Seismic anisotropy under Zagros foreland from SKS splitting observations

Abstract. We present SK[K]S splitting measurements from 18 newly deployed seismic stations in the foreland of the Zagros collision zone, providing new insights into asthenospheric flow and lithospheric deformation associated with the Arabian-Eurasian continental collision. Our results reveal two distinct fast-axis orientations: NE-SW in northern Iraq and NW-SE in the Mesopotamian Plain and Persian Gulf. The NE-SW anisotropy in northern Iraq aligns with fast-axis orientations observed in the Iranian-Anatolian Plateau and the azimuth of absolute plate motion, indicating large-scale asthenospheric flow as the primary influence across the northern Middle East. In contrast, the NW-SE anisotropy in the Mesopotamian Plain and Persian Gulf, characterized by smaller splitting times, parallels previously reported Pn anisotropy, suggesting a contribution from lithospheric mantle anisotropy, likely a remnant of past rifting. The influence of asthenospheric flow on the observed seismic anisotropy in this region appears minor. These findings refine our understanding of mantle dynamics and lithosphere-asthenosphere interactions in the Zagros collision zone.