3-D VELOCITY STRUCTURE BENEATH THE CRUST AND UPPER MANTLE OF AEGEAN SEA REGION

The region of the Aegean Sea and the surrounding areas in the Eastern Mediterranean lies on the boundary zone between the Eurasian and the African plates. It is a zone of widespread extensive deformation and, therefore, reveals a high level of seismicity. Three-dimensional velocity structure, beneath the crust and upper mantle of the region between 33.0-degrees-N-43.0-degrees-N and 18.0-degrees-E-30.6-degrees-E, is determined. The data used are arrival times of P-waves from 166 earthquakes, recorded at 62 seismological stations. In total, 3973 residual data are inverted. The resultant structure reveals a remarkable contrast of velocity. In the top crustal layer, low velocities are dominant in Western Turkey and on the Greek mainland, while a high velocity zone is dominant in the Ionian Sea and in the southern Aegean Sea. In the upper mantle, high velocity zones dominate along the Hellenic arc, corresponding to the subducting African plate and in the northern part of the region, corresponding to the subducting African plate and in the northern part of the region, corresponding to the margin of Eurasian plate. A low velocity zone is dominant in the Aegean Sea region, where large-scale extension and volcanic activity are predominant, associated with the subduction of the African plate.