Preliminary reference Earth model

The preliminary reference Earth model (PREM) plots the average of Earth's properties by depth.

[1] It includes a table of Earth properties, including elastic properties, attenuation, density, pressure, and gravity.

PREM has been widely used as the basis for seismic tomography and related global geophysical models.

[2] It incorporates anelastic dispersion and anisotropy and therefore it is frequency-dependent and transversely isotropic for the upper mantle.

PREM was developed by Adam M. Dziewonski and Don L. Anderson in response to guidelines of a "Standard Earth Model Committee" of the International Association of Geodesy (IAG) and the International Association of Seismology and Physics of the Earth's Interior (IASPEI) Other Earth reference models include iasp91[3] and ak135.

Earth's Gravity according to PREM. Green curves show hypothetical Earths with density constant (dashed) and decreasing linearly from center to surface (stippled)