Valutazione della scuscettibilità e degli scenari di pericolosità e di rischio da frana in aree di interesse socio-economico (Calabria Settentrionale)

Abstract

Landslides are natural geologic processes that play a key role in landscape evolution, but represent also one of the most widespread natural hazard in Italian territory. In particular, many areas of the Calabria region (southern Italy) have been affected historically by mass movements, due to the combination of its peculiar geological, morphological, seismic and climatic features and frequently to regionally unsustainable land management. Landslides are responsible for direct and indirect damages, may cause loss of life and property, damages to natural resources and hamper infrastructure projects, by generating strong social and economic impacts. This resulting in millions of Euro per year in damages and restoration as well. Therefore, spatial identification of potentially unstable slopes and landslide risk evaluation are very important in order to get mitigation measures and for land planning. The aim of this study is landslide susceptibility and risk assessment in areas of socio-economic interest in Northern Calabria. Study areas were a section of the A3 highway and a part of Amendolara town. The identification and selection of study areas took into account topography, geology and urban development conditions for which the landsliding is potentially a problem. Landslide risk assessment in the section of A3 highway was performed in a qualitative way by overlapping the highway on the landslide susceptibility map; this had lead to the zonation of spatial risk which allowed an evaluation of the involvement of the highway in the different susceptibility areas. In the Amendolara territory risk assessment was carried out in a quantitative way according to the formula: Risk = Hazard × Vulnerability × Economic value of elements at risk (buildings and roads). Hazard was computed in a probabilistic way by means the product between spatial probability (probability that any given region will be affected by landslides), temporal probability (probability of occurrence of landslide events during time t) and probability of landslide size (probability that a landslide will have a certain size). Physical vulnerability was evaluated considering elements at risk features and landslide size. Finally, landslide risk was computed on the basis of economic value of elements at risk, pointing to the probability of money that can be lost at the occurrence of a landslide in a given area, in a certain interval of time and with a certain area. This study provides two case example for the qualitative and quantitative risk assessment which can be useful to planners and decision makers to identify areas where more damages are expected and that should receive priority in the use of limited resources directed to preventive plans to reduce the impact of the landslides.