Tectonics of the buried Kırklareli Fault, Thrace Region, NW Turkey

Abstract

The study investigated the geometry, seismicity and kinematics of the Kırklareli Fault (KF) by using drilling, seismic reflection and field data. The KF, located in the Thrace Region, NW Turkey, is a buried fault that forms a morphological boundary between the Strandzha Mountains and the Ergene Basin. It has lithological and morphological importance in the region. Although there were some destructive earthquakes in the basin historically, the magnitude of the largest earthquake measured instrumentally was only 4.6. Earthquake data obtained from the Kandilli Observatory and Earthquake Research Institute indicate that the epicentres are concentrated along the KF. Deep borehole data show a total vertical displacement of 223 m over the last 2 Ma. Displacement calculations indicated that the KF moves with a normal displacement of at least 0.1 mm/year. The seismic profile verified the existence of the KF. Kinematic analysis of measurements on bedding planes of a formation near the KF demonstrates N105° direction. The activeness and existence of the hangingwall and footwall of the KF are discussed on the basis of morphometric analyses and geomorphic indices. The two geomorphic indices (SL and Vf) show that tectonism effects the morphology. The KF has normal fault geometry according to drilling, seismological and GPS data, geomorphic indices and field observations.