“…Thus, for each station pair, nine cross‐correlation functions are calculated (Z‐Z, Z‐E, Z‐E, N‐Z, N‐N, N‐E, E‐Z, E‐N, E‐E). We then measure phase velocity dispersion curves from the symmetrical component of the Z‐Z cross‐correlation functions for all station pairs by an automatic frequency‐time analysis (e.g., Dziewonski et al., 1969; Herrin & Goforth, 1977; Levshin & Ritzwoller, 2001). With those interstation dispersion curves, we adopt the Fast‐Marching Method (Kennett et al., 1988; Rawlinson & Sambridge, 2004a, 2004b) to perform the tomographic inversion at periods between 6 and 40 s. The tomographic results are shown in Figure 2.…”