Abstract
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+-5W relative to Eurasia, less than the NUVEL-1A
circuit 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+-1 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 Anatolian fault (NAF).
We derive a best fitting Euler vector for Anatolia-Eurasia motion
of 30.7+-0.8N, 32.6+-0.4E, 1.2+-0.1 deg/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, 0.8+-0.2
deg/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.
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