Frictional state evolution laws and the non-linear nucleation of dynamic shear rupture

TL;DR

This paper investigates whether a characteristic length scale for slip instability exists in frictional systems, revealing that it often does not, which impacts understanding of earthquake nucleation and the nature of frictional strength.

Contribution

The study demonstrates that a characteristic length for slip instability is not always present, challenging previous assumptions and linking rupture nucleation to frictional strength evolution.

Findings

Characteristic length often does not exist for realistic friction laws.

Small area can support slip instability under certain friction laws.

Nucleation phase contains information on frictional strength evolution.

Abstract

We assess if a characteristic length for a non-linear interfacial slip instability follows from theoretical descriptions of sliding friction. We examine friction laws and their coupling with the elasticity of bodies in contact and show that such a length does not always exist. We consider a range of descriptions for frictional strength and show that the area needed to support a slip instability is negligibly small for laws that are more faithful to experimental data. This questions whether a minimum earthquake size exists and shows that the nucleation phase of dynamic rupture contains discriminatory information on the nature of frictional strength evolution.