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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]

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.

Don L. Anderson and Adam M. Dziewonski constructed the Preliminary Reference Earth Model by jointly fitting seismic travel times, normal-mode observations, total mass and moment of inertia.^[ref]

The model supplies mutually consistent reference profiles of elastic properties, density and attenuation. It also incorporates frequency dependence and upper-mantle anisotropy where required by the observations.

A one-dimensional reference model combining elastic wave speeds, density and attenuation, developed by Adam M. Dziewonski and Don L. Anderson. It incorporates joint seismic and global integral constraints rather than treating density as a direct travel-time measurement.

The Solid Earth is the rocky interior-and-surface system of Earth, including its crust, mantle and metallic core. The term includes the liquid outer core of the Earth as well as the solid inner core. Mechanical classifications overlap these compositional layers: the lithosphere contains the crust and the relatively rigid uppermost mantle.

The response also depends on timescale. The mantle supports elastic waves on seismic timescales while undergoing slow mantle flow over geological times. The outer core's liquid response prevents propagation of bulk S waves, whereas compressional P waves can propagate through it. These contrasting responses help constrain the internal structure through seismic waves.

A quantitative reference describes radial profiles of mass density and elastic wave speeds. The Preliminary Reference Earth Model, developed by Adam M. Dziewonski and Don L. Anderson, combines wave observations with global constraints such as Earth's mass and moment of inertia. Its averaged layers are a reference for interpreting departures observed in the real, laterally varying Earth.^[ref]