Summary We investigate the nature of seismic anisotropy in the Kumaun—Garhwal Himalaya by analyzing the core refracted shear wave splitting phases (SK(K)S, PKS) recorded at 42 broadband seismic stations. The mean fast anisotropy directions are mostly in ∼E-W and a few in the ∼NE-SW directions. The mean delay time decreases progressively from ∼1.0s beneath the Sub Himalaya to ∼0.5s at the Higher Himalaya. The observed seismic anisotropy suggests that the ongoing deformation beneath the Kumaun—Garhwal Himalaya has a large contribution by the relative rotation of the asthenospheric flow by the compression along the Indian Plate motion direction in this collision zone. Also, the southward transportation of the mid-crustal flow is probably responsible for the reduction in the delay times in the MCT zone and further north than in the Sub-to-Lower Himalaya. The splitting parameters indicate a complex pattern of deformation beneath the Kumaun—Garhwal Himalaya with contribution from crust, lithospheric mantle and asthenospheric mantle.

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Abstract. Seismic interferometry can be used to extract useful information about Earth's subsurface from the ambient noise wave field. It is an important new tool for exploring seismically quiescent areas. The method involves extraction of empirical Green's function from the background ambient vibrations of the Earth, followed by computation of group or phase velocity and tomographic imaging. Here we provide a review of seismic interferometry and ambient noise tomography (ANT) and present an example of the method in south India.

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