Rupture-induced dynamic pore pressure effect on rupture

Abstract

The ordinary elasticity model is often used in dynamic rupture earthquake simulation without incorporating the poroelasticity effect in rocks. In consideration that rocks are porous and saturated, we carry out a two-dimensional simulation of spontaneous rupture in a poroelastic medium with a finite difference time domain scheme. In particular, the influence of the rupture-induced pore pressure on the rupture process is investigated. The fault plane is idealized as an impermeable layer of negligible thickness, and the rupture is assumed to be governed by the slip-weakening friction law. Results show that an impermeable fault plane leads to a rupture-induced pore pressure change, which promotes or hinders the rupture process by altering effective normal compressive stress (normal compressive stress minus pore pressure). It is remarkable that super-shear rupturing will occur when the porosity of the rock around the fault increases to some extent. The comparison with the permeable fault model suggests that the permeability of the fault and the porosity of rocks around the fault significantly influence the dynamic rupture process.