Türkiye Jeoloji Bülteni
Baskıda Olan Kabul Edilmiş Makaleler

Abstract: Western Anatolia is widely recognized as one of the fastest-extending continental regions globally, with the Akşehir–Simav Fault System (ASFS) constituting one of the most seismically active structures within this extensional regime. Representing a segment of the Simav Fault Zone, which forms the northwestern section of the ASFS, theBanaz Fault (BF) was re-evaluated in this study based on structural mapping, paleostress analysis of 155 faultslip data collected from 11 locations, and geodetic data. Rather than a single uniform strand, the ~ 37-km-long BFis redefined as a complex, multi-segmented structure comprising the Gürlek, Kızılcaören, and Derbent segments. Paleostress analysis reveals significant spatial and temporal variations in the local stress field. The northwestern Gürlek segment exhibits dominant right-lateral strike-slip character with sub-horizontal σ1 axis. Southeastward, thefault traces a distinct map-view curvature in to the Kızılcaören and Derbent segments, where the σ1 axis transitions to sub-vertical position, shifting the kinematic mechanism to normal and oblique-slip faulting. Superimposed slickenlines at the Evrendede locality preserve a transition from older, pure normal faulting to younger, right-lateral oblique normal faulting, confirming dynamic, counter-clockwise rotation of the σ3 axis over time.Geological and morphotectonic analyses yield a long-term vertical slip rate of 0.1 mm/yr since the PlioQuaternary, which is consistent with contemporary GNSS strain rates (1-2 mm/yr). The active status of the BF is further substantiated by newly-documented ridge-type travertines running strictly parallel to the fault strike (N55°Wand N40°E). Seismic hazard assessments indicate that while individual segments have the capacity to generate earthquakes ranging from Mw = 6.12 to 6.56, full-segment rupture encompassing the entire zone poses a major seismic risk with potential magnitude of Mw = 6.9. Ultimately, this study demonstrates that extensional horsetail structures mature via superimposed extensional phases, structural segmentation control, systematic displacement partitioning, and dynamic local stress variations (axis rotations), mechanisms that directly dictate deep hydrothermal fluid circulation pathways.

Akşehir-Simav Fault System
Banaz Fault
kinematics
horsetail structure
paleostress
seismic hazard
Western Anatolia

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