GNGTS 2019 - Atti del 38° Convegno Nazionale

GNGTS 2019 S essione 1.2 153 Pavano F., Catalano S., Romagnoli G. and Tortorici G.; 2018: Hypsometry and relief analysis of the southern termination of the Calabrian arc, NE-Sicily (southern Italy) . In: Geomorphology, 304, 74–88. doi:10.1016/j. geomorph.2017.12.029. A. Polonia, L. Torelli, A. Artoni, M. Carlini, C. Faccenna, L. Ferranti, L. Gasperini, R. Govers, D. Klaeschen, C. Monaco, G. Neri, N. Nijholt, B. Orecchio, R. Wortel; 2016: The Ionian and Alfeo–Etna fault zones: New segments of an evolving plate boundary in the central Mediterranean Sea? Tectonophysics 675 69-90. http://dx.doi . org/10.1016/j.tecto.2016.03.016 A. Polonia, L. Torelli, L. Gasperini, P. Mussoni; 2012: Active faults and historical earthquakes in the Messina Straits area (Ionian Sea) . Nat. Hazards Earth Syst. Sci. 12, 2311–2328. http://dx.doi.org/10.5194/nhess-12-2311-2012. Willet S.D., Hovius N., Brandon M.T. and Fisher D.; 2006 eds.: Tectonics, climate, and landscape evolution . In: Geological Society of America Special Paper, 398, 449 p., doi:10.1130/2006.2398(00). SEISMIC AND ASEISMIC CRUSTAL DEFORMATION ON SICILY CHANNEL (ITALY) F. Sparacino 1 , M. Palano 1 , A. Ursino 1 , S. Spampinato 1 , A. Polonia 2 , L. Gasperini 2 1 Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania, Osservatorio Etneo, Catania, Italy 2 ISMAR/CNR - Istituto di Scienze Marine - Consiglio Nazionale delle Ricerche, Bologna, Italy Introduction. Seismic and geodetic moment-rate comparisons can reveal regions with unexpected potential seismic hazard. Sicily Channel represents a region with a potentially moderate seismic hazard, due to the occurrence, in the recent past, of volcanic eruptions sometimes accompanied by significant seismic swarms (maximum magnitude value ≤ 5.0). By using both historical and instrumental seismic catalogs as well as an update geodetic velocity field we performed such a comparison for the Sicily Channel area. Achieved results are framed into the current tectonic framework of the study area as resulting from an integrated analyses of available morpho-bathymetric data and seismic reflection profiles collected in the last decades. Background setting. The Sicily Channel is part of the Pelagian block (Burollet et al. , 1978; Ben-Avraham and Grasso, 1991), a continental crustal portion of the African continental margin which extends from Tunisia to eastern Sicily and is separated from the Ionian Basin by Hyblean-Maltese Escarpment Fault System. The autochthonous sedimentary wedge (ca. 7-8 km thick) consists of Triassic to Pleistocene carbonate succession with intercalated dominantly submarine volcano-clastic units and minor lava flows (Grasso et al. , 2004). The evolution of the Pelagian block has been strongly influenced by the complex interaction between the Nubia and Eurasian plates. Since late Miocene, and mostly during the Pliocene, the Sicily Channel has been affected by extensional tectonic processes which leaded to the development of tectonic depressions (e.g. Pantelleria, Linosa and Malta troughs; Fig. 1). These depressions have been interpreted as large and discrete pull-apart basins involving deep crustal levels that developed in front of the Africa-Eurasia collisional belt within a large dextral wrench zone. Seismological data. To investigate the seismic characteristics of the Sicily Channel, we considered the instrumental seismicity using earthquake data recorded during the period 1983- 2018 by the INGV permanent seismic network (http://iside.rm.ingv.it) . We focused our attention on a NW-SE oriented sector with approximate coordinates of vertices: Lat. 37.00 - Long. 10.00, Lat. 38.60 - Long. 11.55, Lat. 35.68 - Long. 16.60, Lat. 33.73 - Long. 14.91 (Fig. 1). In this region we selected 1560 earthquakes, with magnitude up to 4.7. In order to estimate the magnitude of completeness Mc of the compiled catalogue for the investigated area, and the a and b values of the Gutenberg-Richter law, we analyzed the earthquake frequency-magnitude distribution. a, b and Mc values were estimated by using a maximum likelihood estimation technique (Wiemer,