GNGTS 2018 - 37° Convegno Nazionale

674 GNGTS 2018 S essione 3.2 layer, visible only in the left part of the section, because of the maximum depth of 10m that is reached by the SRT inversion. The map of the cross-gradients function (Fig. 3c) obtained from the ERT and SRT inverted models and calculated using the forward difference scheme with uniform discretization, exhibits a few areas of structural difference in the left part of the section, with values around zero in the most of the section. The scatter-plot (Fig. 3d) shows a certain dispersion of data, typical of field data, which are affected by some errors. The joint inversion was conducted using the lambda values and the same conditions of the separated inversion, choosing the λ CG value as the minimum mean value of the cross-gradients vector and specifically 1200 (Fig. 2c). The convergence was reached after 5 iterations. ERT map is very similar to the one obtained by the separated inversion (Fig. 3e), while the Fig. 2 - a) L-curve for ERT data; b) L-curve for SRT data; c) Graph of the mean value of the cross-gradients function for the field data. Fig. 3 - a) ERT map obtained from the separated inversion; b) SRT map obtained from the separated inversion; c) Map of the cross-gradients function for the separated inversion; d) Scatter plot for the separated inversion; e) ERT map obtained from the joint inversion; f) SRT map obtained from the joint inversion; g) Map of the cross-gradients function for the joint inversion; h) Scatter plot for the joint inversion.