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We investigated velocity and anisotropic structure of the crust beneath the eastern margin of the Tibetan Plateau to better understand its deformation and evolution mechanism. We performed H‐κ and Pms anisotropy analyses to obtain crustal thickness, Vp/Vs ratio, fast polarization direction, and splitting time from 711 stations, and further conducted quality control using slowness, harmonic and statistical analyses. The Songpan‐Ganzi Block has a large splitting time and a fast polarization direction roughly parallel to the GPS motion and SKS fast direction. It also shows an overall high but complex distribution of Vp/Vs ratio, and large variations in crustal thickness, indicating that crustal deformation is likely caused by crustal shortening and lower crustal flow. The northern Sichuan‐Yunnan Rhombic Block (SYRB) is featured by a thick crust and high Vp/Vs ratio, suggesting that the crust is likely inflated by partial melting lower crustal rocks. The subblock also exhibits a strong azimuthal anisotropy with a splitting time greater than 0.6 s. The fast polarization direction aligns with the nearly N‐S extended direction and rotates clockwise in front of the Emeishan Large Igneous Province (ELIP). The observed anisotropy agrees with aligned amphibole minerals under a simple shear condition, supporting a southward lower crust flow being diverted by the ELIP. Anisotropy measurements on the southern SYRB are less robust and widely scattered, suggesting a deformation mechanism different from the northern SYRB. In addition, the southeastern margin of the Sichuan Basin shows a systematic pattern of crustal anisotropy consistent with a pure shear deformation mechanism. Plain Language Summary: We studied the crustal structure and deformation beneath the eastern edge of the Tibetan Plateau. By analyzing teleseismic data from 727 stations, we measured crust thickness, Vp/Vs ratio, and azimuthal anisotropy using receiver functions. Our findings show a complex crustal behavior pattern in the eastern Tibet margin. In the Songpan‐Ganzi Block, crustal shortening and lower crust flow seem to be causing deformation. The northern Sichuan‐Yunnan Rhombic Block, with its thick crust and high Vp/Vs ratio, appears to be influenced by partial melting of lower crust rocks. And a southward lower crust flow being diverted by the Emeishan Large Igneous Province. The eastern and southern part of this block shows a different pattern, indicating a unique deformation mechanism. Additionally, the southeastern margin of the Sichuan Basin appears to undergo a distinct type of crustal deformation. Key Points: A new crustal model with much more reliable and denser Pms anisotropic measurements is built in the eastern Tibetan MarginSongpan‐Ganzi Block is likely deformed by crustal shortening and lower crustal flowChannel flow may exist in the west low velocity zone (LVZ) while absent at the east LVZ [ABSTRACT FROM AUTHOR]

The strength of radial anisotropy can effectively reveal vertical or horizontal material flow, which may provide significant dynamic implications. The South China Block (SCB) is a classic laboratory to study strong deformation under compression from the surroundings. We construct a radially anisotropic 3‐D shear‐wave model of the entire SCB using multimode surface wave tomography with a lateral resolution of 2.0°. Distinctive structural contrasts are revealed in the S‐wave velocity anomalies in the Cathaysia Block and the Yangtze Craton. In the Cathaysia Block, a low‐velocity anomaly becomes evident with increasing depth, particularly in the VSH model. The Yangtze Craton is, however, characterized by a high‐velocity anomaly, especially in the Sichuan Basin, where the high‐velocity feature can extend down to a depth of 300 km. Interestingly, an abrupt change in radial anisotropy is observed beneath the Sichuan Basin, with positive radial anisotropy (faster VSH) in the uppermost mantle and negative radial anisotropy (faster VSV) at depths from 80 to 250 km. The lower negative anisotropic layer may reflect the directional arrangement of constituent materials caused by eastward compression and erosion of mantle flow under the Tibetan Plateau. In addition, remarkable negative radial anisotropy is found in the asthenosphere beneath Hainan Island and its surroundings. The features beneath Hainan Island and its surroundings may be related to the Hainan mantle plume in the Cenozoic. Plain Language Summary: Seismic radial anisotropy represents that the vertically (VSV) and horizontally (VSH) polarized shear waves propagate at different wave velocities in the Earth's medium, which is useful to reflect the deformation characteristics and the deformation pattern of the medium, so as to constrain the mantle dynamics and tectonic processes of the crust and mantle. In this study, we measure multimode Rayleigh wave and Love wave phase velocity dispersion to construct a 3‐D shear‐wave model with radial anisotropy in the entire South China Block. Our results show that the shear‐wave velocity under the Yangtze Craton is anomalously fast and beneath the Cathaysia Block is anomalously slow. Moreover, we find different manifestations of radial anisotropy in the lithosphere of the Sichuan Basin, in which the negative radial anisotropy of 80–250 km is inferred to be affected by eastward compression and erosion of mantle flow under the Tibetan Plateau. A remarkable negative radial anisotropy beneath the Hainan Island and its surroundings in the asthenosphere is interpreted to reflect the Hainan mantle plume in the Cenozoic. Key Points: An anisotropic shear wave model beneath South China is constructed by multimode surface wave tomography with improved vertical resolutionSichuan basin shows negative radial anisotropy, reflecting the influence of eastward compression and mantle flow under the Tibetan PlateauThe low‐velocity anomaly and strong negative radial anisotropy of the Hainan Island may be related to the Hainan mantle plume [ABSTRACT FROM AUTHOR]