Fault interaction reshapes seismic hazard of gaps in the Chinese mainland: a Coulomb stress perspective

The Chinese mainland resides in a tectonically complex setting shaped by multidirectional convergence of the Indian, Pacific, and Philippine Sea plates, resulting in frequent large earthquakes along active block boundaries. Stress perturbations from major events can either promote or delay subsequent ruptures through fault interactions. Here we present a continental-scale Coulomb stress framework that integrates 186 historical M ≥ 7 earthquakes—including coseismic and postseismic effects in layered lithospheric models—with fault-specific recurrence and stress-loading rates. The resulting metric, the Coulomb Stress-Modified Elapsed Rate (SER), quantifies how stress transfer advances or delays expected earthquake occurrence. Our results demonstrate that fault interactions substantially reshape the hazard state of many seismic gaps. Elevated seismic potential is identified in several key regions, including the Chuandian Block, the eastern Himalayan arc, the Qilian Block, the margins of the Ordos Block, and the North China Plain, where SER exceeds critical thresholds. These findings underscore the indispensable role of fault interaction in hazard assessment and provide a physically based, forward-looking framework for evaluating evolving seismic risk across the active block-boundary system of the Chinese mainland.