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 an d Eurasian lithosphere has been measured by means of the modem techniq ues of space geodesy using the Global Positioning System (GPS). In ord er to resolve in detail the kinematic field within the active earthqua ke belts of Northwestern Anatolia, two GPS campaigns were carried out across a dense network consisting of 45 sites. Preliminary results rev eal 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 ext ension (average 0.06 ppm/y, maximum 0.21 ppm/y) can be obtained from t he calculated strain field. In the west strike-slip motion trending WS W-ENE is observed. These findings are compared to the stress pattern d erived from seismology and neotectonics.