Triggering mechanism of aftershocks triggered by Wenchuan M_W7.9 earthquake

The analytic solution of earthquake triggering mechanism put forward by Dieterich has been widely used in quantitative analysis and description of regional seismic activities, and in the development of time-dependent earthquake prediction model. Based on the spring-slider model with a combination of rate-and-state-dependent friction, starting from the fault slip rate evolution equation proposed by Dieterich, we have derived the equation called clock advance/delay related to the earthquake faulting instability under the Coulomb stress perturbation. In comparison with the simple dislocation model, the current result suggests that the generation of earthquakes is actually related to the state of fault evolution. For the 2008 Wenchuan M_W7.9 earthquake sequence, we have estimated the possible time duration of aftershocks caused by main shock, both from theoretical inferring and empirical relation, and the result is similar to each other. Furthermore, two different stress change models have been used in the calculations of aftershock’s seismicity rate and cumulative number. These results suggest that the classic Dieterich stress change model could not fit the anomalous event increase well during a very short initial phase after the main shock, while the modified Dieterich model, which concerns the temporal variation of the fault shear stress rate, could be used to quantitatively describe the temporal evolution of aftershock decay.