Thermal imaging on simulated faults during frictional sliding

TL;DR

This study investigates heat dissipation during frictional sliding on simulated faults, revealing localized heating linked to surface deformation, which could influence earthquake weakening mechanisms.

Contribution

The paper introduces laboratory experiments analyzing heat emission and surface evolution during fault sliding, highlighting the role of asperities and gouge in heat generation.

Findings

Localized heat spots correlate with plastic deformation.

Adding gouge results in more diffuse heating.

Strong asperities produce concentrated heat and potential nucleation sites.

Abstract

Heating during frictional sliding is a major component of the energy budget of earthquakes and represents a potential weakening mechanism. It is therefore important to investigate how heat dissipates during sliding on simulated faults. We present results from laboratory friction experiments where a halite (NaCl) slider held under constant load is dragged across a coarse substrate. Surface evolution and frictional resistance are recorded. Heat emission at the sliding surface is monitored using an infra-red camera. We demonstrate a link between plastic deformations of halite and enhanced heating characterized by transient localized heat spots. When sand 'gouge' is added to the interface, heating is more diffuse. Importantly, when strong asperities concentrate deformation, significantly more heat is produced locally. In natural faults such regions could be nucleation patches for melt production and hence potentially initiate weakening during earthquakes at much smaller sliding velocities or shear stress than previously thought.