STABILITY OF SLIP IN ELASTIC SYSTEM USING AGEING AND SLIP LAWS

Abstract

Earthquakes are the culmination of a friction-mediated slip instability on natural fault systems. The weakening of the interface during the phase of accelerating slip is determined by the frictional properties of the sliding surface. In the absence of in situ constraints on the physics of friction on natural faults, laboratory experiments have guided the design of relevant constitutive equations. Rate and state friction is the most widely used representative of this class of friction theories. Unfortunately, the widely used ageing with one state variable and slip laws are both incapable of explaining the whole range of rock friction experiments. Our work explores the possibility that two state variables can describe the whole range of rock friction behaviour in the laboratory. We undertake a numerical analysis to study the behaviour of a single degree of freedom system employing a two state variable constitutive law. We focus on the numerical behaviour of an aging state variable coupled to slip state variable. We study the numerical response of this constitutive law under typical laboratory velocity step and slide-hold-slide experiments. In particular, we observe the ratio of slip distances for aging and slip laws.