Pluviometrical events and slope stability on weathered and degraded rocks (Acri, Calabria, Italy).

The recent activity ofthe "Serra di Buda" landslide near the town of Acri suggested to verify and improve a methodology to characterise rainfalls which could trigger slope instabilities. The landslide, already active in the past, involves weathered ami/or degraded gneissic and granitic rocks. An historical research allowed to individuate many dates concerning slope instabilities induced by rainfalls near Acri. The study used different hydrological analysis techniques to individuate pluviometrical scenarios of landslides with shallow, medium deep and deep failure surface: the first ten critic cases were individuated and compared with historical dates for each hydrological analysis technique using daily rainfalls. The historical research has been completed by the geomorphological characterisation of the landslides near Acri and repeating the comparisons. This study permits to individuate the periods in which the historical research could be improved and the values of the parameters able to characterise pluviometrical instability scenarios.