Reliable knowledge of seismic anisotropy in the mantle can provide invaluable insights into complex tectonics and geodynamics in Anatolia controlled by intricate plate interactions across the region. However, the 3D variations in seismic anisotropy within the crust and upper mantle beneath this area remain poorly constrained. In the present study, we performed splitting intensity (SI) tomography technique, using over 25,000 SI measurements from SKS/SKKS waves recorded at 690 seismic stations, to map lateral and vertical variation of anisotropy that is essential for accurate geodynamic interpretations for Eastern Mediterranean. Our tomographic images show large‐scale mantle flow at asthenospheric depths, oriented in east‐west and northeast‐southwest directions. This flow pattern can be attributed to basal drag forces, which play an important role in driving the westward motion of the Anatolian plate. The strong azimuthal anisotropy in the back‐arc region of the Hellenic subduction zone, with trench‐perpendicular orientation, highlights the significant impact of trench retreat and rollback of the African lithosphere on deformations in the mantle lithosphere and asthenosphere beneath the Aegean region and western Türkiye. The observed weak azimuthal anisotropy, on the other hand, is largely identified across various depths beneath Quaternary volcanoes in the Central and East Anatolian Volcanic Provinces and along the Cyprus subducting slab in the upper mantle. Our numerical tests prove that these weak anomalies may result from plunging/vertical anisotropy associated with upwelling and/or downwelling mantle in central and eastern Anatolia. Plain Language Summary: The Eastern Mediterranean region is known for its complex tectonic and geodynamic processes, driven by the interactions of multiple tectonic plates. While numerical models have shown that changes in subduction can affect how the mantle flows beneath the Earth's surface, the details of lateral and vertical variations of mantle flow remain debated. Our study used the SI tomography technique by analyzing over 25,000 SI measurements from 690 seismic stations. This allowed imaging the orientation of anisotropy that can provide hints about the deformation patterns causing seismic anisotropy in the Earth's upper mantle with high precision. Our results provide valuable insights into mantle flow beneath Anatolia that is responsible for the westward extrusion of Anatolia. We also observe notable anisotropic pattern in response to the strong deformation in the back‐arc region of the Hellenic subduction zone, caused by the retreat and rollback of the African plate. In contrast, relatively weak anisotropy were observed under volcanic regions in Central and Eastern Anatolia, as well as along the Cyprus subduction zone. Our synthetic tests suggest this can be due to vertical movements of the mantle material. These findings offer new insights into the forces shaping the region's tectonics and mantle dynamics. Key Points: Splitting intensity (SI) tomography maps 3D upper mantle deformations under the Eastern Mediterranean Sea regionWeak azimuthal anisotropy may result from plunging/vertical anisotropy linked to mantle upwelling or downwelling beneath volcanic provincesBasal drag force beneath the lithosphere significantly contributes the westward motion of the Anatolian plate [ABSTRACT FROM AUTHOR]

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