| Abstract: | P-wave velocities in the Tyrrhenian mantle have been determined for the 230–480 km depth range. Analysis of P-wave travel times for a set of Tyrrhenian deep earthquakes gives a velocity-distribution law which shows different behaviours in the 230–300 km and 300–480 km depth intervals. For the first interval the velocity gradient is 0.64 · 10−2 sec−1 and for the second one it is 0.59 · 10−2 sec−1. At a depth of 300 km the velocity decreases rapidly from 8.75 to 8.43 km/sec.The results have been analyzed in the framework of a Tyrrhenian structural model characterized by a lithospheric slab dipping 55–60° in the WNW direction.It is also pointed out that the analysis of some geodynamic features of the slabs of Pacific island arcs carried out by Oliver et al. (1973) and Sleep (1973) can be applied to the Tyrrhenian mantle geodynamic features. |
