6. Conclusions
The results from this study reveal significant difference in the S-wave
velocity structure of the crust between the Songpan-Ganzi Block and the
Sichuan Basin. The eastward extrusion of the Songpan-Ganzi Block is
obstructed by the rigid crust beneath the Sichuan Basin, which might be
the cause for stress accumulation and release leading to seismic
activities. Our results also indicate that the eastward material flow
induced by the extrusion of the Tibet Plateau occurred at this region.