Active tectonics and kinematic analysis of Yunak fault zone, Afyon Akşehir graben

The Master's thesis study was conducted on the Yunak Fault Zone. Five segments within the Yunak Fault Zone were mapped for the first time at a scale of 1/25,000. These segments were named Karapınar, Cebrail, Üçkuyu, İncirli, and Ayrıtepe. The geometric, kinematic, and active tectonic properties of these segments were analyzed for the first time. Additionally, within the study area, asismic surface deformations that have occurred in the Tuzlukçu region and its vicinity without destructive earthquakes for the past 7 years were mapped for the first time within the scope of the thesis. The deformation characteristics were analyzed and correlated with the region's tectonic structure. The findings obtained from fieldwork indicate the presence of normal faults with NS, EW, and NE-SW orientations, ranging in length from 3 km to 18 km and in width from 300 m to 4 km, capable of generating earthquakes with moment magnitudes ranging from 5.6 to 6.7. Paleostress analyses conducted within the thesis reveal that the faults in the region were primarily formed by pure strike-slip faulting under the influence of N-S-directed extensional forces and E-W-directed compressional forces during the pre-Quaternary period. However, during the Plio-Quaternary period of extensional tectonism, they were reactivated as inclined/oblique-slip normal faults within a multi-directional extensional tectonic setting involving E-W, NS, and NE-SW orientations. The newly defined Akşehir Sub-Graben is controlled by the inclined Yunak and Mevlütlü Fault Zones and exhibits a cross-graben nature on the hanging block of the Sultandağı Fault. Based on measurements conducted on the asismic surface deformations observed east of the Tuzlukçu Settlement (Çöğürlü), the orientations of the linear fissures and cracks range from N28°E to N10°E, with a general N-S trend north and south of Çöğürlü Village. Fieldwork suggests that the approximately 8 cm/year deformation rate calculated for the asismic surface deformations may have developed on one of the existing but hitherto unknown N-S-oriented fault branches in this region.