GNGTS 2022 - Atti del 40° Convegno Nazionale

GNGTS 2022 Sessione 3.2 447 succession is defined, in the lower bands of the hilly reliefs, by deep marine clay deposits (Lugagnano Clay) and littoral sandy deposits (Asti Sand) referred to the Pliocene (Zanclean). These sediments are usually covered by the “villafranchian succession” comprising deltaic deposits (Lower Complex) and fluvial deposits (Upper Complex), referred to the Piacenzian and Calabrian respectively, separated by an unconformity (Cascina Viarengo Surface) (Carraro Ed, 1996; Forno et al. , 2015). Above these sediments a widespread silty and subordinately gravelly fluvial cover of middle and upper Pleistocene occurs (Carraro and Valpreda, 1991). The fluvial deposits appear as a terraced fluvial succession that develops at different heights at the top of the hill ridges in the Asti Reliefs frequently involved by surficial landslides (mudflows) (Barbero et al. , 2014a; Barbero et al. , 2014b). The whole sedimentary sequence is deformed by the Asti Syncline consisting of a wide E-W regional scale fold developed in the central hilly area (Poirino Plateau, Asti Reliefs and Alessandria Plateau) (Fig. 1). Recent geological researches (Forno et al. , 2014; Gattiglio et al. , 2015), regarding the Plio-Pleistocene evolution of the western edge of the Asti Reliefs, emphasized the presence of a N-S deformation zone, named T. Traversola Deformation Zone (TTDZ). This structure corresponds to a scarp with, a rectilinear trend in map view, a height up to a hundred meters and a length of about 30 km, delimiting the Asti Reliefs from the Poirino Plateau. Landslide in San Damiano d’Asti village case study. Geological and morphological setting. Detailed geological and morphological surveys have been carried out (Barbero et al. , 2015). The investigated side is located in the lower band of a hilly ridge gently sloping towards SSW ( A in Fig. 2). The landslide involves a slope shaped in the marine succession formed by gray-blue Fig. 2 - Landslide section profile and re-profiling design with ERT location (above), Geoelectrical tomography section (below).