Landslide risk assessment in Italy: a case study in the Umbria-Marche Apennines

During the last years the Basin Authorities built the Landslide Risk Maps for the entire Italian territory. In accordance with the Italian legislation, four risk classes were defined on the basis of the expected damage or loss (negligible, mild, significant, severe) and of the potentially affected element (people, property, human activities and environrnental heritage). For risk assessment, reference was made to landslide hazard, which was assessed on the basis of the main morphometric and kinematic features, as well as of the activity distribution (according to Cruden & Varnes classification, 1996) of landslide movements. This paper reports the study of a training area aimed to develop a methodology for assessing the landslide risk on the basis of landslide movements characterization and of the definition of lithotechnical features. Risk areas were identified on the basis of guidelines established by Italian laws which have been enforced since 1989, often following major natural disasters. Particular emphasis was placed on the assessment of the activity of landslides, which gives insights into their probability of occurrence (hazard). In this sense, the multi-temporal analysis of aerial photos proved to be an effective investigating tool. The study also emphasised the importance of the choice of geomechanical properties as one of the primary factors of landslide susceptibility.