CONTINENTAL COLLISION AND BASIN OPENING IN SOUTHERN ITALY - A NEW PLATE SUBDUCTION IN THE TYRRHENIAN SEA

An analysis of the spatial distribution of the seismicity of the southern Tyrrhenian Sea is presented with the aim of putting constraints on the geometry of the complex Benioff zone of this area by relocating the earthquakes that occurred in the period 1985-1990. The data set used in this analysis is based on information from ING, ISC, and NEIS databases. In order to ensure the quality of epi/hypocentral locations, we based our selection of earthquakes on both the available number of P- and S-readings (at least eight P- and two S-pickings) and the epicentral distances of the stations reporting the event (< 5-degrees). Such a selection enabled us to obtain a catalogue of 450 well-located events with focal depths of up to 500 km. The seismogenetic volumes estimated from the distribution of hypocentres of the whole seismicity analysed were interpreted according to a recent geodynamic model proposed for this area. This has led us to the hypothesis of an active NW-SE-oriented subduction of the lithosphere generated and stressed by the opening of the Tyrrhenian Basin.