2.2 P-wave onset time picking and ray path coverage
In this study, we use the onset times of first arriving P waves in the
epicentral distance range of 2.5°-15° to develop the regional P-wave
velocity model. As show in the vertical projections of the ray paths in
Figure 2, the first-arriving P waves in this distance range include the
crustal Pg waves at shorter distances and Pn and upper-mantle diving P
waves at larger distance.