I carried out P-wave teleseismic tomography and constructed the velocity
structure of the upper mantle in the Tibetan Plateau based on the 58999
P-wave arrivals extracted from 2009 teleseismic events recorded by 721
temporary and 173 permanent seismic stations. A mushroom-shaped
large-scale low-velocity anomaly, which might be associated with the
mantle upwelling, is revealed. The mantle upwelling provides more heat
to the base of the crust, which leads to a more ductile or more easily
deformable lower crust, whereas the three large-scale low-velocity
structures cover almost the entire area of the 80 km depth section,
which implies that a rigid lithosphere is absent. In this situation,
during the northward movement and subduction of the Indian plate, the
ductile lower crust above the hot upper mantle facilitated crustal
deformation and thickened, which led to the uplift of the Tibetan
Plateau.