Urban-Scale Risk Assessment of Rainfall-Induced Rock-Slope Instabilities: The Case Study of Popoli Terme (Abruzzo, Italy)

Abstract

Rainfall-induced rock-slope instabilities threaten urban areas and infrastructure set at the foot of steep slopes. Urban-scale hazard appraisal is essential for risk estimation, prevention and emergency planning. Within this framework, the Italian SLIDE project, together with the MULTI-TWIN project, provides an integrated hydrogeological and seismic hazard assessment by combining literature and newly acquired data. We present the urban-scale hazard and risk assessment of rainfall-induced rock-slope instabilities in the municipality of Popoli Terme (Abruzzo, Italy). The methodology fuses datasets and performs quality control; statistically models boulder-detachment areas; performs 3D simulations of trajectories, kinetic energy, and runout; and derives building-level vulnerability and risk. Hazard, vulnerability, and risk maps are available within the MULTI-TWIN platform to support urban planning. The maps highlight the buildings most exposed to rainfall-triggered rock-slope instabilities. The same platform provides final multi-risk maps by combining independent natural hazards (seismic, hydraulic, and hydrogeological) at both the building and urban scales. The risk is expressed as expected economic loss per square meter to guide local mitigation and prevention policies.