Effects of subducted seamounts on shallow slow slip events within seismogenic zone

Abstract:

Shallow slow slip events (SSEs) within seismogenic zone have been increasingly reported to be related to subducted seamounts, which may strengthen and weaken the fault. Investigating the mechanism of seamounts in favoring shallow SSEs provides important insights into fault slip. We report here that shallow SSEs can both occur in the low-stress and high-stress seamount area by numerical studies incorporating rate-and-state friction law in a two-dimensional subduction zone model. By changing the seamount location, width, and stress perturbation, periodic SSEs are found under extremely low stress. In the cases of fault strengthening, single SSE occurs in different stages of seismic cycle. Seamounts location plays a key role in SSEs occurrence and is inversely related to the critical stress increases. We suggest that subducted seamounts induced strength heterogeneity may be a common mechanism for shallow SSE within seismogenic zone.