Weathering in the crystalline rocks of Calabria, Italy, and relationships to landslides

This paper reviews approximately 40 years of studies focused on landslides in weathered crystalline rocks of Calabria, southern Italy. In these studies geological, geomorphological, mineralogical, petrographical, engineering-geological and geotechnical aspects of the Palaeozoic granitoids and the high-grade metamorphic rocks cropping out in the Calabrian massifs have been considered. This in turn has allowed depiction of the regional landsliding scenario, where almost all the main typologies of mass movements have been recognized, ranging from shallow soil slips and extremely rapid debris flows to slow moving deep-seated gravitational slope deformations. From north to south, the Sila Massif, Coastal Chain, and Poro, Serre and Aspromonte Massifs are described, with reference to the studies dealing with weathering and slope movements in the different geological and morphological settings. The regional extent of the weathering processes gave researchers the opportunity to adopt and calibrate mapping methods, specifically devoted to analysis and mitigation of the landslide hazard in weathered materials, which have also been applied to important civil engineering works. A further distinctive character of the Calabrian weathering is its age, which has been ascribed to Tertiary time. Such an ancient initiation could be regarded as one of the main reasons for the depth of the weathered mantle, which, despite the rugged topography, in some districts exceeds 150–200 m