Dynamic modeling of slow slip coupled with tremor

Abstract

[1] We theoretically study the generation mechanism of slow slip in a dynamical framework assuming a fault in a fluid-saturated thermoporoelastic medium; the fluid flow is taken into consideration. Dynamic slip is assumed to create pores and cause shear heating on the fault. Key parameters in the modeling are Su and Su′. The nondimensional parameter Su represents the relative dominance of the effect of pore creation on the fluid pressure change over that of shear heating, while Su′ is associated with the dominance of fluid flow effect over the effect of shear heating. Our calculation shows that we have to assume Su ≫ 1 and relatively small values for Su′ to simulate rupture speed that is negligibly small compared to the shear wave velocity. Although this was also found in our former paper, our new finding here is the simulation of slow slip coupled with tremor. We find that frozen slip is reactivated sporadically because the fluid inflow triggered by the pore creation elevates the fluid pressure on the fault. The slip reactivation actually occurs if Su′ is smaller than a threshold. Such sporadic reactivation of slips can be a model for slow slip coupled with tremor. We also show that the moment evolution curves are categorized into two separate groups when Su′ ≪ 0.1: one of them represents slow slips, while the other represents ordinary earthquakes.