[1] The Neogene tectonics of the central Mediterranean are related to the subduction and trench rollback of the Ionian basin under Eurasia, causing the opening of the Liguro-Provencal and Tyrrhenian back-arc basins and the formation of the Calabrian accretionary wedge. The Calabrian accretionary wedge is a partially submerged accretionary complex located in the Ionian offshore and laterally bounded by the Apulia and Malta escarpments. While the history of the back-arc extension process is fairly well defined, the structure and evolution of the wedge are still poorly known. We have analyzed and interpreted the available reflection multichannel and single-channel seismic profiles in the Ionian offshore and integrated them with other geological and geophysical data acquired in the last 40 years. Here we present unpublished seismic profiles to provide a new map of the tectonic structure of the Ionian offshore and to define the structure of the wedge and its evolution during the last 15 Myr. Our reconstruction points out that the Messinian salinity crisis represents an important break in the evolution of the wedge, as the basal décollement ramps up onto the Messinian salt deposits, producing a dramatic and fast forward propagation of the frontal thrust and resulting underplating of the underlying crustal Ionian sequence during progressive trench rollback. Our results provide new insight into the style of accretion in a weakly converging setting, which is typical for the Mediterranean region.

""Calabria represents an ideal site to analyze the. topography of a subduction zone as it is located on. top of a narrow active Wadati‐Benioff zone and shows. evidence of rapid uplift. We analyzed a pattern of surface. deformation using elevation data with different. filters and showed the existence of a long wavelength. (>100 km) relatively positive topographic signal at the. slab edges. The elevation of MIS 5.5 stage marine. terraces supports this pattern, although the record is. incomplete and partly masked by the variable denudation. rate. We performed structural analyses along. the major active or recently reactivated normal faults. showing that the extensional direction varies along the. Calabrian Arc and laterally switches from arc‐normal,. within the active portion of the slab, to arc‐oblique or. even arc‐parallel, along the northern and southern slab. edges. This surface deformation pattern was compared. with a recent high resolution P wave tomographic. model showing that the high seismic velocity anomaly. is continuous only within the active Wadati‐Benioff. zone, whereas the northern and southwestern sides are. marked by low velocity anomalies, suggesting that. large‐scale topographic bulges, volcanism, and uplift. could have been produced by mantle upwelling. We. present numerical simulations to visualize the threedimensional. mantle circulation around a narrow retreating. slab, ideally similar to the one presently subducting. beneath Calabria. We emphasize that mantle upwelling. and surface deformation are expected at the edges of. the slab, where return flows may eventually drive decompression. melting and the Mount Etna volcanism."

In the western Mediterranean area, after a long period (late Paleogene-Neogene) of Nubian (W-Africa) northward subduction beneath Eurasia, subduction has almost ceased, as well as convergence accommodation in the subduction zone. With the progression of Nubia-Eurasia convergence, a tectonic reorganization is therefore necessary to accommodate future contraction. Previously-published tectonic, seismological, geodetic, tomographic, and seismic reflection data (integrated by some new GPS velocity data) are reviewed to understand the reorganization of the convergent boundary in the western Mediterranean. Between northern Morocco, to the west, and northern Sicily, to the east, contractional deformation has shifted from the former subduction zone to the margins of the two back-arc oceanic basins (Algerian-Liguro-Provençal and Tyrrhenian basins) and it is now mainly active in the south-Tyrrhenian (northern Sicily), northern Liguro-Provençal, Algerian, and Alboran (partly) margins. Onset of compression and basin inversion has propagated in a scissor-like manner from the Alboran (c. 8 Ma) to the Tyrrhenian (younger than c. 2 Ma) basins following a similar propagation of the cessation of the subduction, i.e., older to the west and younger to the east. It follows that basin inversion is rather advanced on the Algerian margin, where a new southward subduction seems to be in its very infant stage, while it has still to really start in the Tyrrhenian margin, where contraction has resumed at the rear of the fold-thrust belt and may soon invert the Marsili oceanic basin. Part of the contractional deformation may have shifted toward the north in the Liguro-Provençal basin possibly because of its weak rheological properties compared with those of the area between Tunisia and Sardinia, where no oceanic crust occurs and seismic deformation is absent or limited. The tectonic reorganization of the Nubia-Eurasia boundary in the study area is still strongly controlled by the inherited tectonic fabric and rheological attributes, which are strongly heterogeneous along the boundary. These features prevent, at present, the development of long and continuous thrust faults. In an extreme and approximate synthesis, the evolution of the western Mediterranean is inferred to follow a Wilson Cycle (at a small scale) with the following main steps : (1) northward Nubian subduction with Mediterranean back-arc extension (since ~35 Ma); (2) progressive cessation, from west to east, of Nubian main subduction (since ~15 Ma); (3) progressive onset of compression, from west to east, in the former back-arc domain and consequent basin inversion (since ~8–10 Ma); (4) possible future subduction of former back-arc basins.

.[1] It is well known that the Ionian Sea is characterized by thin (8-11 km) crystalline crust, thick (5-7 km) sedimentary cover, and low heat flow, typical for a Mesozoic (at least) basin. Yet seismic data have not yielded univocal interpretations, and a debate has developed on the oceanic versus "thinned continental" nature of the Ionian basin. Here we analyze the magnetic anomaly pattern of the Ionian Sea and compare it to synthetic fields produced by a geopotential field generator, considering realistic crust geometry. The Ionian basin is mostly characterized by slightly negative magnetic residuals and by a prominent positive (150 nT at sea level) "B" anomaly at the northwestern basin margin. We first test continental crust models, considering a homogeneous crystalline crust with K = 1 Â 10 À3, then a 5 km thick deep crustal layer of serpentinite (K = 1 Â 10 À1). The first model yields insignificant anomalies, while the second gives an anomaly pattern anticorrelated with the observed residuals. We subsequently test oceanic crust models, considering a 2 km thick 2A basaltic layer with K = 5 Â 10 À3 , magnetic remanence of 5 A/m, and a unique magnetic polarity (no typical oceanic magnetic anomaly stripes are apparent in the observed data set). Magnetic remanence directions were derived from Pangean-African paleopoles in the 290-190 Ma age window. Only reverse polarity models reproduce the B anomaly, and among them the 220-230 Ma models best approximate magnetic features observed on the abyssal plain and at the western basin boundary. The Ionian Sea turns out to be the oldest preserved oceanic floor known so far.

A century after the catastrophic event, the sources of the 1908 Messina, Southern Italy, earthquake and tsunami, which caused at least 60,000 deaths, remain uncertain. Through a simple backward ray‐tracing method, we convert the tsunami travel‐time data reported in a 100‐years‐old paper into distances and find that the sources of the earthquake and tsunami are different. Overturning a long‐held assumption, reconsideration of the available tsunami, bathymetric, seismic, and seismological data indicates that the tsunami was generated by an underwater landslide.