Three-dimensional modelling of the Calabrian Subduction interface

Abstract

The Calabrian Arc is a one-of-a-kind subduction zone. It features one of the shortest subduction segment (<150 km), one of the thickest accretionary wedge, and the oldest subducted (280 Myr) oceanic crust of the World. Despite a convergence rate of 1-5 mm/yr and significant in-slab seismicity below 40 km depth, its shallow interface shows no sign of seismic activity. Nonetheless, it has occasionally be blamed to have generated some past large earthquakes and tsunamis. For all these reasons, the Calabrian Arc is a cornerstone in the Mediterranean plate-tectonics puzzle and the understanding of its geometry and behavior may strongly contribute to estimating the seismic and tsunami hazard in the region. This work presents a 3D reconstruction of the shallow portion (<20 Km) of the Calabrian Subduction interface based on the interpretation of ca. 60 seismic reflection profiles, and its tentative connection with the deeper slab (> 40 km), constrained by the seismicity distribution. The seismic profiles were mostly provided in the collaborative framework between Spectrum and INGV (CA-60). The three-dimensional reconstruction highlights the detailed geometry and roughness of the subduction interface. Of particular interest is also the western lateral boundary of the subduction interface where a STEP-like fault system has been characterized in detail.