Abstract: The Gediz, Büyük Menderes and Küçük Menderes grabens have been formed in relation to detachment faulting. The Gediz graben, which is active at the present time, is a WNW - ESE trending half graben. The youngest graben fill is the sediment of the Salihli- Alaşehir plain. The initation of the Gediz graben has started with the activity of the Karadut fault which is the youngest detachment fault of the region. The low - angle detachment fault of the Karadut which cut the Early Miocene granodiorite has produced acataklastic - mylonitic zone of a regional extent. The shear sense indicators along this zone were the product of the same kinematicactivity and the tectonic transport has occurred along top to the north - northest direction.The footwall section of the Karadut fault consists of schists and marbles of the Menderes Massif In thefootwall section granodiorite stocks have been emp laceddue to the activity of the fault. The hanging - wall section consists of rocks of the Menderes Massifand a Neogene sedimentary succession. Along the surface of the Karadut fault, erosion of the Neogene rocks has exposed in someplaces the hanging - wall slivers, which are gneisses and schists of the Menderes massifIn the Itanging - wall of the Karadut fault, detrilal sedimentary succesions of graben -fill were deposited and they were controlled both by blocks of the initial fault system and also by the new high - angle syntetic faults. The region is still active presently as theoccurrences of earthquakes along of the graben indicate.