PSI - Issue 44

Brunella Cutrone et al. / Procedia Structural Integrity 44 (2023) 713–720 Cutrone,Salvatore,Renzi and Tamasi / Structural Integrity Procedia 00 (2022) 000–000

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lack of protection and maintenance of the territory (ISPRA, 2021). The ongoing climate changes are also determining, in our latitudes, an increase in the frequency of intense rainfall events, and as a consequence an increase in the frequency of surface landslides and debris flows (Gariano and Guzzetti, 2016). The widespread outcrop of predominantly clayey lithotypes with poor mechanical resistance characteristics, especially in the presence of water, in fact contributes significantly to the unstable conditions of the slopes (Guzzetti, 2000). Moreover, the structural weakness of rock formations with rigid behavior is widely affected by faults and fractures. For the problem of landslides there was many actions taken to reduce the consequences. At the national level, the initiatives started with the management of the serious emergency generated in five municipalities of the Campania Region by rapid mudslides of high magnitude and speed which, on 5 and 6 May 1998, caused 160 victims and considerable economic damage. A little more than a month after the tragedy, Legislative Decree 180/98 was issued, the first legislative decree to explain the concept of risk in soil protection as a combination between the danger of a phenomenon with the value and vulnerability of the asset involved. The main objective of the legislative instrument was to quickly survey the hydrogeological risk situations present on the national territory in order to safeguard people and property, prevent an aggravation of critical conditions and take rapid action to reduce the risk itself. A few months later, in compliance with a series of legislative provisions specifically issued by the central government, the territorially competent bodies (Basin Authority of national and interregional importance and the regions for the remaining basins) were called, in a first phase, to approve extraordinary plans aimed at removing the highest risk situations (Italian Law N. 226, 1999) and, subsequently, to adopt Extract Plans for the Hydrogeological Asset (Italian Law 365, 2000). After the catastrophic event of the flow that took place on the Municipality of Sarno, the need to have a complete and homogeneous picture on the distribution of landslides on the national territory was strengthened, both as regards the archiving of information, and for the cartographic representation of the phenomena. For these reasons the Italian Landslide Inventory Project (IFFI, Inventario dei Fenomeni Franosi in Italia) was started. Funded by the Committee of Ministers for Soil Defense as per the provisions of Italian Law 183, 1989, it aims to identify and map landslides according to standardized and shared methods (Hervás et al.,2007). The inventory of landslide phenomena IFFI, made by Higher Institute for Environmental Protection and Research (ISPRA) and the Regions and Autonomous Provinces, provides a detailed picture of the distribution of landslides on the Italian territory. The landslides recorded are around 625,000 and affect an area of almost 24,000 km 2 , equal to 7.9% of the national territory (ISPRA, 2021, ISPRA, 2018). A picture of their distribution can be obtained from the landslide index, equal to the ratio between the landslide area and the total surface, calculated on a mesh with a 1 km side which can be observed in (Fig.1a), while in (Fig. 1b) shows the landslide index on a provincial basis.

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Fig. 1. (a) Distribution calculated on a mesh with a 1 km side, ISPRA,2021; (b) landslide index on a provincial basis, ISPRA,2018.