Fig. 21

a Phase velocities of the fundamental (0th) and first-higher modes of surface waves for the modified PREM (Dziewonski and Anderson 1981). The sudden phase velocity decrease marked by the ellipse corresponds to the transition of modal energy from solid to ocean. b, c Sensitivities of phase velocities to P-wave and S-wave velocities (\(K_{\alpha }\) and \(K_{\beta }\), respectively). The two lines in each panel show the depths of the seafloor and Moho. Taken from Takeo et al. (2013)