Landslide analysis in Apennine chain areas

The paper exposes the results of the study carried out in chain geological context where slopes, because of their lithology and local climate conditions, show to be historically affected by landsliding. The knowledge of the geologic context and of the geomorphological features characterizing an area represents the first step to identify the causes that led to landsliding and to describe its evolutive style. In geological chain areas, the physical properties and rock layering often facilitate slope instability and mass wasting. The study area belongs to the southern slope of the Peloritani Mountains (Sicily, Italy) and lies within the hydrographic basin of the Roccella torrent, an affluent of the Alcantara River. In this area, the slopes that are mainly constituted by flyschoid alternations tectonized during the formation of the Apennine–Maghrebian chain are affected by numerous landslides whose activity permits a detailed study of their evolution. The instability that characterizes the entire basin of the Roccella torrent is well represented by the complex rock slide–earth flow of Roccella Valdemone that has destroyed part of the village of the same name. The paper describes the last landslide event and suggests its previous evolutive history, along with the evolutionary tendency of the slope, through a comparison of several sections at a scale of 1:2,000 that was made on the topographic map carried out in 1970 and successively updated in 1990. Furthermore, the volume of mobilized rock and the erosion rate have been calculated from two different discrete element methods. The results are supported by borehole, seismic, and geoelectrical data confirming the analytical procedure’s validity, applied for complex landslides description, besides the acquisition of useful information for in situ investigation planning in analogous geological frameworks, where instability-induced phenomena are frequent and historical data are fragmentary or missing.