From landslide characterization to nature reserve management. The “Scialimata Grande di Torre Alfina” landslide geosite (central Apennines, Italy)

Italy is characterized by widespread geomorphological instability, among which landslides leave impressive marks on the landscape. Nevertheless, landslide bodies may represent key sites for thematic and educational itineraries, especially in protected areas, where their management becomes an important issue. Our study focuses on the “Monte Rufeno Nature Reserve” (Central Apennines, Italy), where iconic landslides are present. Here, the “Scialimata Grande di Torre Alfina” landslide (SGTA) is listed in the regional Geosite database. This work aims to propose a multiscale procedure for landslide analysis, in terms of both hazard sources but also educational and geoheritage enhancement opportunities in natural reserves. After performing a Landslide Susceptibility conditional Analysis (LSA) for the reserve territory, attention was focused on the SGTA, to define properly its features and morphodynamics. A multi-disciplinary approach was adopted, by applying both remote sensing (UAV structure from motion, Photointerpretation) and field survey (geomorphological and GPS monitoring). From the LSA, based on drainage density, curvature, and slope triggering factors, the road and trail susceptibility maps were derived, as base tools for future risk assessments and trail paths management within the reserve. At the SGTA scale, the monitoring showed a displacement of up to 23 m during the time interval between 2015 and 2018. The landslide dynamics seem to be driven by alternating dry and extremely wet periods; moreover, leaks from the aqueduct in the detachment area and piping effects through clays may have also decreased the substrate cohesion. The SGTA complex influence on the Paglia River valley geometry was also hypothesized, underlining the action of landslide through different spatial scales (on-site and off-site) and on different environment features (sediment connectivity, hydrology). Finally, the SGTA appears highly representative of the geomorphic dynamics within the Nature Reserve (i.e., scientific value) and it could be classified as an active geosite. Since the site was featured by a tourist trail, adequate management strategies must be adopted, considering the educational value and safety issues.