MODES, RATES AND GEOMORPHOLOGICAL CONSEQUENCES OF ACTIVE TECTONICS IN THE MARMARA REGION, NW TURKEY-A CRITICAL OVERVIEW

The Marmara region is a tectonically active belt in NW Turkey, where field evidence of the collusion, escape and strike-slip tectonics is manifested. The effect of tectonics on the modification of coastal and morphological features of NW Turkey is, however extensive, relatively unknown and rarely appreciated.

Active tectonics in the region has normal and reverse forms of dip-slip (namely uplift and subsidence) and strike-slip, as is plainly demonstrated by the 1999 Marmara earthquake sequence along the North Anatolian Fault (NAF). These tectonic effects are related to the geometry of the NAF, the mode of lateral movement along it, and proximity to the fault.The 1999 earthquakes provided data indicating that over a return period of about 250 years seismotectonic strike-slip movements recur up to 5 m and dip-slip movements up to 2.6 m, suggesting the rate of tectonics along the NAF in the Marmara region is on the order of 20 mm/yr for strike-slip and 10 mm/yr for dip-slip movements. These rates are sufficiently large to form during the late Quaternary prominent features of the landscape in the Marmara region.