A multi-disciplinary methodological approach to assess landslide risk

This analysis was carried out for the European community project "ALARM" (Assessment of Landslide Risk and Mitigation in Mountain Areas, 2002 - 2004) on landslide risk assessment in the municipality of Corvara in Badia, Italy. This mountainous area, located the Central Dolomites (Italian Alps), has a significant landslide hazard and a number of man-made and natural elements likely to be damaged by landslides. Three essential components for determining risk were analysed as an aid to preparedness and mitigation planning: event occurrence probability, assets at risk, and the vulnerability of these assets. A potential but "realistic" landslide hazard scenario was defined using available data and experts' knowledge; this step was followed by the identification of the potential vulnerable elements, and by an analysis of the social and economic activities that might be affected. A "cause-effect" correlation was applied, derived from the "dose-response" equation initially used in the biological sciences and then adapted by economists for the assessment of environmental risks. The relation was analysed from a physical point of view and the cause (the natural event) was correlated to the physical effects, i.e. the aesthetic, functional, and structural damage. Then an assessment of damages from a socioeconomic point of view was carried out, resulting in an evaluation of direct and indirect damages. It considered the assets in the exposed areas, tourist flows, goods transport and the effect on other social and economic activities. The research shows the importance of indirect damage in the determination of the socioeconomic consequences. It is strongly influenced by the role of the activities involved in the social equilibrium. Among the main applications of risk analysis are to help choose the best prevention and mitigation options and help to decide how to allocate resources properly, so that potential benefits are maximised at an acceptable cost.