FIGURE 4.4 Depth cross section showing the African plume as seen in four recent global tomographic models of S velocity: SAW23B16 (Megnin and Romanowicz, 2000), SB4L18 (Masters et al., 1999), S362D1 (Gu et al., 2001), and S20RTS (Ritsema et al., 1999). Although the models differ in detail, they are in agreement on the broad characteristics of this major upwelling. SOURCE: Y.J. Gu, A.M. Dziewonski, W.-J. Su, and G. Ekström, Models of the mantle shear velocity and discontinuities in the pattern of lateral heterogeneities, J. Geophys. Res., 106, 11,169-11,199, 2001; G. Masters, H. Bolton, and G. Laske, Joint seismic tomography for P and S velocities: How pervasive are chemical anomalies in the mantle? Eos, Trans. Am. Geophys. Union, 80, S14, 1999; C. Megnin and B. Romanowicz, The 3D shear velocity structure of the mantle from the inversion of body, surface and higher mode waveforms, Geophys. J. Int.,143, 709-728, 2000; J. Ritsema, H. van Heijst, and J. Woodhouse, Complex shear wave velocity structure imaged beneath Africa and Iceland, Science, 286, 1925-1928, 1999. SOURCE: B. Romanowicz and Y. Gung, University of California, Berkeley.