Morphotectonics of the Gulf of Patti (Southern Tyrrhenian Sea) through pseudo-3D geophysical techniques

Abstract The Aeolian-Tindari-Letojanni Fault System (ATLFS) is a major tectonic transfer zone extending from the Sicilian coast to the Aeolian Islands through the Gulf of Patti. It is characterized by intense seismicity, including moderate to strong historical earthquakes. The ATLFS is considered the shallow expression of the Subduction-Transform Edge Propagator (STEP) fault, which marks the southwestern termination of the Calabrian slab. Recent studies interpret the neotectonic features in the Gulf as resulting from a dextral stepover between ATLFS segments, but the geometry and activity of major faults within this depression remain uncertain. To clarify these aspects, we built a pseudo-3D tectonic model from a dense grid of seismic reflection profiles integrated with morpho-bathymetric and seismological data. Our results reveal a broad deformation zone controlling a composite sedimentary basin, where pull-apart depressions are formed by overstepping transtensional faults that cut across the Calabrian Arc causing localized subsidence superimposed on regional uplift. This configuration supports the presence, at deeper crustal and mantle levels, of a lithospheric structure acting as a STEP fault developed after the necking of the Calabrian slab.