Fig. 6
From: Subducted oceanic crust as the origin of seismically slow lower-mantle structures
Power spectral density plots for S40RTS and the tomographically filtered models as imaged beneath the African plate. Spectral power is normalized to the maximum power at each depth and plotted as a function of wavenumber and radius. Same basic features as for mantle beneath the Pacific except that S40RTS has more power at low wavenumbers in the upper mantle as well as in the lower mantle