Electrical resistivity surveys have been applied to geohydrology, geological mapping, geotechnical and archaeological prospecting and mineral deposits exploration (e.g., Keller and Frischknecht, 1966; Roy and Apparao, 1971; Zhdanov and
Keller, 1994; Urrutia-Fucugauchi, 1992; Loke and Barker, 1996a,b; Marin et al., 1998). Vertical electrical resistivity soundings (VES) have been used to investigate the underground structure and stratigraphy of sedimentary sequences in different geologic settings.