GNGTS 2013 - Atti del 32° Convegno Nazionale

APPLICATION OF ELECTRICAL RESISTIVITY TOMOGRAPHIES FOR THE GEOELECTRIC CHARACTERIZATION OF MONTAGUTO LANDSLIDE (Southern Italy) G. Calamita 1 , A. Perrone 1 , J. Bellanova 1 , A. Giocoli 2 , V. Lapenna 1 , R. Luongo 1 , S. Piscitelli 1 1 Institute of Methodologies for Environmental Analysis (IMAA-CNR), Tito Scalo (PZ), Italy 2 Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Rome, Italy Introduction. This paper reports the results of a geoelectrical survey carried out on the Montaguto landslide, located in the Apennine Chain (Campania Region, Southern Italy) (Fig. 1). Montaguto landslide is an earthflow and it is considered one of the larger and complex mass movements in Europe, with a length of about 3 x 10 3 m, an estimated volume of displaced material of about 4-6 x 10 6 m³ and a sliding surface depth varying from 5 m, near the center, to 20-30 m, at the toe. Its areal extension is about 6.6 x 10 5 m 2 (~66 ha), whereas its width ranges between 45 and 420 m (Ventura et. al., 2011; Giordan et al. , 2013; Guerriero et al. , 2013). As stated by Ventura et al. , (2011), the depth of the water table roughly corresponds to the thickness of sliding material with sag ponds occurring in the upper and central zone. The altitude gap between the head scarp, 830 m a.s.l., and the toe, 420 a.s.l., is about 420 m (Giordan et al. , 2013). The earth-flow has been active for almost 60 years starting from, at least, 1954. Long periods of relatively slow movement and shorter periods of relatively rapid movement periodically follow one another in the earth-flow activity (Guerriero et al. , 2013). In the mid spring season 2006 began the most extensive reported slope failure, when an estimated volume of 6 x 10 6 m 3 earthflow activated. Four years later, in the spring of 2010, the earth-flow reached the Cervaro River valley, obstructed and strongly damaged the strategic rail corridor infrastructure connecting the Tyrrhenian and Adriatic coasts of Italy and the National Road SS90, that connects Naples to Foggia (Ventura et al. , 2011; Guerriero et al. , 2013). The reported velocities of most movement, from 1954 to 2010, ranged from 1 – 2 mm/ month to 2 – 5 cm/day. A sharp increase was registered during the large mobilization in both 2006 and 2010, from 1 m/day to 1 m/hour, as reported by Guerriero et al. (2013), or 5 m/day, as reported by Giordan et al. (2013). Fig. 1 – Location of the Montaguto earthflow, Campania, southern Italy. (A) 3D view. Red line: landslide boundary. White dashed line: Rio Nocelle catchment divide. Black line: SP90 provincial road. Violet line: railroad. Blue line: Cervaro River (from Giordan et al. , 2013). 97 GNGTS 2013 S essione 3.2