Viscoelastic simulation of earthquake cycle using a simple spring-dashpot-mass system with a friction law

We examine the viscoelastic effect on earthquake cycle using a simple sp ri ng-dashpot-mass system with a lab oratory-derived friction law. The tempora l change of the frictional stress is large at the early interseismic stage and gradually decreases, in contrast to the linear change in an elastic med ium. This temporal change depends on the Maxwell time. The smaller relaxati on time leads to the larger change of the stress accumulation rate. Such a rate change in stress accumulation may affect the seismicity at subduction zones. Moreover, we find that the smaller relaxation time produces the smal ler period of earthquake cycle and that, if the system relaxation time beco mes smaller than the period of earthquake cycle, the bifurcation phenomenon , where the period splits into two, occurs. It is also found that the small er relaxation time causes the earlier occurrence of the precursory stress d ecrease preceding the rapid stress drop.