Body tides on a 3-D elastic earth: Toward a tidal tomography

• Published in: Earth and planetary science letters 2009-01, Vol.277 (1), p.86-90
• Main Authors: Latychev, Konstantin, Mitrovica, Jerry X., Ishii, Miaki, Chan, Ngai-Ham, Davis, James L.
• Format: Article
• Language: English
• Subjects: 3-D Earth models; body tides; Marine; seismic tomography
• ISSN: 0012-821X; 1385-013X
• DOI: 10.1016/j.epsl.2008.10.008

The deformational and gravitational response of the Earth to the tide generating potential has generally involved 1-D (i.e., depth varying) Earth models. Progressive improvement in observational constraints on body tides, generated from both ground and space-based surveys, suggests that an examination of the potential impact of lateral variations in Earth structure is warranted. We present a suite of predictions of the body tide response within the semi-diurnal, diurnal and long-period tidal bands computed using a finite-volume numerical code. The calculations adopt 3-D density and elastic structure taken from seismic inferences and, in a subset of the calculations, dynamic topography on the surface and internal interfaces. We find that perturbations in the radial displacement and surface gravity within the semi-diurnal band reach ~ 1 mm and 0.15  µgal, respectively. The perturbations in the diurnal band are comparable to these values, and within the long-period band they are a factor of 3–5 smaller. We also demonstrate that lateral variations in the elastic moduli, which have been ignored in recent work, contribute greater than 50% of the total perturbation. The level of perturbation associated with 3-D structure exceeds the current observational uncertainty obtainable using space-geodetic methods, and this suggests the possibility of performing tidal tomographic inversions of such data.