GPS-derived strain rate field within the boundary zones of the Eurasian, African, and Arabian Plates

We use the GPS velocity field (1988-1998) for eastern Mediterranean and Asi a Minor to determine the crustal deformation strain rate field in an area b ounded by 35 degrees N and 43 degrees N, and 20 degrees E and 48 degrees E. We calculate the normal and shear strain rate components associated with t he major faults and compare these qualitatively with seismological data. Un certainties in the calculation of the strain rates reach 50 nstrain yr(-1) in sparsely observed parts of Anatolia, whereas we estimate errors < 20 nst rain yr(-1) in the Aegean and Marmara regions. The largest compressional st rain rate components in the eastern part of the study area occur along the Greater Caucasus mountain front reaching 70 nstrain yr(-1). (1 nstrain yr(- 1) = 0.0317 x 10(-15) s(-1)). The North Anatolian Fault Zone is the dearest feature in the shear strain rate field. It is expressed as a pronounced de xtral strike-slip fault zone, reaching rates of up to 170 nstrain yr(-1). T his holds true also for the Izmit area, where the August 17, 1999, earthqua ke occurred. Central Anatolia is almost strain-free, whereas extension prev ails in western Anatolia. The principal axes of extension vary around the N -S direction with strain rates of up to 85 nstrain yr(-1). These extensiona l areas coincide with graben features and normal faulting earthquakes. The central and southwestern Aegean Sea is strain-free with values far below 40 nstrain yr(-1). The seismic cluster around the Dodekanissa islands, southe astern Aegean Sea, coincides with NW-SE oriented extension, attaining strai n rates of up to 90 nstrain yr(-1). This area of extension also exhibits re cent active volcanism. The entire Hellenic are shows compressional strain r ates perpendicular to the are. The Pliny-Strabo troughs along the eastern s egment of the are show left-lateral shear strain rates reaching 80 nstrain yr(-1) Significant extension is found in central Greece, with a NNE-SSW ori ented maximum of 120 nstrain yr(-1) centered around the Gulf of Corinthos. The Kephalonia Fault Zone in NW Greece is a distinct dextral fault zone, se parating Apulia from the rapidly moving Aegean microplate. Right-lateral sh ear strain rates reach 150 nstrain yr(-1).