GNGTS 2022 - Atti del 40° Convegno Nazionale

470 GNGTS 2022 Sessione 3.2 area perimeter with, in the centre, the foundation to be investigated and using an intergeophonic space is 1 m (yellow rectangle in Fig.1a). Overall, 12 shots along the area perimeter and 4 shots in the internal sector in order were made in order to increase the investigation detail (Fig.1b, c). • 3D resistivity tomography was carried out using a pole–dipole sequence because it provides better horizontal coverage, reaches a greater depth of investigation (if compared with Wenner, Wenner–Schlumberger and dipole–dipole arrays) and the outcomes are less sensitive to the telluric noise, with respect to the dipole–dipole device. The ERT3D acquisition is superimposed on the SRT3D survey, as shown in figure 1b. Fig. 1 - Scheme of 3D surveys acquisition; a) 2D refraction seismic acquisition (red line); b) 3D refraction seismic and 3D resistivity tomography scheme acquisition; c) acquisition phases. The SRT2D dataset processing was carried out using the Rayfract Software (Intelligent Resources Inc., Canada), which allows both the reconstruction of the refractor geometry and the creation of detailed subsurface velocity models, specially in case of deep structures. The SRT3D dataset processing was carried out using the DW TOMO3D (Geogiga Technology Corporation) software designed for the processing of 3D data relating to seismic surveys P waves. More specifically, DW TOMO3D uses a grid ray tracing and the regularized inversion approach to derive the 3D velocity structure directly from first arrival times in 3D seismic