Structure of the Kaapvaal craton from surface waves

Phase delays of Rayleigh and Love waves from teleseismic earthquakes recorded during the Southern Africa Seismic Experiment have been inverted for upper-mantle seismic velocities along the propagation paths and beneath the station array. Successful models of subarray structure displayed significant radial anisotropy in the uppermost mantle but no shear-wave low-velocity zone, supporting the hypothesis that the lithosphere beneath the Kaapvaal craton is thick. The azimuthal variations of Rayleigh-wave slowness are not consistent with simple models based on SKS splitting observations and anisotropy measurements of Kaapvaal mantle xenoliths. This discrepancy may imply some amount of small-scale heterogeneity in anisotropy.