Geodynamics of the Western Anatolia-Aegean Region: Linking tectonics and seismicity

Active continental extension in the western Anatolia-Aegean (since approximately 25 Ma) drives exhumation of several metamorphic core complexes, low angle normal (detachment) faulting, and NE-SW and NW-SE trending strike-slip tectonics. However, the causative relationships among these processes and structures remain poorly understood. Here, we use 3-D thermomechanical numerical models to investigate how strain localization evolves in a stretching continent with plate rotations along a vertical axis. Namely, we test the obliquity of extension between 15° and 60°, the extension velocity of 1–2 cm/yr applied at the plate boundary, an initial crustal thickness of 50 km and a lithospheric thickness of 130 km, as well as the temperature gradient. To characterize the geometry of the fault systems, we calculate the Regime Stress Ratio (RSR) from the stress tensor and evaluate it in regions of high strain rate. We reconcile our model results with up-to-date structural features, including velocity fields from GPS, InSAR data, seismic receiver functions, and regional earthquake datasets from various sources. Preliminary results show that obliquity angle and initial layer thicknesses are first order parameters controlling strain localization, while simultaneously generating significant conjugate strike-slip tectonics. This is in accord with the formation of NE-SW and an array of NW-SE trending faults and clustering of earthquakes (relocated between 2010–2025) along the boundaries of the Gediz, Büyük Menderes and Simav grabens. These findings provide a modeling framework that links fault geometries, metamorphic core complex exhumation, and strike-slip deformation to the extensional tectonics and deeper lithospheric structure beneath the region.