Shear‐induced permeability anisotropy of simulated serpentinite gouge produced by triaxial deformation experiments

Abstract

AbstractWe have determined the permeability of antigorite serpentinite gouge in three orthogonal directions during frictional experiments using a triaxial gas apparatus to better understand fluid flow in subduction fault zones. The experiments were conducted at room temperature, a confining pressure of 150 MPa, a pore pressure of 100 MPa, and a constant slip rate of 0.58 µm/s. Although the initial permeabilities are similar in all directions, anisotropy develops during deformation, with the permeability normal to the shear plane becoming one order of magnitude lower than in the other directions when the shear stress reaches steady state. Formation of such permeability anisotropies may enhance fluid flow along the subduction plate interface and serpentinite‐bearing fault zones, important in evaluating potentially heterogeneous distribution of fluid pressure along the fault and in understanding the spatio‐temporal variation in the seismic activity.