A study of earthquake recurrence based on a one-body spring-slider model in the presence of thermal-pressurized slip-weakening friction and viscosity

Abstract

Earthquake recurrence is studied from the temporal variation in slip through numerical simulations based on the normalized form of equation of motion of a one-body spring-slider model with thermal-pressurized slip-weakening friction and viscosity. The wear process, whose effect is included in the friction law, is also taken into account in this study. The main parameters are the normalized characteristic displacement, Uc, of the friction law and the normalized damping coefficient (to represent viscosity), η. TR, D, and τD are the recurrence time of events, the final slip of an event, and the duration time of an event, respectively. Simulation results show that TR increases when Uc decreases or η increases, D and τD decrease with increasing η, and τD increases with Uc. The time- and slip-predictable model can describe the temporal variation in cumulative slip. When the wear process is considered, the thickness of slip zone, h, which depends on the cumulated slip, S(t)  =   ∑ D(t), i.e., h(t)  =  CS(t) (C is a dimensionless increasing rate of h with S), is an important parameter influencing TR and D. Uc is a function of h and thus depends on cumulated normalized slip, ∑ U, with an increasing rate of C. In the computational time period, the wear process influences the recurrence of events and such an effect increases with C when C  >  0.0001. When viscosity is present, the effect due to wear process becomes stronger. Both TR and D decrease when the fault becomes more mature, thus suggesting that it is more difficult to produce large earthquakes along a fault when it becomes more mature. Neither the time-predictable nor the slip-predictable model can describe the temporal variation in cumulative slip of earthquakes under the wear process with large C.