Fault slip induced by injection of water and pore fluid flow

The model experiments which simulated shear slip induced by injection of pore fluid have been conducted under triaxial compressive stress condition using a roughened bare fault. The objective is to understand characteristics of the induced slip behaviour, especially after the slip initiation obeying Coulomb failure criterion and pore fluid behaviour associated with the induced slip. Experimental results showed that intermittent slip occurred in all the injection-induced slip experiments. Moreover, it was also found that the pore fluid flow into the fault increased instantaneously accompanying with dynamic slip, which represents a part of higher slip velocity (V > 0.05 mm/s, V _max of 0.4 mm/s) in the intermittent slip. Quantitative estimation on the volume of the inflow of pore fluid during the dynamic slip suggested that a shear dilatancy would cause the instantaneous increase in pore fluid flow that occurred with the slip.