Active tectonics of the İzmit Gulf (NE Marmara Sea): from high resolution seismic and multi-beam bathymetry data

Several active faults were determined in the Gulf of Izmit, using high-resolution shallow seismic and multi-beam bathymetry data. One of them is a buried fault (Fault 2), following central axis of the gulf, which forms the current morphology within its releasing and restraining bends. Releasing bends control the current morphology of the sub-basins. Also restraining bends form folds in the central basin and a thrust in the western basin. A left step over between two strikeslip faults (Faults 2 and 11) creates a transpressional area. Therefore, Hersek and Catal deltas are uplifted. It is determined that Fault 2 could not be related to the origination of the gulf because it cuts all basins and ridges, thus, present geometry of the Fault 2 is not suitable for the initial formation of the gulf. From this point of view, the Fault 2 is initiated recently compared to the whole North Anatolian Fault Zone (NAFZ) in the Marmara Sea. Therefore, Fault 2 is recognised as a new rupture of the NAFZ probably active since the end of the last glacial ice period.