A Monitoring System for Mitigation Planning: The Case of "Bagnaschino" Landslide in Northern Italy

Abstract

Problem statement: The Bagnaschino landslide occurred in November 1994 that caused extensive floods and many landslides all over northern Italy. In southern Piedmont, the Casotto River (Cuneo Province) damaged many kilometers of provincial road and the river was dammed by this landslide. The landslide involves an area of about 100 thousands m³, but a good knowledge of the landslide is however still missing because of the complexity of the phenomenon. Approach: The aim of this study has been to collect and reorganize available data with the georeferencing in a GIS project of the information taken from investigations of the last years. An electric tomography and seismic reflection were carried out above the landslide body to enrich the available data. The final goal has been to well-know the sliding surfaces and the different processes involved in the slope deformation. Results: The research has redefined the geological base model, that was been the local stratigraphy is represented by an heterogeneous deposit of loose materials (20-30 m), with abundant silty-clayey matrix. The bedrock is composed by fractured micashists, metabolites and green stones. The landslide has shown many surfaces of movement at different depths and continuous reactivations, but the triggering mechanism is still not clarified due to the complex geological setting. Conclusion: Rock masses observed in correspondence of the road and the river bed has suggested that the main sliding surface did not involve the lower part of the slope and that the road is built on stable bedrock. The intention will be to continue the monitoring of the landslide in order to give to the Local Authorities the correct instruments for planning mitigation projects.