Ongoing plate convergence between India and Eurasia provides a natural laboratory for
studying the dynamics of continental collision, a first-order process in the evolution of continents,
regional climate, and natural hazards. In southeastern Tibet, the fast directions of seismic
anisotropy determined using shear-wave splitting analysis correlate with the surficial geology
including major sutures and shear zones and with the surface strain derived from the global
positioning system velocity field. These observations are consistent with a clockwise rotation of
material around the eastern Himalayan syntaxis and suggest coherent distributed lithospheric
deformation beneath much of southeastern Tibet. At the southeastern edge of the Tibetan
Plateau we observe a sharp transition in mantle anisotropy with a change in fast directions to a
consistent E-W direction and a clockwise rotation of the surface velocity, surface strain field, and
fault network toward Burma. Around the eastern Himalayan syntaxis, the coincidence between
structural crustal features, surface strain, and mantle anisotropy suggests that the deformation
in the lithosphere is mechanically coupled across the crust-mantle interface and that the
lower crust is sufficiently strong to transmit stress. At the southeastern margin of the plateau
in Yunnan province, a change in orientation between mantle anisotropy and surface strain suggests
a change in the relationship between crustal and mantle deformation. Lateral variations in
boundary conditions and rheological properties of the lithosphere play an important role in the
geodynamic evolution of the Himalayan orogen and Tibetan Plateau and require the development
of three-dimensional models that incorporate lateral heterogeneity