GNGTS 2017 - 36° Convegno Nazionale

108 GNGTS 2017 S essione 1.2 Structural pattern and active deformation in the northern sector of the Aeolian-Tindari-Letojanni fault system in the geodynamic framework of the southern Calabrian Arc: an integrated analysis of field, marine geophysical, seismological and geodetic data G. Barreca 1,7 , F. Cultrera 1 , L. Ferranti 2,7 , C. Monaco 1,7 , F. Pepe 3 , S. Passaro 4 , G. Barberi 5 , V. Bruno 5 , P. Burrato 6 , M. Mattia 5 , C. Musumeci 5 , L. Scarfì 5 1 Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Sezione di Scienze della Terra, Università di Catania, Italy 2 Dipartimento di Scienze della Terra, delle Risorse e dell’Ambiente, Università “Federico II”, Napoli, Italy 3 Dipartimento di Scienze della Terra e del Mare, Università di Palermo, Italy 4 Istituto per l’Ambiente Marino Costiero, C.N.R., Napoli, Italy 5 Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio etneo, Catania, Italy 6 Istituto Nazionale di Geofisica e Vulcanologia, Roma 1, Roma, Italy 7 CRUST - Centro Interuniversitario per l’Analisi Sismotettonica Tridimensionale con Applicazioni Territoriali, Italy Framed in the current geodynamics of the central Mediterranean, the Aeolian-Tindari- Letojanni fault system (ATLFS) represents a key tectonic feature controlling volcanism and seismicity of southern Tyrrhenian Sea and north-eastern Sicily (Fig. 1A). Although it is widely accepted that the ATLFS is part of a wider NW-SE oriented right-lateral wrench zone developed at the southern edge of the Calabrian Arc, several issues about its structural pattern, active deformation processes and related seismogenic faulting are still unsolved. These aspects are of crucial importance is assessing its seismogenic potential considering that, as provided by seismological, geodetic and geological data (Billi et al. , 2006; Palano et al. , 2012; Barreca et al. , 2014; Scarfì et al. , 2016), ATLFS is still active heaving produced about 2000 earthquakes with small-to-moderate magnitude (1.0 ≤Ml≤ 4.8) in the last 30 years. Moreover, the analysis of historical catalogues revealed that this area was also affected by several strong earthquakes in the past such as the Mw=6.2 event in March 1786 and the Mw=6.1 one in April 1978, which caused severe damages in the surrounding localities (Gasparini et al. , 1982; Rovida et al. , 2011). In order to investigate the structural architecture and the active deformation pattern of the northern sector of this deformation belt, structural observations on-land, high and very-high resolution seismic reflection profiles, swath bathymetry and seismological and geodetic data were merged from the Lipari-Vulcano volcanic complex to the Peloritani Mountains across the Gulf of Patti (Fig. 1B). As a whole, structural measurements were performed along the on-land sectors of the faults belt (i.e. Lipari-Vulcano complex and Tindari-Barcellona Depression, Fig. 1B) and highlight how the zone is mainly deformed by right-lateral transtensional faults along the NNW-SSE direction. Minor faults, cinematically linked to the previous, consist of NE-SW to NNE-SSW trending normal to oblique faults. In mainland Sicily, the main set is represented by a NW-SE to NNW-SSE trending right-oblique (transtensional) fault zone which extends for ~20 km from Capo Tindari to Novara village (Tindari-Novara fault zone, TNFZ). The offshore sector (i.e. between Vulcano Island and the Gulf of Patti) was investigated throughmarine geophysical survey during which high (sparker) and very-high (Chirp) resolution seismic reflection profiles and about 1100 km² of swath bathymetrywere acquired. The combined analysis of these data point out that oblique NW-SE striking faults are widespread all over the offshore sector often forming horst and graben structural associations and controlling the main morpho-bathymetric features (e.g. the Milazzo Canyon and the Patti Valley, Fig. 2A). Overall, offshore geophysical surveys allow detecting two major oblique structural lineaments oriented NW-SE, the Vulcano-Milazzo fault zone (VMFZ) and the Patti Valley fault zone (PVFZ). Further, chirp profiles revealed that some of the detected fault segments reach the seafloor producing up to 3 m-high scarps. By merging the results coming from the on-land and marine investigations on a new structural map, a more complete structural framework of the whole area was obtained (Fig. 2B). Major