Faults distribution and seismogenic potential in the Calabrian backarc domain, SE Tyrrhenian Sea

T he Western Calabrian margin (Italy) is the most active segment of the Apennine back-arc system,formed in response to the slow Africa – Eurasia convergence. The offshore area represents thetransitional region between the arc and the back-arc: it is affected by several fault systems, mostof them able to trigger highly destructive earthquakes. Indeed, the Calabria and its westernoffshore are characterized by the highest seismic moment release of the entire Apennines, alsoevidenced by historical seismicity catalogue, the most accurate over the world. During lastdecades, scientific community invested huge resources in assessment of seismic and tsunamihazards. Furthermore, during last years several local-scale works allowed of improving knowledgeof the faults geometry, magmatism, seismogenic and tsunamigenic potential along the westernoffshore region (Loreto et al., 2017; Brutto et al., 2016; De Ritis et al., 2019). Some active faults,belonging to NE-SW-trending normal fault systems accommodating the inner-arc collapse relatedto slab-decupling, are also responsible of the most destructive historical sequences, still to beadequately characterized. Using vintage SPARKER 30 Kj acquired in the seventies and recentmultichannel seismic profiles together with middle resolution morpho-bathymetric data weproduced a new tectonic map of the Calabria back-arc system. Further, we characterized somebefore-unknown faults and linked them with shallow structures, as ridges and slumps / slides. Thisarea seemingly less populated of faults compared to the peri-Tyrrhenian margin, where severalfaults belong to different systems, i.e. (i) the rifting system active that allowed the opening of theTyrrhenian Basin and (ii) the slab-decupling related normal faults system currently active. Thecomparison with historical and instrumental seismicity allowed us to highlight possible seismicgaps that, if considered, could strongly improve the map of seismogenic potential of theTyrrhenian back-arc system.