GNGTS 2019 - Atti del 38° Convegno Nazionale

688 GNGTS 2019 S essione 3.2 Gebrande H. and Miller H.; 1985: Refraktionsseismik, in Angewandte Geowissenschaften II, Methoden der Angewandten Geophysik und mathematische Verfahren in Geowissenschaften. Enke Verlag 226-260. Philips O.F., Kanungo D.P., Chauhan P. and Kumar R.K; 2019: Landslide Investigation Using Electrical Resistivity Tomography: a non-invasive Technique. The 4th World Congress on Disaster Management (WCDM-2019). Rathod H., Debeck S., Gupta R., and Chow B.; 2019: Applicability of GPR and a rebar detector to obtain Rebar information of existing concrete structures . Case Studies in Construction Materials 11:e00240. DOI: 10.1016/j. cscm.2019.e00240. Sibula I., Pladoa J. and Jõelehta A.; 2017: Ground-penetrating radar and electrical resistivity tomography for mapping bedrock topography and fracture zones: a case study in Viru-Nigula, NE Estonia. Estonian Journal of Earth Sciences 66 (3), 142–151. Singer J.A., Link C.A. and Iverson S.R.; 2009: Mining Publication: High Resolution Seismic Refraction Tomography for Determining Depth of Blast Induced Damage in a Mine Wall. Journal of Explosives Engineering 27 (1). Tosti F., and Ferrante C.; 2019: Using Ground Penetrating Radar Methods to Investigate Reinforced Concrete Structures . Surveys in Geophysics, DOI: 10.1007/s10712-019-09565-5. Villani F., Pucci S., Civico R., De Martini P.M., Cinti F.R. and Pantosti D; 2018: Surface Faulting of the 30 October 2016 Mw 6.5 Central Italy Earthquake: Detailed Analysis of a Complex Coseismic Rupture . Tectonics, 37 (10), 3378-3410. Yusof1 M.A.H., Azman M.I.M.F., Ismail N.A. and Ismail N.E.H.; 2017: Applying 2-D resistivity imaging and ground penetrating radar (GPR) methods to identify infiltration of water in the ground surface. AIP Conference Proceedings, 1861, 1 , 030011. Liu S., Weng C., Jiao P.; 2013: GPR signal analysis of post-tensioned prestressed concrete girder defects . Journal of Geophysics and Engineering 10 (3). DOI: 10.1088/1742-2132/10/3/034005. 3D RESISTIVITY AND INDUCED POLARIZATION COMBINED TOMOGRAPHIES: AN OPTIMAL CONFIGURATION FOR DEMINING IN URBAN AREAS P. Luiso 1 , C. De Paola 1,2 , D. Di Massa 1 , D. Fiore 1 , F. Pagliara 1 1 SOCOTEC Italia Srl - registered office, Lainate, Italy 2 Dipartimento di Scienze della Terra, dell’Ambiente e delle Risorse, Università degli Studi «Federico II», Naples, Italy Introduction. The 3D resistivity tomography surveys (ERT 3D) is a technique that allows both to investigate the subsoil and the foundational structures (Oyeyemi et al. , 2017) and to reconstruct 3D volumes, through a three – dimensional representation of the resistivity values. The 3D resistivity tomography is used for several purposes such as: investigation of mineral deposits (e.g. Alile et al. , 2017), detection of buried fractures on urban areas (e.g. Chàvez et al. , 2014), identification of faults extension (Lecocq et al. , 2017; Petrit et al. , 2018). In the last ten years, the ERT surveys are widely used in urban investigations to the detection of urban services and/or the presence of landmines (Metwaly et al. , 2008). In general, geophysical measurements in urban environments can be very complicated to carry out due to the restrictions of available space and the high noise levels (Rossi et al. , 2018). However, an optimal spread configuration could give good results and accurate values of resistivity. In this paper, we present a detailed 3D survey carried out in Trento, north Italy, for the construction of a subway under the existing railway lines (currently in use). The aim was to identify the potential presence of World War II bombs and distinguish them from the urban services. To reduce the possible noise due to the rails, and providing in the best way the imaging of volumes that involves the portion of ground immediately below the railway lines, we introduced an innovative configuration to measure the resistivity and chargeability values: we located the measurement spreads along the railway lines, but at a lower altitude of the same (Fig. 1). In details, we correlated induced polarization (IP) data with high resolution 3D resistivity tomography carried out using a pole–dipole sequence. We preferred to use the 3D survey and