Rotational instabilities of the Earth induced by mantle density anomalies
- Ecole Normale Superieure, Paris (France)
- Universita di Bologna (Italy)
From the seismic tomographic models, the authors estimate the offset between the geographic pole and the main inertial axis. This offset, which is large for a static Earth, is drastically reduced when the dynamical behavior of the mantle is taken into account. For a mantle stratification with a viscosity increase by a factor of about 50, this offset is comparable to what can be estimated on the basis of remanent post-glacial depression. The authors also discuss the rate of polar drift induced by both internal mass heterogeneities and Pleistocenic deglaciation. Contributions from internal sources and ice-sheets disintegration are consistent with the observed secular trend. For high viscosity contrasts, the results are quite insensitive to the phase transition of chemical nature of the upper-lower mantle interface. This study shows that there is no contradiction between the tomographic models of the Earth and their implications for the rotational stability of our planet; the findings also agree with recent analyses of paleomagnetic data.
- OSTI ID:
- 5386791
- Journal Information:
- Geophysical Research Letters (American Geophysical Union); (United States), Vol. 17:5; ISSN 0094-8276
- Country of Publication:
- United States
- Language:
- English
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