This paper analyzes the effects of pore pressure rate for a spring -
block system that is a simple model of a laboratory experiment. Pore
pressure is increased at a constant rate in a remote reservoir and slip
is governed by rate and state friction. The frequency of rapid slip
events increases with the increase of a nondimensional pressure rate
that is the ratio of the time scale of frictional sliding to that for
pressure increase. As the pressure rate increases, the more rapid
increase of pore pressure on the slip surface quickly stabilizes slip
events due to rate and state friction. Rate and state and pressure rate
effects interact in a limited range of pressure rate and diffusivity.
This range includes pressure rates and diffusivities representative of
recent laboratory experiments.