GLOBAL POSITIONING SYSTEM (GPS) ESTIMATES OF CRUSTAL DEFORMATION IN THE MARMARA SEA REGION, NORTHWESTERN ANATOLIA

In the Marmara Sea region the relative motion between the Anatolian and Eurasian lithosphere has been measured by means of the modem techniques of space geodesy using the Global Positioning System (GPS). In order to resolve in detail the kinematic field within the active earthquake belts of Northwestern Anatolia, two GPS campaigns were carried out across a dense network consisting of 45 sites. Preliminary results reveal horizontal westward motion of Anatolia relative to Eurasia of 2.4 cm/y on average that runs along the western end of the North Anatolian Fault Zone. E-W oriented right-lateral strike-slip movement (average 0.06 ppm/y, maximum 0.13 ppm/y) (1 ppm/y = 1 mustrain/y) and NE-SW extension (average 0.06 ppm/y, maximum 0.21 ppm/y) can be obtained from the calculated strain field. In the west strike-slip motion trending WSW-ENE is observed. These findings are compared to the stress pattern derived from seismology and neotectonics.