A recent tectonic reorganization in the south-central Mediterranean

Abstract

New geodetic data combined with seismicity, geologic and geochemical information document a major tectonic reorganization in the central Mediterranean around 0.8–0.5 Ma, when rapid trench migration and consequent Tyrrhenian back-arc extension which dominated the region's evolution since the Tortonian (10–8 Ma) essentially stopped. In response, the African convergence in Sicily was transferred to a back-thrust in the Southern Tyrrhenian, characterized by frequent M5–6 earthquakes in the last 20 years. A diffuse transform boundary formed across northeastern Sicily to connect the Sicilian and Calabrian plate boundaries, causing opening of the Messina Straits—home to large historical earthquakes—and unusual volcanism in the Aeolian Island arc and the intraplate Mount Etna. A divergence of the Ionian region from the main part of Africa, with northeastward motions that reflect the joint influence of African push and Hellenic slab pull, and are transmitted to Calabria and Adria, could explain motions observed in the Sicily Channel, Calabria and Apulia, as well as the high level of southeastern Sicilian seismic activity.