Fig. 7

P-wave velocity structure along the Line 1 seismic profile and the model structure of Rayinvr program. The red line indicates the reflection boundaries used in the inversion. The red stars indicate the shotpoints (SP). There is no seismic coverage beyond the white dashed lines. The wide-angle reflections P1P, P2P, P3P, P4P, and PmP are generated from boundaries 1, 2, 3, 4, and Moho, respectively. a The velocity structure obtained by the regularized inversion algorithm of the first-arrival traveltimes and Rayinvr program. b The crustal velocity structure obtained by using Rayinvr. c The nodes we used to model the seismic velocity structure of Fig. 7b. The red boxes indicate the nodes used to model the boundaries in the crust, and the blue dots used to indicate the seismic velocity nodes above and beneath the boundaries. The nodes between 0 and 7 km are used to resample the upper crustal model obtained by Pg inversion (0–8 km of Fig. 7a), and they are fixed in the employment of Rayinvr program. The other nodes are adjusted to obtain Fig. 7b with the seismic phases (P1P, P2P, P3P, P4P, PmP and Pn)