Paul and Ravi Kumar (2022) identified salient features of the mantle
beneath the Indian Ocean and Ross Sea, by analyzing 8 global tomographic
models. Their study indicates low velocity anomalies of dVs
~1.1% in the ~400–680 km depth range
and inconsistent high velocity anomalies of dVs ≥ 1% at depths below
1600 km beneath both Indian Ocean and Ross Sea. A consistent low
velocity structure throughout the mantle beneath the southwestern Indian
Ocean and east Africa is associated with a plume from the African LLSVP.
Forward modeling of the Geoid indicated that the E-W extent of the IOGL,
influenced by upper mantle anomalies, could be precisely predicted,
however, the N-S extent is underestimated since the lower mantle
anomalies are inconsistent.
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°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
~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