GNGTS 2017 - 36° Convegno Nazionale

628 GNGTS 2017 S essione 3.2 R. Persico, Introduction to Ground Penetrating Radar: Inverse Scattering and data processing. Wiley, 2014, ISBN 9781118305003. S. Santos-Assuncao, V. Perez Gracia, O. Caselles, J. Clapes, V. Salinas, Assessment of complex masonry structures with GPR compared with other non/destructive testing studies, Remote Sensing, vol. 6. n. 9, pp. 8220-8247, 2014. Integrated geophysical surveys for the characterization of S. Michele Church subsoil (Acireale, eastern Sicily) S. Grassi 1 , G. Patti 2 , S. Imposa 1 , D. Boso 2 , G. Lombardo 1 , F. Panzera 1 1 Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Sezione di Scienze della Terra, Università di Catania, Italy 2 Geoexpert, Acireale, Catania, Italy Introduction. The S. Michele Arcangelo church is located in the downtown of Acireale (Fig. 1). It underwent, from time by time, to significant structural and architectonic changes. It was firstly erected in the 6th century and expanded in 1678 afterwards, it was heavily damaged during the 1693 earthquake, which ruined a large area of Eastern Sicily, and then it was re-built (1740 - 1790) and further enlarged in 1911 (Costarelli, 2005). The church is formed by a big aisle, having an elliptical shape with a longitudinal axes E-W oriented and it is covered by an ellipsoidal dome. In its west side, both the presbytery and the main altar are located. Outside the church, the vestibule and the pronaos, designed by Stefano Ittar according to the Neoclassic style, are sited (Fig.1b). The great dome, which cover the central aisle, was destroyed during the eastern Sicily 1818 earthquake (Imposa and Lombardo, 1985). In the present study, the outcomes of several non-invasive geophysical surveys are shown. Two seismic refraction prospections, processed through tomographic approaches, and electromagnetic investigations (Ground Penetrating Radar, GPR), were performed. The surveys aimed at finding the presence, in the church subsoil, of old wall remains and crypts ascribable to its early structure (Vafidis, 2003; Barilaro et al. , 2007; Forte and Pipan, 2008; Imposa and Mele, 2011; Imposa and Grassi, 2015). Geology. The geologic and structural setting of Acireale area is tightly linked to the volcano- tectonic evolution of Mt. Etna. Acireale is located on a plateau delimited towards East by a fault system known in the literature as the “Timpe di Acireale”. Along the fault escarpment, it is possible to observe the stratigraphic sequence that characterized the study area. It is indeed possible to distinguish eruptive products belonging to the Timpe Synthem, Acireale Synthem and Concazze Synthem (Upper Pleistocene) as well as Pleistocenic-Holocenic age volcanic products, belonging to the Piano Synthem (ISPRA, Fig. 1 - a) Location of Acireale municipality; b) photo of the San Michele Arcangelo Church; c) geological map of the study area (ISPRA, 2009).