The new earthquake locations and focal mechanisms catalogues for the western Ionian Sea, Italy

Abstract The Ionian Sea hosts the last remnant of Tethyan oceanic lithosphere subducting beneath Calabria, where active deformation generates significant seismicity, including earthquakes exceeding magnitude 7. The main tectonic structures - the Ionian Fault system, the Alfeo–Etna Fault system, and the Malta Escarpment - accommodate African–Eurasian plate convergence and margin segmentation under a transtensional regime. Here we present two new datasets of 3D earthquake locations and focal mechanism solutions to constrain fault kinematics in the Ionian region. The first dataset includes 5,240 relocated small-magnitude earthquakes (0.7 ≤ M L ≤ 4.7) recorded between 1990 and 2019. Hypocentral locations were determined integrating travel-times data from land-based and seafloor seismic stations to improve spatial resolution. The second dataset comprises 421 new focal mechanism solutions (1.5 ≤ M L ≤ 4.7) for earthquakes occurring in the Ionian Sea and adjacent areas.