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On the ratio of dynamic topography and gravity anomalies in a dynamic Earth

Colli, Lorenzo, Siavash Ghelichkhan, and Hans-Peter Bunge (2016), On the ratio of dynamic topography and gravity anomalies in a dynamic Earth, Geophysical Research Letters, 43(6), 2510–2516, doi:10.1002/2016GL067929.

Abstract
Growing evidence from a variety of geologic indicators points to significant topography maintained convectively by viscous stresses in the mantle. However, while gravity is sensitive to dynamically supported topography, there are only small free-air gravity anomalies (<30 mGal) associated with Earth’s long-wavelength topography. This has been used to suggest that surface heights computed assuming a complete isostatic equilibrium provide a good approximation to observed topography. Here we show that the apparent paradox is resolved by the well-established formalism of global, self-gravitating, viscously stratified Earth models. The models predict a complex relation between dynamic topography, mass and gravity anomalies that is not summarized by a constant admittance — i.e., ratio of gravity anomalies to surface deflections — as one would infer from analytic flow solutions formulated in a half space. Our results suggest that sizable dynamic topography may exist without a corresponding gravity signal.
BibTeX
@article{id2162,
  author = {Lorenzo Colli and Siavash Ghelichkhan and Hans-Peter Bunge},
  journal = {Geophysical Research Letters},
  month = {mar},
  number = {6},
  pages = {2510{--}2516},
  title = {{On the ratio of dynamic topography and gravity anomalies in a dynamic Earth}},
  volume = {43},
  year = {2016},
  doi = {10.1002/2016GL067929},
}
EndNote
%0 Journal Article
%A Colli, Lorenzo
%A Ghelichkhan, Siavash
%A Bunge, Hans-Peter
%D 2016
%N 6
%V 43
%J Geophysical Research Letters
%P 2510–2516
%T On the ratio of dynamic topography and gravity anomalies in a dynamic Earth
%8 mar
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Printed 15. Oct 2019 03:24