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Nature 313, 541-545 (14 February 1985) | doi:10.1038/313541a0; Accepted 29 October 1984

Lower mantle heterogeneity, dynamic topography and the geoid

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

  1. Seismological Laboratory, California Institute of Technology, Pasadena, California 91125, USA
  2. *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.).
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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.