Effects of time-dependent fluid pressure, off-fault damage, and compliant fault zones on dynamics of parallel strike-slip faults

We use a finite element dynamic code EQdyna to study the effect of off-fault plastic yielding, time-dependent fluid pressure change, and the existence of boarding fault zones on dynamics of two parallel strike-slip faults. With relatively weak off-fault yielding, we find the initiation of rupture on the second fault segment across the dilational step-over is slightly delayed, while the influence on the compressional one is minor. The existence of compliant fault zones allow the rupture to jump a wider compressional step-over (i.e., from 3 km to 4 km). The time-dependent fluid pressure change exerts a more profound influence than the above two factors. In particular, the time-dependent fluid pressure change and the existence of compliant fault zones allow rupture to jump dilational stopovers without any overlap along strike between two fault segments. In exploring schemes of more realistically gradual arrest of rupture in spontaneous rupture models, we find that a combination of increase in fault strength and decrease in stress drop works better than either of the two. Effects of gradual arrest of rupture on dynamics of parallel faults are under investigation.