On the use and effectiveness of the Italian Landslide Hazard Map for the assessment of the Landslide Class of Attention according to the Italian Guidelines for classifying the risk of existing bridges

In the last three years the Geotechnical and Geological team of the University of Pisa, as member of the FABRE Consortium, provided a technical and scientific support to the first experiences of application of the new Italian Guidelines for classifying the risk of existing bridges (LLG). This contribution deals with the landslide risk and will be focused on the use and effectiveness of the Italian Landslide Hazard Map (LHM) for the assessment of the Landslide Class of Attention. LLG are based on a multi-level approach. In the Level 0 some basic landslide risk information of the area in which the considered bridge is located are collected, while in the Level 1 a visual inspection is performed and in the Level 2 the Landslide Class of Attention is evaluated. On several occasions, geological and geotechnical data are not directly available in the project documentation of the bridge, thus, the only available data for a preliminary screening (desk-study) of the study area come from some National Geo-databases in which the information have been generally organized and developed for different purposes. In Italy, the most relevant maps for identifying the areas interested by recognized or potential landslides are distributed by the ISPRA Institute. The ISPRA LHM uses for the entire Italian territory 5 hazard classes: PF1 (moderate), PF2 (medium), PF3 (high), P4 (very high) and AA (Area of Attention). This Map is the result of the activities performed by all the District Basin Authorities which provide to ISPRA the data related to the landslide hazard areas. Nevertheless, each District Basin Authority uses its own method (qualitative, quantitative, geomorphological or hybrid methods) for the assessment of landslide hazard. As a result, the final LHM might be affected by some inhomogeneities. This contribution will present and discuss a first application of the Italian LHM in the assessment of the Landslide Class of Attention for a representative sample of bridges.