GNGTS 2022 - Atti del 40° Convegno Nazionale

446 GNGTS 2022 Sessione 3.2 HIGH RESOLUTION ELECTRICAL RESISTIVITY TOMOGRAPHY TO DETECT SUBSOIL WATER SEEPAGE IN LANDSLIDES INVOLVING CLAY SLOPES D. Barbero 1 , A. Maroni 2 , M. Naldi 3 , S. Peyrot 4 , E. Veronese 5 1 Geological, Geotechnical and Geophysical Office of Dr. Diego Barbero, San Martino Alfieri (AT), Italy 2 Geology Student, University of Turin, Italy 3 Techgea s.r.l., Torino, Italy 4 Geologist, Freelance professional, Torino, Italy 5 Laboratorio Accreditato Analisi Ambientali Arcadia s.r.l, Tromello (PV), Italy Introduction. The Electrical Resistivity Tomography (ERT) is a useful tool to define not only the shallow subsurface stratigraphy of complex geological area involved by landslides, but also to locate in clay soils underground water seepage. In active landslides, the identification of layers of saturated clays in slopes forming the sliding surface, is of primary importance to optimize emergency actions first and then the final design of the slopes stabilization, with a relevant cost saving. Previous researches about the combination of different geophysical surveys with geotechnical tests on subsoil characterization (see Barbero and Naldi, 2018a; Barbero and Naldi, 2018b; Barbero et al. , 2020) highlighted not only a better comprehension of the failure mechanisms of unstable slopes, but also a correct interpretation of environmental issues in support of environmental geology. In this short note, we report on two case histories of geophysical investigation by means of hight resolution Electrical resistivity tomography surveys of landslide bodies located in the southern Piedmont (Asti Province) shaped in the same litotype (Lugagnano Clay). Geological context. The investigated areas are located in the western side of the Asti Reliefs (elevation 130-320 m a.s.l.) in the central Piedmont hilly region (Fig. 1). The sedimentary Fig. 1 - Schematic geological and structural map of southern Piedmont region (RFDZ: Rio Freddo Deformation Zone; TTDZ: Torrente Traversola Deformation Zone) (after Forno et al. , 2015).