Global Positioning System Constraints on the Plate Kinematics and Dynamics in Turkish Region

We present and interpret Global Positioning System (GPS) measurements of
crustal motions for the period 1988-1997 at 189 sites extending east-west from
the Caucasus mountains to the Adriatic Sea and north-south from the southern
edge of the Eurasian plate to the northern edge of the African plate. Sites on
the northern Arabian platform move 18+- 2 mm/yr at N25 +- 5 W relative to
Eurasia, less than the NUVEL -1A circut closure rate ( 25+- 1 mm/yr at N21 +-
7W). Preliminary motion estimates (1994 -1997) for stations located in Egypt on
the northeastern part of Africa show northward motion at 5 -6 +- 2 mm/yr, also
slower than NUVEL-1A estimates ( 10 +- mm/yr at N2 +- 4E). Eastern Turkey is
characterized by distributed deformation, while central Turkey is characterized
by coherent plate motion (internal deformation of < 2 mm/yr) involving westward
displacement and counterclockwise rotation of the Anatolian plate. The
Anatolian plate is de-coupled from Eurasia along the right-lateral,
strike-slip North Anatolia fault (NAF). We derive a best fitting Euler vector
for Anatolia-Eurasia motion of 30.7 +- .8N, 32.6 +- 1.2E, 1.2+- .1/Myr. The
Euler vector gives an upper bound for NAF slip rate of 24 +- 1 mm/yr. We
determine a preliminary GPS Arabia-Anatolia Euler vector of 32.9 +- 1.2N, 40.3
+- 1.1E, .8 +- .2 /Myr and an upper 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 motion (internal deformation of <2 mm/yr) toward the
SW at 30 +- 1 mm/yr relative to Eurasia. Stations in the SE Aegean deviate
significantly from the overall motion of the southern Aegean, showing
increasing velocities toward the trench and reaching 10 +- 1 mm/yr relative to
the southern Aegean as a whole.