Simulation of the active and quiet periods of seismicity
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In this paper we simulate the repeated occurrence of strong earthquakes along a strike-slip fault by using a finite element model. The fault valve mechanism is included in the model in order to take into account the effect of pore fluid pressure variation. Five parameters are used to characterize the rheology of the fault, pore pressure variation, and fracture criteria. By systematically varying these parameters and calculating a large number of models we carried out a preliminary investigation on the alternatively quiet and active periods of seismicity and their relation to model parameters and loading conditions. Under the action of a constant-rate boundary movement, in the case of intermediate stress and pore pressure, the models display a regular quiescence-activity phenomenon with a cycle length of 1/3∼1 of the recurrence period. When the model is under high stress or high pore pressure, this phenomenon becomes irregular or inexplicit. When the model is subject to periodic boundary forces and the amplitude of force variation is not too small, it results in an alternatively quiet and active seismicity pattern with the same period of the force variation.
Key wordsearthquake model finite element method seismicity active period quiet period
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