GNGTS 2019 - Atti del 38° Convegno Nazionale

156 GNGTS 2019 S essione 1.2 Results and conclusions. Seismic and geodetic moment-rates estimation highlights that over the investigated area, only a small fraction of the measured deformation is released seismically, clearly indicating an apparent seismic moment deficit. Such a deficit would suggest either a proportion of aseismic deformation (i.e., ongoing unloading by creep and other plastic process) or accumulating strain not released by seismicity (i.e. elastic storage). The integrated analysis of available morpho-bathymetric data and seismic reflection profiles allows to identify main tectonic features whose location, geometry and inferred kinematics is in good agreement with observed recent seismicity and geodetic data. Basin depocenters mark first order structural boundaries between different morphostructural domains. However, seismic reflection data suggest that these structural depressions are not tectonically active, since recent sediment filling the basin depocenter does not show evidence of incipient deformations, while horizontally onlapping the acoustic basement. The infill of the basins could be subdivided into two different seismo-stratigraphic units, the lower showing evidence of past deformations. Consequently, the unconformity separating the lower, deformed, and the upper undeformed units, although not precisely stratigraphically correlated, represents the end of tectonic activity responsible for the opening of the deep depressions. Seismic reflection profiles show evidences of active deformation along a N-S trending corridor, where a diffuse and complex pattern of transtensional and transpressional deformation is presently affecting the sedimentary sequence up to the seafloor. These evidences suggest that fully seismic deformation occurs mainly along very narrow active tectonic areas which are unable to account for the total deformation budget measured geodetically. References Amato A. and Mele F.; 2008: Performance of the INGV National Seismic Network from 1997 to 2007 . Annals of Geophysics, 51, 417-431, DOI 10.4401/ag-4454. Argnani A.; 1990: The Strait of Sicily rift zone: foreland deformation related to the evolution of a back-arc basin . Journal of Geodynamics, 12(2-4), 311-331, DOI 10.1016/0264-3707(90)90028-S. Ben-AvrahamZ. and GrassoM.; 1991: Crustal structure variations and transcurrent faulting at the eastern and western margins of the eastern Mediterranean . Tectonophysics , 196 (3-4), 269-277, DOI 10.1016/0040-1951(91)90326-N. Burollet P. F., Mugniot J. M. and Sweeney P.; 1978: The Geology of the Pelagian Block: The margins and basins off southern Tunisia and Tripolitania . In: Nairn A. E. M., Kanes W. H., Stehli F. G. (eds): The ocean basins and margins , pp. 331-359. Springer, Boston, MA. DOI 10.1007/978-1-4684-3039-4_6. Calò M., Parisi L. and Luzio D.; 2013: Lithospheric P- and S-wave velocity models of the Sicilian area using WAM tomography: procedure and assessments . Geophysical Journal International, Volume 195, Issue 1, 625–649, DOI 10.1093/gji/ggt252. Cavallaro D., Monaco C., Polonia A., Sulli A. and Di Stefano A.; 2016: Evidence of positive tectonic inversion in the north-central sector of the Sicily Channel . Natural Hazards, DOI 10.1007/s11069-016-2515-6. Chiarabba C. and Palano M.; 2017: Progressive migration of slab break-off along the southern Tyrrhenian plate boundary: Constraints for the present day kinematics . Journal of Geodynamics, 105 , 51-61, DOI 10.1016/j. jog.2017.01.006. Gasperini L. and Stanghellini G.; 2009: SeisPrho: An interactive computer program for processing and interpretation of high - resolution seismic reflection profiles . Comput. Geosci., 35 , 1497–1507, DOI 10.1016/j.cageo.2008.04.014. Grasso M., Behncke B., Di Geronimo I., Giuffrida S., La Manna F., Maniscalco R., Pedley H. M., Raffi S., Schmincke H. U., Strano D. and Sturiale G.; 2004: Carta geologica del bordo nord-occidentale dell’Avampaese Ibleo e del fronte della Falda di Gela . S.EL.C.A., Firenze. Herring T. A., King R. W., Floyd M. A. and McClusky S. C.; 2018: Introduction to GAMIT/GLOBK, Release 10.7 . Cambridge, Massachusetts Institute of Technology. Hyndman R. D. and Weichert D. H.; 1983: Seismicity and rates of relative plate motion on the plate boundaries of western North America . Geophys. J. R. Astron. Soc., 72, 59–82, DOI 10.1111/j.1365-246X.1983.tb02804.x. Kijko A. and Graham G.; 1998: Parametric-historic procedure for probabilistic seismic hazard analysis Part I: estimation of maximum regional magnitude mmax . Pure and Applied Geophysics, 152(3), 413-442, DOI 10.1007/ s000240050161. KijkoA. and Singh M.; 2011: Statistical tools for maximum possible earthquake magnitude estimation . Acta Geophys., 59, 674-700, DOI 10.2478/s11600-011-0012-6. Lodolo E., Civile D., Zecchin M., Zampa L. S. and Accainio F.; 2019: A series of volcanic edi ces discovered a few kilometers off the coast of SW Sicily . Marine Geology, 416, DOI 10.1016/j.margeo.2019.105999.