GPS Measurements along the North Anatolian Fault Zone on the Mid-Anatolia Segment

The North Anatolian Fault (NAF) is one of the longest active strike slip systems. Slip rate of the NAF was estimated from the GPS data as 20-24mm/yr approximately from previous studies. One of the important features of the NAF is seen in the central part. Here NAF consists of southward splitting concave branches. These splines generally have right-lateral slip and can be compared with Riedel fractures. The important splays are Sungurlu, Merzifon and Lacin faults. A new project "Determination of Kinematics along the North Anatolian Fault Branch between Ladik and Ilgaz with GPS Measurements", founded by The Scientific and Technical Research Council of Turkey (TUBITAK) and Istanbul Technical University (ITU) Research Fund has been carried out in order to determine the magnitude and direction of the block movements in the region by using GPS since 2001. The knowledge about the neotectonics of the region with the contributions of geology and seismology after the GPS campaigns is expected to provide further information on the assessment of the earthquake potential. To determine tectonic characteristic of the region, a network having sixteen sites was established. Measurements with three day pairs were performed in six days at two stages. The duration of measurement in each day was about 8 hours with an interval of 30 seconds. All stations were observed for at least three days. The GPS measurements for four campaigns were processed using GAMIT/GLOBK software package. This paper examines the results from the four GPS campaigns. According to the obtained GPS velocity vectors, the movement of the region has the same direction with Anatolian plate escaping from East to West. All stations on the north of the NAF (KRGI (Kargi{dotless}), IHGZ (Ihsangazi), KVAK (Kavak) and GOL1 (Gol)) have smaller vectors than the stations on the south. The magnitude and direction differences between velocity vectors present the anticlockwise movement of the Anatolian plate with the information abut the movements of the blocks in the region.