Thermo-Poro-Mechanical Properties of Clayey Gouge and Application to Rapid Fault Shearing

TL;DR

This study investigates the thermo-poro-mechanical behavior of clayey fault gouge, revealing how thermal collapse and fluidization can influence fault pressurization during rapid slip events, with implications for seismic activity.

Contribution

It provides a comprehensive characterization of clayey gouge behavior under fault conditions, highlighting the role of thermal collapse and ultra localized zones in fault fluidization.

Findings

Thermally collapsible clayey gouge can cause effective stress reduction.

Ultra localized zones control pore pressure and temperature dynamics.

Fluidization of fault gouge influences fault slip behavior.

Abstract

In this paper, the mechanism of fault pressurization in rapid slip events is analyzed on the basis of a complete characterization of the thermo-poro-mechanical behavior of a clayey gouge extracted at 760m depth in Aigion fault in the active seismic zone of the Gulf of Corinth, Greece. It is shown that the thermally collapsible character of this clayey gouge can be responsible for a dramatic reduction of effective stress and a full fluidization of the material. The thickness of the 'ultra localized' zone of highly strained material is a key parameter that controls the competing phenomena of pore pressure increase leading to fluidization of the fault gouge and temperature increase leading to pore fluid vaporization.