Fault‐zone healing effectiveness and the structural evolution of strike‐slip fault systems

SUMMARY Numerical simulations of long‐term crustal deformation reveal the important role that damage healing (i.e. fault‐zone strengthening) plays in the structural evolution of strike‐slip fault systems. We explore the sensitivity of simulated fault zone structure and evolution patterns to reasonable variations in the healing‐rate parameters in a continuum damage rheology model. Healing effectiveness, defined herein as a function of the healing rate parameters, describes the post‐seismic healing process in terms of the characteristic inter‐seismic damage level expected along fault segments in our simulations. Healing effectiveness is shown to control the spatial extent of damage zones and the long‐term geometrical complexity of strike‐slip fault systems in our 3‐D simulations. Specifically, simulations with highly effective healing form interseismically shallow fault cores bracketed by wide zones of off‐fault damage. Ineffective healing yields deeper fault cores that persist throughout the interseismic interval, and narrower zones of off‐fault damage. Furthermore, highly effective healing leads to a rapid evolution of an initially segmented fault system to a simpler through‐going fault, while ineffective healing along a segmented fault preserves complexities such as stepovers and fault jogs. Healing effectiveness and its role in fault evolution in our model may be generalized to describe how heat, fluid‐flow and stress conditions (that contribute to fault‐zone healing) affect fault‐zone structure and fault system evolution patterns.