“…The parameter μ 0 is the reference static friction coefficient, θ denotes the evolving state variable with the aging evolution law and V p is the plastic slip rate defined by where W denotes the thickness or width of the fault zone in the continuous host rock. Following van Dinther, Gerya, Dalguer, Mai, et al () and Herrendörfer et al () we define W =Δ x , where Δ x is the numerical grid size. We use this approximation because in classical applications of plasticity the deformation localizes to within 1–2 grid cells (e.g., Lavier et al, ; van Dinther, Gerya, Dalguer, Corbi, et al, ).…”