Assessment of seismic disaster risk in the Dingri earthquake based on fault-induced ground motion effects

Accurate and efficient seismic disaster risk assessment is essential for disaster prevention and emergency response, yet current approaches often inadequately integrate multiple drivers and capture spatial heterogeneity in active tectonic zones. This study proposes a three-dimensional coupling framework integrating subsurface structure, surface environment, and building characteristics using multi-source remote sensing and detailed field investigations. The results show that fault dynamics strongly control risk differentiation: hanging-wall areas exhibit 42.6% higher comprehensive risk than footwall regions (p < 0.05), and mortality risk increases sharply within 200 m of active faults (OR = 3.17, p < 0.01), reflecting the combined effects of fault properties, topography, and site conditions. Geomorphological conditions and structural vulnerability jointly amplify disaster impacts; vulnerable civil structures account for 91.31% MMI IX zones, contributing to pronounced spatial variability in mortality. An optimized village-level model achieves high predictive performance (R² = 0.7494) and reproduces observed mortality patterns. Overall, the findings highlight fault-related asymmetry (hanging wall/footwall effects) and ground-motion amplification mechanisms in shaping casualty patterns, providing a scientific basis for targeted risk mitigation in active fault zones. Future work will incorporate InSAR deformation monitoring and geotechnical investigations to refine fault micro-mechanics and develop dynamic risk models.