Uncovering the stabilizing and destabilizing roles of aseismic creep in earthquake rupture

Aseismic creep is widely recognized to influence earthquake rupture, but whether its role remains stationary in different earthquakes is poorly understood. In this study, we integrate GNSS/InSAR observations along the Xianshuihe fault in eastern Tibet and identify six aseismic creeping sections, which have been partially or fully involved in historical earthquakes. The creep exhibits spatiotemporal transient behavior. Using interseismic fault locking as a constraint, we performed 3D dynamic rupture simulations of the Xianshuihe fault. We demonstrate that aseismic creep exerts a dual role in earthquake rupture. On the stabilizing side, creeping sections terminate rupture propagation, with earthquakes that nucleate and are absorbed within the creeping zones further reinforcing their function as stable rupture barriers. Conversely, under favorable local stress conditions and modulated by transient aseismic slip migration and hypocenter location, creeping sections could promote rupture propagation, rendering their impact on rupture non-stationary in different earthquakes. These findings provide a plausible explanation for the pronounced variability of rupture segmentation and cascading on the geometrically simple Xianshuihe fault, and highlight the importance of incorporating both stabilizing and destabilizing effects of aseismic creep into seismic hazard assessments.