The GPS velocity field of the Aegean Sea and western Anatolia is used to de
termine crustal deformation strain rates for the period 1988 to 1996. The z
one from the Marmara Sea to the North Aegean Trough is associated with stro
ng right-lateral shear motion, with maximum strain rates of 170 nstrain/a.
In the northern Aegean Sea the extensional deviatoric axes are oriented NNE
-SSW, associated with strain rates reaching 150 nstrain/a, and in western A
natolia varying around N-S with rates of up to 95 nstrain/a. The extensiona
l areas mostly coincide with active graben features. The south-western Aege
an Sea is almost strain-free. In general, the areas of high geodetic strain
rates are accompanied by distinct seismic clusters whereas the strain-free
regions are nearly aseismic.