Fault deformation and movement under wide range of slip rates in boundary-value problem simulations

We implement various frictional constitutive laws for fault deformation and movement in the framework of the extended finite element method. Slip rates considered span from microns per second characteristic of fault creep, to meters per second characteristic of seismic slip speeds. For slow slip rates the frictional law is characterized by the regularized Dieterich-Ruina slowness law; for fast slip rates the frictional shear strength varies with the normal stress raised to the power 1/4, in accordance with melt lubrication theory. The extended finite element method allows the fault to pass through the interior of the finite elements, thus resolving the intense deformation without having to align the fault on the element sides. Casting the frictional constitutive laws in a boundary-value problem allows the investigation of the effect of variable coefficient of friction on fault rupture and propagation under traction, displacement, and mixed traction/displacement boundary conditions. In addition to the variable coefficient of friction models, we also implement a slip- weakening model within the extended finite element framework. We present two-dimensional plane strain simulations showing effects of slip rates on fault propagation and slip distributions under various traction and displacement boundary conditions.