COMPARISONS OF SEISMIC HETEROGENEITY MODELS AND CONVECTIVE FLOW CALCULATIONS

By comparing models of the Earth's mantle obtained from seismic tomogr aphy with the predictions of convective flow calculations we may inter pret the seismic results in terms of mantle flow scenarios. The result s of such comparisons are consistent with a picture of convective flow in the Earth's mantle in which whole mantle style flow is dominant at present but in which phase transition induced localized layering also exists. In addition, direct examination of the tomographic images sho w regions where the boundary between upper and lower mantle marks a si gnificant discontinuity in heterogeneity while in other regions hetero geneities appear to be continuous across it.