On the ratio of dynamic topography and gravity anomalies in a dynamic Earth
- 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
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@article{id2162, author = {Colli, Lorenzo and Ghelichkhan, Siavash and Bunge, Hans-Peter}, doi = {10.1002/2016GL067929}, journal = {Geophysical Research Letters}, language = {en}, number = {6}, pages = {2510{\textendash}2516}, title = {On the ratio of dynamic topography and gravity anomalies in a dynamic Earth}, volume = {43}, year = {2016}, }
- EndNote
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%O Journal Article %A Colli, Lorenzo %A Ghelichkhan, Siavash %A Bunge, Hans-Peter %R 10.1002/2016GL067929 %J Geophysical Research Letters %G en %N 6 %P 2510–2516 %T On the ratio of dynamic topography and gravity anomalies in a dynamic Earth %V 43 %D 2016