BACK ARCS BASINS AND P-WAVE CRUSTAL VELOCITY IN THE IONIAN AND AEGEANREGIONS

Tomographic images of the lower crust and uppermost mantle beneath the Central Mediterranean have been obtained from arrival times of region al earthquakes. We find a low velocity belt at about 25 km beneath the Hellenic Arc. A low velocity anomaly at a depth of 40 km extends unde r the Aegean back arc basin. High velocities are present at Moho depth beneath the Ionian Sea close to the Calabrian and Aegean arcs and und er the Aegean Sea. The results suggest a close relation between P wave crustal velocity and the subduction systems of the studied area.