Thermo-poro-mechanical properties of clayey gouge and application to rapid fault shearing

In this paper, the mechanism of fault pressurization in rapid slip events is analysed on the basis of a complete characterization of the thermo-poro-mechanical behaviour of a clayey gouge extracted at 760 m 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 vapourization. Copyright (c) 2006 John Wiley & Sons, Ltd.