Thermo-poro-mechanical properties of the Aigion fault clayey gouge-application to the analysis of shear heating and fluid pressurization

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 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. Moreover a back analysis of an existing slip surface inside the clayey core of the fault shows that this failure plane is compatible with principal stress directions locally parallel and perpendicular to the fault axis.