Global Positioning System constraints on plate kinematics and dynamics in the eastern Mediterranean and Caucasus

We present and interpret Global Positioning System (GPS) measurements of cr ustal motions for the period 1988-1997 at 189 sites extending east-west fro m the Caucasus mountains to the Adriatic Sea and north-south from the south ern edge of the Eurasian plate to the northern edge of the African plate. S ites on the northern Arabian platform move 18 +/- 2 mm/yr at N25 degrees +/ - 5 degrees W relative to Eurasia, less than the NUVEL-1A circuit closure r ate (25 +/- 1 mm/yr at N21 degrees +/- 7 degrees W). Preliminary motion est imates (1994-1997) for stations located in Egypt on the northeastern part o f Africa show northward motion at 5-6 +/- 2 mm/yr, also slower than NUVEL-1 A estimates (10 +/- 1 mm/yr at N2 degrees +/- 4 degrees E). Eastern Turkey is characterized by distributed deformation, while central Turkey is charac terized by coherent plate motion (internal deformation of <2 mm/yr) involvi ng westward displacement and counterclockwise rotation of the Anatolian pla te. The Anatolian plate is de-coupled from Eurasia along the right-lateral, strike-slip North Anatolian fault (NAF). We derive a best fitting Euler ve ctor for Anatolia-Eurasia motion of 30.7 degrees +/- 0.8 degrees N, 32.6 de grees +/- 0.4 degrees E, 1.2 degrees +/- 0.1 degrees/Myr. The Euler vector gives an upper bound for NAF slip rate of 24 +/- 1 mm/yr. We determine a pr eliminary GPS Arabia-Anatolia Euler vector of 32.9 degrees +/- 1.2 degrees N, 40.3 degrees +/- 1.1 degrees E, 0.8 degrees +/- 0.2 degrees/Myr and an u pper bound on left-lateral slip on the East Anatolian fault (EAF) of 9 +/- 1 mm/yr. The central, and southern Aegean is characterized by coherent moti on (internal deformation of <2 mm/yr) toward the SW at 30 +/- 1 mm/yr relat ive to Eurasia. Stations in the SE aegean deviate significantly from the ov erall motion of the southern Aegean, showing increasing velocities toward t he trench and reaching 10 +/- 1 mm/yr relative to the southern Aegean as a whole.