GNGTS 2017 - 36° Convegno Nazionale

GNGTS 2017 S essione 1.2 165 High-resolution geophysical data, including detailed morpho-bathymetry, have been acquired in the Gulf of Taranto in the last decade and led to the identification of geomorphic features and related deposits recording important mass movement events (Ceramicola et al. , 2014). FASTMIT will acquire new seismic data in these locations in order to link the observed geomorphic features (i.e. slope failures, buried debris flows) with deeper structures responsible of their origin and representing potential seismic hazards. Both in the Gulf of Taranto and in the Salento offshore, many of the deep geological structures responsible for the seismicity in this area are still debated and further and more focused studies are necessary in order to improve their characterization and turn them into an effective input for geohazard assessments. Two main earthquakes are historically documented in the Salento offshore (the 20 October 1974 earthquake, MI 5.1, and the 20 February 1743 earthquake, Mw 7.1) whose origin has never been thoroughly explained and for which a potential tsunami threat for the Puglia coastline should thus be investigated. The seismic profiles acquired along the Apulia Platform show numerous crustal normal faults subparallel to the Calabrian accretionary wedge front. The major normal faults display slope breaks with great lateral continuity where gravity-driven processes are observed in the seafloor (Ceramicola et al. , 2014). Argnani et al. (2001) firstly recognized the presence of a system of horst and graben in the Salento offshore and interpreted it as a spatially limited features related to the flexural stress acting on the Apulia Platform. Recent seismic reflection profiles and a detailed morpho-bathymetric survey acquired by OGS (Volpi et al. , 2017) confirm the presence of a 50 km NW-SE elongated horst-and-graben system in the central part of the Apulia foreland, southeast of Leuca town. The same evidence was found in the multichannel profiles provided in the collaborative framework between INGV and Spectrum Geo (CA-60). The grabens are bounded by high-angle normal faults and are characterized by the presence of the syn-tectonic basins with evidence of growth strata in the Plio-Pleistocene succession. The resolution of the data and the absence of detailed stratigraphic constraints in the area do not allow to make precise considerations on the age of inception and rates of activity of the fault system. For this reason, it is of fundamental importance the study of this fault system in the Salento offshore and its eventual relationship with the historical seismicity of the Otranto channel. In this contribution, we present the preliminary results of the analysis carried out with the available data and the program of data acquisition (high-resolution multichannel seismic profiles and a core log) to better detail the geometry and kinematics of the Salento offshore fault system in the framework of the FASTMIT project. The results of this study will be used to update the seismogenic sources database DISS and EDSF (Basili et al. , 2013; Basili et al. , 2008) and to improve the seismic and tsunami hazard assessment in the northern Ionian Sea area. References Argnani, A., Frugoni, F., Cosi, R., Ligi, M. and Favali, P.; 2001: Tectonics and seismicity of the Apulian Ridge south of Salento peninsula (Southern Italy). Annals of Geophysics, 44(3). Basili, R., Kastelic, V., Demircioglu, M.B., Garcia Moreno, D., Nemser, E.S., Petricca, P., Sboras, S.P., Besana- Ostman, G.M., Cabral, J., Camelbeeck, T., Caputo, R., Danciu, L., Domac, H., Fonseca, J., Garc������������� ía-Mayordomo, J., Giardini, D., Glavatovic, B., Gulen, L., Ince, Y., Pavlides, S., Sesetyan, K., Tarabusi, G., Tiberti, M.M., Utkucu, M., Valensise, G., Vanneste, K., Vilanova, S. and Wössner, J.; 2013: The European Database of Seismogenic Faults (EDSF) compiled in the framework of the Project SHARE . DOI: 10.6092 /INGV.IT -SHARE-EDSF Basili, R., Valensise, G., Vannoli, P., Burrato, P., Fracassi, U., Mariano, S., Tiberti, M.M. and Boschi, E.; 2008: The Database of Individual Seismogenic Sources (DISS), version 3: summarizing 20 years of research on Italy��’s earthquake geology . Tectonophysics, 453: 20-43. DOI: 10.1016/j.tecto.2007.04.014 Ceramicola, S., Praeg, D., Coste, M., Forlin, E., Cova, A., Colizza, E. and Critelli, S.; 2014: Submarine Mass- Movements Along the Slopes of the Active Ionian Continental Margins and Their Consequences for Marine