Grandi frane e deformazioni gravitative profonde di versante della Calabria. Note illustrative della carta al 250.000

Large-scale landslides and deep-seated gravirational slope deformations (dgsd) are frequent in the Calabrian territory, where they cover ca. 2 % of the territory surface (300 km2). In the 1:250,000 scale Map of Large- scale Landslides and Deep-Seated Gravitational Slope Deformations of Calabria (fold-out plate, referred to as the «Map» from here in the text) have been mapped phenomena with at least one side equal or exceeding 500 m. Large-scale landslides are landslides whose size is determinant in regard to the development of the phenomenon, or in regard to the intervention feasibility. They include scale-effect landslides, whose deformation mechanism is modified by scale effects that influence mechanical properties of deforming rocks (e.g. the friction reduction in large rock avalanches). Deep-seated gravitational slope deformations (dgsd) are slope movements for which it is not essential postulating the presence of a continuous shearing surface. Their mechanism can be modified by scale factors (e.g. the brittle-ductile transition in creep deformation). The mapping base consists of the topography with contour lines cities and lifelines, and of the lithology. Lithologic units are characterized by their mechanic behavior in relation to the studied phenomena, thus they can be considered as Litho-Technical Units (LTU). In the Map, all units have been grouped into eight LTU, herein ordered according to the slope movement increasing frequency. 1 - Carbonates. It includes thick Mesozoic-Paleogene limestones and dolostones in the Northern Calabria and Jurassic limestones covering crystalline allochtonous nappes in South Calabria. Faulting and jointing from rare to extremely frequent (shattered dolostone). 2 - Paleozoic, medium to high-grade metamorphim and igneous rocks. It includes different t3?pes of gneiss and rocks of the granite family forming thick allochtonous nappes emplaced during Middle-Upper Miocene. Jointing and weathering intensive. 3 - Neogene hard sedimentary rocks. It includes sandstones, conglomerates, limestones banks, with layers of softer rocks. They were deposited in different sedimentary cycles (Lower Miocene, Tortonian-Messi-nian, Messinian-Lower Pliocene). Jointing from rare to frequent; weathering moderate. 4 - Pliocene and Pleistocene soft marine and continental deposits. They include sand, clay and subordinate gravel thick beds that fill the tectonic depressions. Faulting and folding moderate, locally intensive . 5 - Mesozoic, ophiolite-bearing low to medium grade metamorphic rocks, derived by the metamorphism of basic lavas with silicanch limestones of the old Tyrrhenian oceanic crust. They include three tectonic units emplaced during Upper Miocene. Tectonic structures (principally multiple duplex and joints) are pervasive and frequent to very frequent. 6 - Tertiary (Messinian-Lower Pliocene) clayey and marly terranes with evapontic levels. It is a heterogeneous unit made of relatively thin levels with very different lithologic nature, so that the proprieties of the unit essentially depend on the weakest beds. Jointing sand folding from moderate to intensive. Gypsum levels heavily attacked by karst erosion. 7 - Paleozoic and Mesozoic very low to low grade metamorphic rocks. They include essentially slates and phyllitic rocks of oceanic and continental crust, arranged in tectonic nappes piled up in Middle Miocene. Jointing and weathering intensive. 8 - Mesozoic and Tertiary flyschs. They include the Mesozoic quartzi-tic flysch of the north-eastern Sila mountains the MesozoicTertiary flyschs of the north-eastern Calabria, and the Cretaceous-Oligocene Varicolored shales cropping along the Ionian side of the region. Tectonic deformation from intensive to extremely intensive. Major tectonic structures which gene