GNGTS 2019 - Atti del 38° Convegno Nazionale

GNGTS 2019 S essione 1.2 155 the GPS velocities (referred to a fixed Eurasian reference frame), we computed the geodetic horizontal strain-rate tensor on a regular 0.25° x 0.25° grid by adopting the strategy described in Palano (2015). Estimated strain-rates highlight that the western sector is dominated by a prevailing contractional field with the minimum deformation axes having a W-E attitude in area comprises between Pantelleria and SW Sicily, and a WNW-ESE attitude in area comprises between Pantelleria and Lampedusa. The eastern sector is dominated by a prevailing extensional field with the maximum deformation axes aligned to the NE-SW direction, coupled with a minor contraction with the minimum deformation axes having a NW-SE attitude. For the area defined by the blue polygon in Fig. 1, we calculated the seismic moment-rate according to the Savage and Simpson (1997) formulation, assuming values of 3.3·10 10 N/m 2 and 20 km for rocks shear modulus and seismogenic thickness, respectively. Estimated geodetic moment-rate is 8.95·10 17 Nm/yr. Geophysical data. Several papers have provided details on main tectonic structures cutting the investigated area (e.g. Argnani, 1990; Lodolo et al. , 2019; Cavallaro et al. , 2017). All these data and their interpretations depict a complex geodynamic setting, where recent volcanism, rifting zones and compressive structures coexist. In this study the different morpho-tectonic domains proposed in previous studies have been analyzed through interpretation of a set of SPARKER seismic data acquired by IGM (now ISMAR-Bo) in the Sicily Channel during the 70’s (Fig. 2). These data, available only in hard copies, have been digitized, processed and geo-referenced using the open-source software Seisprho (Gasperini and Stanghellini, 2009). The source was a 30 kJ Teledyne system and the receiver was a single channel streamer with an active section of 50 m. Shot interval was 4-8 sec, corresponding to an horizontal spacing of about 12-24 m. Interpretation of these data allowed to identify first order morpho-tectonic domains and their structural boundaries. Structural and seismo-stratigraphic reconstructions aimed at identifying active tectonic features, their geometries and kinematics. Fig. 2 - Sparker seismic reflection line Y across the structural depression in the central Sicily Channel. Location of seismic profile in the inset map. Top: sparker seismic line with main faults indicated in red. Bottom: two close ups across the structural depression and transtensional faults to the South.