## 3 Results  
### Inverse Models from the Simulated Data  
The inverse models obtained from the simulated data are shown in Figure 7, for each of the nine combinations between electrode areal arrangement and array configuration. In the volume rendering of the electrical resistivity distribution, isosurfaces of 30 \(\Omega\)m and 70 \(\Omega\)m highlight, respectively, the conductive anomalous zones and the resistive ones. The choice of these values, identical for all the inversions, was made after a careful analysis of the anomalous shapes. The shapes and sizes of the original prisms are represented by red and blue polygons in order to enhance the degree of correspondence between the anomalies resulting from the inversions and the prisms of the original model. As a quantitative indicator of the effectiveness of the inversions, we calculated the percentage of the volume enclosed by the anomalies with respect to the volume of the conductive or resistive prisms. The results are shown in Table 2.  
The inverse models relating to the electrode areal arrangement \(A\), in which the electrodes are equally spaced along the perimeter of a square, do not give satisfactory results, as none of them manages to identify the two resistive blocks. Only the \(\alpha\) and \(\gamma\) arrays somehow show conductive anomalies located below the center of the area, but with resistivity values always higher than 30 \(\Omega\)m and therefore very far from the real value. The electrode areal arrangement \(B\), having the electrodes equally spaced on the perimeters of two concentric squares, undoubtedly gives better results. For this arrangement, of the three array \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{\begin{tabular}{c} **Electrode** \\ **Areal Arrangement** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Electrode** \\ **Array Configuration** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Volume of** \\ **Resistive** \\ **Anomalies** \\ **(m\({}^{3}\))** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **\% of Volume** \\ **of the** \\ **Resistive** \\ **Prisms** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Volume of** \\ **Conductive** \\ **Anomalies** \\ **(m\({}^{3}\))** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **\% of Volume** \\ **of the** \\ **Anomalies** \\ **Prisms** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Volume of** \\ **of the** \\ **Anomalies** \\ **(m\({}^{3}\))** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **\% of Volume** \\ **of the** \\ **Anomalies** \\ **Prisms** \\ \end{tabular} } \\ \hline \multirow{3}{*}{\(A\)} & \(\alpha\) & 0 & 0 & 0 & 0 \\  & \(\beta\) & 0 & 0 & 0 \\  & \(\gamma\) & 0 & 0 & 0 \\ \hline \multirow{3}{*}{\(B\)} & \(\alpha\) & 11,940 & 37 & 4041 & 51 \\  & \(\beta\) & 76,581 & 239 & 9536 & 119 \\  & \(\gamma\) & 57,684 & 180 & 10,933 & 137 \\ \hline \multirow{3}{*}{\(C\)} & \(\alpha\) & 20,920 & 65 & 6161 & 77 \\  & \(\beta\) & 26,809 & 84 & 8916 & 111 \\ \cline{1-1}  & \(\gamma\) & 43,492 & 136 & 10,125 & 127 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: For each of the nine combinations of electrode areal arrangement and array configuration, the volume of resistive and conductive anomalies and their percentage with respect to the original volume of the prisms are shown. configurations tested, the \(\gamma\) array is the one that outlines the three blocks of anomalous resistivity with greater resolution and detail. In fact, the anomalies show lengths very close to the true ones and their volumes are quite close to the real ones, with a not excessive overestimation. Finally, the electrode areal arrangement \(C\), with four contiguous squares, provides satisfactory results even if qualitatively inferior to those of \(B\). In fact, in the latter models, the lengths of the resistive block are strongly underestimated, probably due to insufficient resolving power in the marginal zones of the investigated area.