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Time-dependent rotational stability of dynamic planets with elastic lithospheres

Chan, N.-H. and Mitrovica, J. X. and Daradich, A. and Creveling, J. R. and Matsuyama, I. and Stanley, S. (2014) Time-dependent rotational stability of dynamic planets with elastic lithospheres. Journal of Geophysical Research. Planets, 119 (1). pp. 169-188. ISSN 2169-9097.

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True polar wander (TPW), a reorientation of the rotation axis relative to the solid body, is driven by mass redistribution on the surface or within the planet and is stabilized by two aspects of the planet's viscoelastic response: the delayed viscous readjustment of the rotational bulge and the elastic stresses in the lithosphere. The latter, following Willemann (1984), is known as remnant bulge stabilization. In the absence of a remnant bulge, the rotation of a terrestrial planet is said to be inherently unstable. Theoretical treatments have been developed to treat the final (equilibrium) state in this case and the time-dependent TPW toward this state, including nonlinear approaches that assume slow changes in the inertia tensor. Moreover, remnant bulge stabilization has been incorporated into both equilibrium and linearized, time-dependent treatments of rotational stability. We extend the work of Ricard et al. (1993) to derive a nonlinear, time-dependent theory of TPW that incorporates stabilization by both the remnant bulge and viscous readjustment of the rotational bulge. We illustrate the theory using idealized surface loading scenarios applied to models of both Earth and Mars. We demonstrate that the inclusion of remnant bulge stabilization reduces both the amplitude and timescale of TPW relative to calculations in which this stabilization is omitted. Furthermore, given current estimates of mantle viscosity for both planets, our calculations indicate that departures from the equilibrium orientation of the rotation axis in response to forcings with timescale of 1 Myr or greater are significant for Earth but negligible for Mars.

Item Type:Article
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URLURL TypeDescription DOIArticle
Stanley, S.0000-0002-4039-2809
Additional Information:© 2013 American Geophysical Union. Received 18 Jun. 2013 Accepted 14 Dec. 2013 Accepted article online 16 Dec. 2013 Published online 28 Jan. 2014. We thank two anonymous reviewers for their comprehensive and constructive reviews. We acknowledge funding from Harvard University and the Canadian Institute for Advanced Research. This work is also supported in part by the M. Hildred Blewett Fellowship of the American Physical Society,
Funding AgencyGrant Number
Harvard UniversityUNSPECIFIED
Canadian Institute for Advanced Research (CIAR)UNSPECIFIED
American Physical Society M. Hildred Blewett FellowshipUNSPECIFIED
Subject Keywords:rotational stability; true polar wander; Earth; Mars; terrestrial planets; Liouville equation
Issue or Number:1
Record Number:CaltechAUTHORS:20140606-080028558
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Official Citation:Chan, N.-H., J. X. Mitrovica, A. Daradich, J. R. Creveling, I. Matsuyama, and S. Stanley (2014), Time-dependent rotational stability of dynamic planets with elastic lithospheres, J. Geophys. Res. Planets, 119, 169–188, doi:10.1002/2013JE004466
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:46111
Deposited By: Tony Diaz
Deposited On:06 Jun 2014 17:23
Last Modified:09 Mar 2020 13:19

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