# Multi-Parametric Imaging of Etruscan Chamber Toms:
## 3 Results  
### Electrical Resistivity Results  
Figure 4 shows the resistivity profiles obtained from the inversion of the CCR measurements. The CCR2 profile (b-b' in Figure 4a) was recorded by crossing the excavated burial site Eb1 (Figure 3) to obtain a resistivity reference signature of the investigated targets. This burial was located on the border of the area, which was very close to a metallic fence that prevented the center of the capacitive dipoles from being towed over it.  
Figure 4: CCR resistivity sections. CCR inversion results of (**a**) profile a-a’, RMS 5.9% after six iterations (CCR1 in Figure 3); (**b**) profile b-b’, root mean square (rms) 5.4% after five iterations (CCR2 in Figure 3), and (**c**) profile c-c’, RMS 3.8% after five iterations (CCR3 in Figure 3). The solid black lines indicate the interpreted interface between units A and B. The topographies of the profiles were extracted via a high-resolution digital surface model (DSM). Recovered CCR anomalies are labeled with letters from e1 to e8.  
Nevertheless, the void presence was still well recognizable in the eastern margin of the profile where high resistivity values (\(\rho>2500\) Ohm.m) occur. Because of its marginal position, the Eb1 burial could not be correctly reconstructed by the inversion algorithm. Observing the distribution of resistivity values along the b-b' transect, it was possible to separate the data into two sub-horizontal electrical units. A shallower unit, \"A\", is characterized by \(\rho\) ranging between 500 and 900 Ohm.m and a thickness of approximately 4 m. This unit overlays a relatively lower resistivity unit, \"B\", where resistivity values are lower than 350 Ohm.m. Within unit A, three shallow high-resistive anomalous spots occur, characterized by \(\rho\) values higher than 1200 Ohm.m (e5, e6, and e7 in Figure 4). These resistivity anomalies appear to be regularly spaced in the order of approximately 8 m and lie at a depth of approximately 1.5 m below ground level.  
The CCR1 profile (a-a' in Figure 4b) shows a similar subsurface resistivity setting, permitting the identification of the same two units, A and B, and shows three additional high-resistive anomalous structures.  
In comparison with the CCR2 anomalies, these are slightly different in shape, spacing (approximately 10 m), depth, and output resistivity values (e1, e2, and e3 in Figure 4b).  
The profile CCR3 (c-c' Figure 4c) was recorded at a lower elevation on the paved road and it revealed completely different characteristics. According to the observed lower resistivity values, the resistivity color scale was centered on the unit B reference value (\(\rho\simeq 350\) Ohm.m). This new scale highlights a low resistivity anomaly (e8 in Figure 4c) that coincides with the entrance of an additional excavated tomb (Eb2 in Figure 3). This anomaly is characterized by \(\rho\) values lower than 150 Ohm.m and shows sharp vertical contrasts that interrupt the imaged resistivity homogeneity of unit B.  
To cross-check the recovered CCR resistivity anomalies, a high-resolution dipole-dipole array ERT survey (1 m electrode spacing) was conducted along the CCR2 profile (Figure 5). The ERT model confirmed the presence of the four resistivity anomalies whose positions are coincident with those recovered in the CCR2 profile. In addition, the model revealed the presence of a relatively thin (1 m) uppermost low-resistive layer (\(\rho<200\) Ohm.m) throughout the section, which is not as clearly identified.  
With the ERT profile, we were also able to clearly identify the excavated burial (Eb1, Figure 3). The electrical image of Eb1 appears as a rectangular-shaped anomaly (approximately 2 m high and 4 m wide). characterized by high resistivity values (\(\rho>2500\) Ohm.m).