GNGTS 2014 - Atti del 33° Convegno Nazionale

90% of the total thickness of the sedimentary record is related to seismic shaking and tsunami generation. We studied the record of major earthquakes (1908, 1693 and 1169) on abyssal sedimentation to define source areas and causative faults. Future analysis are planned for a better definition of the relative contribution of seismic shaking and tsunami wave processes that result in the deposition of these Ionian Sea seismo-turbidites. Introduction and geological setting. The CA (Fig. 1) is located above a 300 km wide subduction zone dipping toward NW, characterized by an active volcanic arc (the Aeolian Islands), a back-arc basin (Tyrrhenian Sea) and a well defined Wadati-Benioff zone (Wortel and Spakman, 2000), with earthquakes descending to nearly 500 km depth (Selvaggi and Chiarabba, 1995). The present day tectonic configuration of the subduction system was reached after 1-0.7 Ma, when the plate boundary system reorganized to accommodate the Africa-Eurasia convergence. After the locking of the Apennines and southern Sicily (Gela nappe), shortening remained active offshore Calabria (Doglioni et al. , 1999) and resumed along an active belt located in the southern Tyrrhenian region (Billi et al. , 2007); as a consequence, a diffuse transform zone formed in NE Sicily and in the NW Ionian region to accommodate the remaining active portion of the slab beneath Calabria. The re-organization of the plate boundary is marked by two main processes: 1) 1-1.7 Ma, onset of uplift in Calabria; 2) 0.5 Ma, tholeitic magmas started to erupt building up the Mt. Etna, located on top of the western edge of the Calabria subduction zone. The external part of the arc (Fig. 1) is represented by a subduction complex bordered by two major structural features, the Malta escarpment to the SW, and theApulia escarpment to the NE. The CA accretionary wedge developed due to the SE-NW Africa/Eurasia plate convergence, presently occurring at a very slow rate (5 mm a -1 or less), according to recent Global Positioning System (GPS) studies (Reilinger et al., 2006; Serpelloni et al. , 2007; D’Agostino et al. , 2008; Fig. 1 – Geodynamic setting of the study area. Slip vector in the African reference frame is indicated by a red arrow. In green GPS vectors in the Apulian fixed reference frame in which the motion of Calabria is parallel to the slip vector suggesting the existence of active crustal compression as a result of subduction of the Ionian lithosphere beneath the Calabrian Arc (D’Agostino et al. , 2008). The NW ward dipping subducting slab of the African plate is represented by the yellow isodepth lines in the Tyrrhenian Sea spacing from 100 to 450 km depth (Selvaggi and Chiarabba, 1995). Eu: Europe, Afr: Africa. 164 GNGTS 2014 S essione 1.2