GNGTS 2016 - Atti del 35° Convegno Nazionale

GNGTS 2016 S essione 1.1 117 Savelli, C. and Schreider, A.A.; 1991: The opening processes in the deep Tyrrhenian basins of Marsili and Vavilov, as deduced from magnetic and chronological evidence of their igneous crust. Tectonophysics 190, 119-131. ViDEPI; 2009: Progetto Visibilità Dati Esplorazione Petrolifera in Italia, © 2009–2010 Ministero dello Sviluppo Economico UNMIG, Società Geologica Italiana, Assomineraria. http://unmig.sviluppoeconomico.gov.it/videpi/ Vilardo, G., Ventura, G., Terranova, C., Matano, F. and Nardò S.; 2009: Ground deformation due to tectonic, hydrothermal, gravity, hydrogeological, and anthropic processes in the Campania Region (Southern Italy) from Permanent Scatterers Synthetic Aperture Radar Interferometry. Remote Sensing of Environment, 113, 197-212. What we know about the earthquakes located around the Gulf of Patti? M.S. Barbano, C. Pirrotta Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Università di Catania, Italy Introduction. An accurate revision of the 1739 Naso seismic sequence has been carried out with the main purpose of better defining seismic parameters of these earthquakes and understanding the seismogenic potential of north-eastern Sicily. In the area of the Gulf of Patti two composite seismogenic sources were defined (DISS Working Group, 2015): the Tindari Fault system and the south Tyrrhenian seismic source. The Tindari Fault is a near-vertical, NNW-trending, SW-dipping, right-lateral strike-slip fault, that possibly belongs to the strike- slip system that dissects and advances the Calabrian arc toward SE. The south Tyrrhenian seismic source is an E-W narrow contraction belt that runs from north of Ustica to the Aeolian Islands, about 50 km off the northern Sicilian coast (e.g. Billi et al. , 2006; Barreca et al. , 2014). This belt is thought to accommodate 4-5 mm/y of the Africa-Europe convergence. The maximum magnitude for these seismogenic sources is based on few earthquakes that damaged the northern coast of Sicily. Historical catalogues (Guidoboni et al. , 2007; Rovida et al. , 2016) report a scant moderate seismicity (4.5 < Mw < 5.5) all over the region (Fig. 1). The main damaging earthquakes affecting the coastal area are the 10 March 1786 (Mw 6.14), the 5 March 1823 (Mw 5.8) and the 15 April 1978 (Mw 6.03). Being magnitudes and epicentre locations based on macroseismic data, they can be mistakenly estimated, especially considering that these data are distributed along coastal areas. Therefore, an offshore location for some of these events cannot be ruled out and magnitudes could be underestimated (e.g. Azzaro et al. , 2004). In the past 30 years several events with M > 5 occurred offshore, including the Mw 5.9 Palermo earthquake of 2002 (e.g. Pondrelli et al. , 2006). We analysed the earthquakes located in the area (Barbano et al. , 2016) and show that most of the events are poorly defined and probably underestimated like the 1739 earthquake. Fig. 1 – Earthquakes located in the studied area in the period 1400- 2014, after CPTI15 (Rovida et al. , 2016).