Northeast India ranks among the most geodynamically complex regions globally. Harmonic Decomposition of Receiver Functions (HDRF) has proven highly effective in revealing multiple crustal anisotropic or dipping layers with varying orientations. In general, the fast axes of crustal anisotropy align with the motion of the Indian Plate, except near the Kopili Fault and the Indo-Burma Ranges. Our analysis also identifies multiple anisotropic layers in the Assam Valley and Bengal Basin, along with an anisotropic Moho exhibiting varying levels of seismic activity.

The presence of a shallow Moho, combined with stress orientations perpendicular to the observed tilt directions, supports the theory that the Shillong Plateau has been tectonically uplifted. Furthermore, the lateral variations in crustal anisotropy reflect multiple episodes of deformation across Northeast India. The off-strike tilt axes in the Indo-Burma region likely indicate pre-existing mantle flow in the asthenosphere, a feature commonly seen in other subduction zones. Finally, the dehydration of the subducting Indian slab may significantly influence the seismic anisotropy observed in the Indo-Burma Ranges.