GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 3.2 ___ GNGTS 2023 MG array combines a good signal strength needed in extremely high conductive environments, like the coastal ones, with a good resolution and depth of investigation. ERT/TDIP data were inverted using the VEMI software (De Donno and Cardarelli, 2017), suitably integrated to perform a full-decay inversion for Cole-Cole parameters, re-parameterized through the direct-current (DC) conductivity , the maximum imaginary conductivity , the relaxation time τ and the σ 0 σ '' frequency exponent c, following the approach after Fiandaca et al. (2018). From the results of the full-decay TDIP inversion, we can predict the intrinsic permeability k (in m2) through the correlation after Weller et al. (2015), suitable for a wide range of unconsolidated sediments with similar lithology to those retrieved in the study area. The MASW acquisition was carried out using max. 48 (4.5 Hz) vertical geophones Rayleigh waves) and (7.5 Hz) horizontal geophones at (Love waves) spaced 2 m apart. The sampling interval was 0.125 ms, for a trace length of 2.048 s. The center of the MASW survey coincides with the center of the ERT/TDIP line. Shots were fired with a 7 kg sledgehammer stricken vertically on a metal plate for generating Rayleigh-waves and horizontally on a lightweight aluminum source in opposite directions for Love waves, with offsets of 2, 4 and 8 both from the first and the last geophone (1-4 stacks). Field data were preliminarily processed using the open-source Geopsy software (Wathelet et al., 2020) and the dispersion curves (both for Rayleigh and Love waves) were inverted for shear-wave velocity ( vs ) using the Dinver module of Geopsy. Results The results are shown in Fig. 2, where the mean vs model resulting from the inversion of MASW data (black solid line) and the groundwater level logged in P1 (white area) are superimposed to the ERT/TDIP models ( , e c in Fig. 2a, 2b e 2c respectively) and to the permeability section σ 0 σ '' in Fig. 2d.