fault half-dislocation distance after earthquake,earthquake stress drop and elastic energy release) is also given.When β≥1,the earthquake does not occur and the fault only slips slowly without an earthquake.
Based on the heterogeneity of fault plane strength, the macro rupture process of a fault plane can be treated as the rupture accumulation process of local micro-elements in the fault surface. Assuming that the strength of the local micro-elements follows the Weibull probability distribution, the macro-fault constitutive relationship of the complete load-deformation process is derived from a statistical mechanics viewpoint. Applying a one-dimensional earthquake mechanics model and using far-field displacement a as the control variable, the problem of earthquake instability is investigated by employing the stability theory. The results show that the system stiffness ratio (stiffness ratio of fault to surroun-ding rock) β is the important parameter that affects the occurrence of earthquakes. Earthquake instability occurs only when β 〈 1, and the sudden stress jump appears at the displacement turning point of the equilibrium path curve. The expression of three important parameters for earthquakes (fault half-dislocation distance after earthquake, earthquake stress drop and elastic energy release) is also given. When β≥ 1, the earthquake does not occur and the fault only slips slowly without an earthquake.
基金
supported by the Central Public-interest Scientific Institution Basal Research Fund of Institute of Geophysics,China Earthquake Administration(DQJB08B21)
关键词
地震后
不稳定
简单模型
地震应力降
平面非均质性
稳定性理论
断层面
元素积累
Earthquake instability
Fault rupture
Weibuil probability distribution
Fault constitutive relation
Equilibrium path curve
Stress sudden jump