Figure 8 Map of P-wave velocities in our tomography result at
depths of (a) 25 km, (b) 30 km, (c) 35 km, and (d) 40 km. Map features
are the same as in Figure 4. Note the different color bar ranges for
(a-b) and (c-d).
There are regions in the lower crust with rather low P-wave velocities,
even below 6.0 km/s, such as the area around 26°N in the Sichuan-Yunnan
Rhombic Block; while high velocities can be found in the Sichuan Basin
with patches of velocities above 7.2 km/s (Figure 8). In the uppermost
mantle, the low-velocity zones with values lower than 7.5 km/s can be
found above depth of 55 km and the southeast margin of the low-velocity
zone has extremely high velocities above 8.3 km/s (Figure 9).