GNGTS 2022 - Atti del 40° Convegno Nazionale

452 GNGTS 2022 Sessione 3.2 INTEGRATED ANALYSIS OF HVSR AND BOREHOLE DATA TO IMPROVE THE GEOLOGICAL MODEL OF THE SUBSOIL OF PALERMO TOWN (SICILY, ITALY) IN THE ORETO RIVER AREA. A. Canzoneri, R. Martorana, M. Agate, P. Capizzi University of Palermo, Department of Earth and Marine Sciences (DISTEM), Italy Introduction. In the present work the preliminary results are presented, related to the joint examination of boreholes and seismic data acquired in the area of the Palermo plain located near the bed of the Oreto River. This study was developed to define a more reliable model of the stratigraphic, geotechnical and geophysical features of the Palermo plain and to provide a more detailed definition of the depth of the bedrock and the thickness of the sedimentary cover. Geomorphological and geological setting: the Palermo plain and the Oreto River . The Palermo plain displays a maximum extension of about 6 km and an altitude between 0 m and 150 m. s.l.m. This area is located between the Tyrrenian Sea and the Meso-Cenozoic carbonate reliefs that develop their structure mainly along a N-S alignment, in the western sector, and along a NW-SE trend in the eastern corner of the plain. Meso-Cenozoic carbonate rocks and Cenozoic flyschoid deposits composing the mountains surrounding Palermo town have been intercepted and recognised by some boreholes at depths over a hundred meters beneath the Palermo plain. These older lithologies are up-covered by 1.5-0.8 Ma aged calcarenitic and sandy deposits. This stratigraphic setting is the results of the “Calabrian” marine transgression that affected the area starting from the Pleistocene. Quaternary marine sediments, forming a shallowing upward succession named as “Sintema di Marsala” (Agate et al. , 2017), deposited during this event. These rocks outcrop in a large area of the plain. In particular these rocks are composed by conglomerates, sands, blue clays (“Ficarazzi clays”; Ruggieri et al. , 1975) and variously cemented sandy and bioconstructed deposits of the “Palermo Calcarenites”. Above thesemarine rocks, thecoastal conglomerates and sands of “Sintemaof Buonfornello- Campofelice” (middle Pleistocene) and of the “Sintema of Barcarello” (upper Pleistocene may also outcrop. These latter, consist of conglomerates and variously cemented sandstones and colluvial deposits of coastal environment (Cappadonia et al. , 2020). The Holocene deposits along the coast and within the current hydrographic network complete the stratigraphic succession. Themain course of the Oreto River has a length of about 20 km. This develops approximately from the above describes zone of the change in orientation of the Palermo Mounts, up to its outflow located in the Gulf of Palermo. In the Palermo plain the riverpath is confined within a valley carved in the Oligo-Miocene deposits of the Numidian Flysch. In the stretch of the river flowing in the urban area, represented in Fig. 1, the river course takes on a meandering trend with recessed shapes and several meters high banks consisting of Pleistocene deposits. The final stretch of the watercourse, modified by the hydraulic structures realized in the early decades of the 1900, was originally characterized by a meandering morphology and anastomized in several free branch before its mouth (Agnesi, 2021). The geological setting of the study area defines two different groundwaters reservoirs: one superficial linked to the calcarenitic rocks and a deeper one connected to the presence of fractured Meso-Cenozoic carbonates (Cusimano et al. , 2004). The study area (Fig. 1) corresponds to the zone enclosed between the coastline at east and a western sector in which the town ring road intersects the river path. Northern and southern