Abstract:   Western Anatolia has been deformed by disintegrating under the effect of N-S oriented tensile forces since the Miocene. As a result of this deformation, many depressions have developed in NE-SW and E-W directions. These are Gediz and Büyük Menderes Grabens in E-W direction and Gördes, Selendi and Demirci basins towards north orienting in NE-SW direction. The relation of these basins, developing in the different directions, has been widely discussed. In order to determine the extensions, continuities and depth variations of these intersecting structures, boundary analysis and basement topography methods were applied to the Bouguer gravity data. By using obtained parameters, graben structures were modeled according to the Talwani method. As a result of basement topography and modeling studies, average thickness of the basin fill units varies from about 2 km to about 3 km in the Gediz Graben, and 3-4 km in the middle parts. According to the boundary analysis method, the Gördes, Demirci and Selendi basins at the north continue within the Gediz Graben towards the south. These findings also prove the existence of NE-SW oriented grabens developed in Early Miocene, within the E-W oriented Gediz Graben.