Spatiotemporal Slip Deficit Around the Locked Patches Within the Vertical Strike‐Slip Fault Arising From Viscoelastic Rheology: Implications for the Seismic Hazard Assessment

ABSTRACT Investigating how locked patches hinder sliding in adjacent regions along strike‐slip faults is crucial for understanding fault coupling distribution. We develop a 3‐D viscoelastic finite element model integrating a vertical strike‐slip fault with locked patches to investigate spatiotemporal interseismic coupling (ISC). The ISC ≥ 0.8 enclosed zone remains nearly constant, while other partial coupling zones expand due to viscoelastic effects. The ISC = 0.8 zone, typically indicative of strong coupling zones, tends to overestimate the locked patch by up to 1.8 times. Significant seismic moment deficits accumulate outside the asperity, dominantly influencing the full seismic moment deficit rate. Viscoelasticity further dilates the partially coupled zone, contributing to an increasing seismic moment deficit over time. This study highlights the potential of the binary coupling approach, assuming viscoelasticity, to simulate interseismic deformation and assess the seismic hazard.