Crustal Thickness and Vp/Vs Variations Beneath the Karlıova Triple Junction (Eastern Anatolia‑Türkiye) Revealed by Receiver Function Analysis

Abstract

Eastern Anatolia is one of the most tectonically active regions of the Alpine‑Himalayan orogenic belt, shaped by the ongoing Arabia‑Eurasia continental collision and major strike‑slip fault systems. In this study, we constrain the crustal structure beneath the Karlıova Triple Junction‑Bingöl region using teleseismic receiver function analysis combined with H‑𝜅 stacking. We analyze a high‑quality and long‑term dataset recorded by permanent broadband seismic stations of the Kandilli Observatory and Earthquake Research Institute, using teleseismic earthquakes with Mw ≥ 6.2 selected from an initial larger dataset and epicentral distances of 30°‑95°. The results reveal strong lateral variations in crustal thickness, with Moho depths ranging from ~30 km to ~47 km. Stations located along major active fault zones generally exhibit thicker crust. Average crustal Vp/Vs ratios vary between 1.64 and 1.95, indicating significant heterogeneity in crustal elastic properties. Clear Ps conversions and well‑developed crustal multiples confirm the robustness of the results, while additional early arrivals at several stations suggest internal crustal complexity. The observed patterns are consistent with geophysical and geodynamic models suggesting a hot, thinned, and relatively low‑density lithosphere beneath Eastern Anatolia. These results provide a consistent basis for interpreting lithospheric deformation and the relationship between crustal structure and major fault systems in Eastern Anatolia.