An active oblique-contractional belt at the transitionbetween the Southern Apennines and Calabrian Arc:The Amendolara Ridge, Ionian Sea, Italy

High-resolution, single-channel seismic and multibeam bathymetry data collected at theAmendolara Ridge, a key submarine area marking the junction between the Apennine collision belt andthe Calabrian subduction forearc, reveal active deformation in a supposedly stable crustal sector. New data,integrated with existing multichannel seismic profiles calibrated with oil-exploratory wells, show that middleto late Pleistocene sediments are deformed in growth folds above blind oblique-reverse faults that bound aregional pop-up. Data analysis indicates that ~10 to 20 km long banks that top the ~80 km long, NW-SEtrending ridge are structural culminations above en echelon fault segments. Numeric modeling of bathymetryand stratigraphic markers suggests that three 45° dipping upper crustal (2–10km) fault segments underlie theridge, with slip rates up to ~0.5mm/yr. Segments may be capable with M~ 6.1–6.3 earthquakes, although anunknown fraction of aseismic slip undoubtedly contributes to deformation. The fault array that bounds thesouthern flank of the ridge (Amendolara Fault System) parallels a belt of Mw<4.7 strike-slip and thrustearthquakes, which suggest current left-oblique reverse motion on the array. The eastern segment of the arrayshows apparent morphologic evidence of deformation and might be responsible for Mw ≤ 5.2 historic events.Late Pliocene-Quaternary growth of the oblique contractional belt is related to the combined effects of stallingof Adriatic slab retreat underneath the Apennines and subduction retreat of the Ionian slab underneathCalabria. Deformation localization was controlled by an inherited mechanical interface between the thickApulian (Adriatic) platform crust and the attenuated Ionian Basin crust.