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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. Whilst β ≧ 1, the earthquake does not occur and the fault only slips slowly without an earthquake.