Active or passive subduction at the Calabrian arc

Abstract

The comprehensive list of earthquakes with focal depth > 50 km in the subduction zone of the Calabrian Arc is presented. The seismic zone dips towards the NW and strikes from SW-NE in the upper part to S-N at the deeper levels down to 490 km. The main activity occurs between depths of 220 and 350 km; relative minima are found above and below. The focal mechanisms of the earthquakes show a common feature in the position of one of the possible fault planes, and are indicative of a common stress pattern for the whole zone below 200 km. Subduction in the mantle is of the passive kind and seems to be determined by gravity only. This is not yet clear for the horizontal movements which in the first place generated the zone of subduction.