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The deep seismicity and lateral distribution of seismic velocity in the Central Western Mediterranean, point to the existence under the Alboran and Tyrrhenian Seas of two lithospheric slabs reaching the mantle transition zone. Gibraltar and Calabrian narrow arcs correspond to the slabs. Similarities in the tectonic and mantle structure of the two areas have been explained by a common subduction and roll-back mechanism, in which the two arcs are symmetrical end members. We present a new 3-D tomographic model at mantle scale for the Calabrian Arc and compare it with a recently published model for the Gibraltar Arc by Monna et al. ( 2013a ). The two models, calculated with inversion of teleseismic phase arrivals, have a scale and parametrization that allow for a direct comparison. The inclusion in both inversions of ocean bottom seismometer broadband data improves the resolution of the areas underlying the seafloor networks. This additional information is used to resolve the deep structure and constrain the reconstruction of the Central Western Mediterranean geodynamic evolution. The Gibraltar tomography model suggests that the slab is separated from the Atlantic oceanic domain by a portion of African continental margin, whereas the Calabrian model displays a continuous oceanic slab that is connected, via a narrow passage (~ 350 km), to the Ionian basin oceanic domain. Starting from the comparison of the two models we propose the following interpretation: within the Mediterranean geodynamic regime (dominated by slab rollback) the geometry of the African continental margin, located on the lower plate, represents a critical control on the evolution of subduction. As buoyant continental lithosphere entered the subduction zones, slab pull caused tears in the subducted lithosphere. This tectonic response, which occurred in the final stages of arc evolution and was strongly controlled by the paleogeography of the subducted plates, explains the observed differences between the Gibraltar and Calabrian Arcs.

The Straits of Messina and its surroundings are considered as one of the most tectonically active area of the Mediterranean. but in spite of their hazard potential. modern geophysical data aimed at investigating their hidden structures are lacking In order to bridge this gap, we carried out a marine multichannel seismic survey primarily aimed at: i) studying the regional fault pattern in the area of the Messina 1908 earthquake, and ii) checking the existence of a potentially seismogenic fault, the Taormina Fault, Which many authors locate offshore, along the coast between Taormina and Messina. Our seismic :)profiles show a great structural complexity within the Messina Straits. with the best imaged faults occurring on the Calabrian side In particular, a more than 30 km long NW-trending fault located at the SW tip of Calabria is cutting the sea floor Moreover, our data did not image any extensional fault plane attributable to the Taormina Fault: rather, the whole slope has been tilted east-ward The geodynamic Implication is that extension in south-eastern Sicily, on the Ionian side of the Hyblean Plateau, and extension in southern Calabria and Messina Straits belong to two different tectonic systems and cannot be mechanically linked.

The study area is located in the south-eastern part of the Crati valley (Northern Calabria, Italy), which is a graben bordered by N-S trending normal faults and crossed by NW-SE normal left-lateral faults. Numerous severe crustal earthquakes have affected the area in historical time. Present-day seismic activity is mainly related to the N-S faults located along the eastern border of the graben. In this area, much seismically induced deep-seated deformation has also been recognised. In the present paper, radon concentrations in soil gas have been measured and compared with (a) lithology, (b) Quaternary faults, (c) historical and instrumental seismicity, and (d) deep-seated deformation. The results highlight the following: (a) There is no evidence of a strong correlation between lithology and the radon anomalies. (b) A clear correlation between the N-S geometry of radon anomalies and the orientation of main fault systems has been recognised, except in the southernmost part of the area, where the radon concentrations are strongly affected by the superposition of the N-S and the NW-SE fault systems. (c) Epicentral zones of instrumental and historical earthquakes correspond to the highest values of radon concentrations, probably indicating recent activated fault segments. In particular, high radon values occur in the zones struck by earthquakes in 1835, 1854, and 1870. (d) Deep-seated gravitational deformation generally coincides with zones characterised by low radon concentrations.