Adam M. Dziewonski and Don L. Anderson coauthored the Preliminary Reference Earth Model, a radial model constrained by body waves, free oscillations and global integral measurements.[ref]
Preliminary reference Earth model by Adam M. Dziewonski and Don L. Anderson. Abstract and Introduction: data combination and model construction
Combining these data constrains density and elastic properties more strongly than wave speeds alone. The result is a reference for comparing observations, rather than a claim that every location has identical structure.
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