GNGTS 2013 - Atti del 32° Convegno Nazionale

Pondrelli S., Salimbeni S., Perfetti P. and Danecek P.; 2012: Quick regional centroid moment tensor solutions for the Emilia 2012 (northern Italy) seismic sequence . Annals of Geophysics, 55 , pp. 615-621. Scholz C. H.; 1988: The mechanisms of seismic quiescences . Pure Appl. Geophys., 126 , pp. 701-718. Serpelloni E., Anderlini L., Avallone A., Cannelli V., Cavaliere A., Cheloni D., D’Ambrosio C., D’Anastasio E., Esposito A., Pietrantonio G., Pisani A., Anzidei M., Cecere G., D’Agostino N., Del Mese S., Devoti R., Galvani A., Massucci A., Melini D., Riguzzi F., Selvaggi G. and Sepe V.; 2012: GPS observations of coseismic deformation following the May 20 and 29, 2012, Emilia seismic events (northern Italy): data, analysis and preliminary models . Annals Of Geophysics, 55 , pp. 759-765. Activetectonicsofsouth-easternSicilyasdepictedbyseismological and geodetic observations C. Musumeci, M. Palano, D. Patanè, L. Scarfì Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo - Sezione di Catania, Italy Introduction. Southeastern Sicily, one of the most seismically hazardous zones in central Mediterranean area, experienced several historical destructive events such as the 1169 and 1693 earthquakes (MCS intensities of XI with estimated magnitudes of about 7 or higher; Boschi et al. , 2000), and more recently, a M L = 5.4 earthquake occurred on December 13, 1990 about 10 km offshore (Amato et al. , 1995). From a geological point of view, southeastern Sicily must be considered in the frame of the complex tectonic features of the Mediterranean basin, which is dominated by the ~N20°W Neogene-Quaternary convergence between Nubian plate (the African plate west of the East African Rift) and Eurasia, occurred in the last 100 million years (Faccenna et al. , 2001). It is mostly formed by the foreland domain (the Hyblean Plateau; Fig. 1a), a crustal unit located at the northeastern end of the mostly submerged Pelagian Block extending up to Sicily Channel, the Maltese islands and Tunisia ( e.g. Malinverno and Ryan, 1986; Boccaletti et al. , 1990; Patacca et al. , 1990). The Sicilian foreland consists of a thick Meso-Cenozoic sequence of carbonate sediments which are underlain by a continental basement of unknown age (Yellin-Dror et al. , 1997). Eastward, the foreland is bounded by the NNW-SSE-striking Hybleo-Maltese Escarpment Fault System (HMEFS; see Fig. 1a), a Mesozoic lithospheric boundary separating the Ionian oceanic basin from the thick Pelagian Block continental crust (Nicolich et al. , 2000). The northern and western margins of the Hyblean Plateau are characterized by an older extensional belt (named Gela-Catania Foredeep), that is downbent by a NE-SW fault system under the front of the northern imbricate mountain chain (Appennine-Maghrebian Chain or Maghrebian Thrust Belt; Yellin-Dror et al. , 1997). The frontal thrust belt was considered locked since the Middle Pleistocene (Butler et al. , 1992; Lickorish et al. , 1999; Tortorici et al. , 2001), but recent studies, based on geological (Bousquet and Lanzafame, 2004; Catalano et al. , 2008), seismolological (Lavecchia et al. , 2007; Visini et al. , 2009) and geodetic (see Palano et al. , 2012 for an overview) observations have detected the occurrence of active contraction. Another main tectonic alignment is a 70 km long fault system (named as Scicli line or Scicli- Ragusa Fault System, SRFS in Fig. 1b: Ghisetti and Vezzani, 1980, Grasso and Reuther, 1988) extending along the main direction striking about N-S and the conjugated structures NE-SW from northeast to southwest of the western district of the foreland. Despite the recent advances achieved through geological, seismological and geodetic studies (among others Scarfì et al. , 2007; Catalano et al. , 2008; Palano et al. , 2012), the geodynamic processes and the tectonic regime of southern Sicily are far from being unanimously described. Several aspects related to the geometry, type and contributions of each fault and its seismogenic role have still not been satisfactorily explored and there is little consensus regarding the location and geometry of the faults causing major earthquakes. In this work, exploiting local monitoring network high-quality data, we performed an in- depth analysis of the ongoing tectonics of southeastern Sicily, between the outermost front of 215 GNGTS 2013 S essione 1.2