HR: 12:05h
AN: G31C-08    [PDF]
TI: Mantle Lateral Variations and Earth Tides
AU: * Metivier, L
EM: lalmetiv@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4, place Jussieu, Paris, 75005 France
AU: Greff-Lefftz, M
EM: greff@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4, place Jussieu, Paris, 75005 France
AU: Diament, M
EM: diament@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4, place Jussieu, Paris, 75005 France
AB: Earth strain and gravity responses to tides or atmospheric loads, are generally calculated assuming radially stratified earth models, and at hydrostatic equilibrium. However, some local observations show unexplained perturbations on the tidal gravity signal. A possible cause for those perturbations may be the neglect of rheology and density lateral variations as well as the non hydrostaticity of the Earth. We have investigated a non radially symmetrical earth numerical model with the intent to study the earth response to low frequency forcings. This model uses a finite element method (spectral elements) developed on the cubed sphere mesh (Chaljub et al., 2003 ; Ronchi et al., 1996), and has resolved the static gravito-elasticity equations. The non-hydrostaticity has been taken into consideration by a first order perturbation theory. As a first validation of our model, we computed the M2 and M3 tidal earth response for a radially stratified model: the Preliminary Referential Earth Model. We obtained, as expected, PREM Love numbers with a very good accuracy. As a second validation, we calculated the effect of ellipticity of the Earth and compared, for homogeneous model or for PREM, our numerical results with analytical solutions (using Maple computations), or literature solutions. Finally, as first applications, we have investigated the influence of the lateral variations induced by oceanic -continental crust distribution, and the possible influence of a mega-plume on gravity tide. In the future, we also intend to extend our approach to more local studies, for features affected by other forces than Earth tides.
DE: 1227 Planetary geodesy and gravity (5420, 5714, 6019)
DE: 1234 Regional and global gravity anomalies and Earth structure
DE: 1249 Tides--Earth
DE: 3230 Numerical solutions
DE: 7207 Core and mantle
SC: Geodesy [G]
MN: 2003 Fall Meeting