ACTIVE TECTONICS OF THE SARIGOL AREA IN THE GEDIZ(ALASEHIR) GRABEN, WESTERN TURKEY

The Gediz (Alasehir) graben is one of the E-W trending grabens of the western Turkey extended terrane. The Sarigol area is located in the southeastern part of the graben and contains from bottom to top metamorphic rocks of Menderes massif, Plio-Pleistocene Asartepe formation and Holocene Alluvium. The Asartepe formation is made up of weakly cemented conglomerate and sandstone additionally; it unconformably overlies the metamorphic rocks.

We observed recent deformational features in the Sarigol area and mapped them on a 1/5000 scale topographic map. The active faults, exposed on the surface, divide the Sarigol area into 3 blocks. One of the faults displaces irrigational channels and roads. It strikes N60W and dips 30 NE and has caused cracks on the walls of many houses. In general, this surface rupture is associated with 20-25 cm slip with the downthrow on the northeastern block. Another fault is located on the southeastern part of the Sarigol area strikes N80W and dips 45 NE. The sliplines on this fault pitches 50 W, indicating oblique slip on this fault. Although the Sarigol area has not been affected by any strong earthquake since 1969 Alasehir earthquake (M=6.9), the presence of these deformational features suggest that the area has experienced microseismic activity. Therefore, we suggest that the eastern and southeastern parts of the Gediz (Alasehir) Graben have seismic risk potential. Our field data also suggest that the northeast directed Cenozoic extensional tectonics is presently continuing in the region.