HR: 1340h
AN: G43C-1476    [Abstracts]
TI: Mantle dynamics and Length of Day variations
AU: * Greff-Lefftz, M
EM: greff@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4 place Jussieu, Paris, 75005, France
AU: Rouby, H
EM: greff@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4 place Jussieu, Paris, 75005, France
AB: The geological evolution of the Length of Day (LOD) variations is mainly controlled by the frictional tidal torque responsible for the secular deceleration of the Earth rotation velocity and for the removal of the Moon. Superimposed to this variation existing from the early history of the planet, there are, at shorter time-scale (less than one Myr), LOD perturbations induced by the glaciation-deglaciation cycles. Here we investigate the influence of the mantle dynamics on the LOD at the geological time-scale. Using the complete non-linear equations governing the rotational dynamics of a viscous planet, we compute the effects induced by upwelling domes and subducted plates sinking into the mantle on the velocity of the rotation, that is to say on the LOD, and we also discuss the geological variation in the orientation of the rotational axis with respect to a fixed terrestrial frame.
DE: 1213 Earth's interior: dynamics (1507, 7207, 7208, 8115, 8120)
DE: 1239 Earth rotation variations
SC: Geodesy [G]
MN: 2007 Fall Meeting