Nature 313, 541 - 545 (14 February 1985); doi:10.1038/313541a0

Lower mantle heterogeneity, dynamic topography and the geoid

Bradford H. Hager, Robert W. Clayton, Mark A. Richards, Robert P. Comer^* & Adam M. Dziewonski^*

Seismological Laboratory, California Institute of Technology, Pasadena, California 91125, USA
^*Present addresses: Department of Earth and Space Sciences, State University of New York, Stony Brook, New York 11794, USA (R.P.C.); Department of Geological Sciences, Harvard University, Cambridge, Massachusetts 02138, USA (A.M.D.).

Density contrasts in the lower mantle, inferred using seismic tomography, drive viscous flow; this results in kilometres of dynamically maintained topography at the core−mantle boundary and at the Earth's surface. The total gravity field due to interior density contrasts and dynamic boundary topography predicts the longest-wavelength components of the geoid remarkably well. Neglecting dynamic surface deformation leads to geoid anomalies of opposite sign to those observed.

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