Saha et al.(2021) mapped the 3-D shear wave velocity of the uppermost mantle beneath the Bay of Bengal using fundamental mode Rayleigh wave group velocities calculated along 21,600 crisscrossing paths from cross correlation of ambient noise as well earthquake seismograms. They obtained distinctly different lithospheres beneath the eastern and western Bay of Bengal, on either side of 86\(^{\circ}\)E longitude. The western Bay of Bengal has > 120 km thick layered lithosphere and shear wave velocity of 4.7 km/s beyond 90 km depth whereas the eastern Bay of Bengal has thinner lithosphere (60–75 km) with minimum velocity of \(\sim\) 4.2 km/s, which is anomalously low for an old ocean.

3. Seismic Anisotropy, Crust and Mantle Flow

3.1 Crustal Deformation

3.1.1 Doda - Kishtwar Region, NW Himalaya