Analysing physical vulnerability and risk of historical religious buildings to earthquake-triggered landslides

Landslides pose a significant and increasing threat to human-valued assets worldwide. The risk-based paradigm enables efficient management of the physical and non-physical elements of human and natural systems. Physical vulnerability quantifies the expected degree of loss or damage to a specific category of vulnerable elements resulting from their physical interaction with a hazardous event. Its estimation is central to quantitative risk analysis. Seismically induced landslides pose a relevant threat in many parts of the world, including areas hosting high-valued cultural heritage such as religious structures. The quantitative estimation of the physical vulnerability of historical churches to seismically induced landslides has received limited attention in the literature. This paper advances research on this topic by developing a novel index-based methodology relying on landslide intensity and the structural characteristics of churches. The proposed methodology is applied to 71 historical churches located in an area characterised by strong seismicity and frequent slope instability in north-western Tuscany, central Italy. Calculated vulnerability indices are combined with landslide hazard (susceptibility) and exposure (number of buildings located in the study area) to provide quantitative, regional-scale risk estimates. This approach provides useful criteria for landslide risk management in the form of landslide susceptibility zonation and physical risk.