IASPEI - Picture Gallery

IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS011 Poster presentation 2137
Earth’s structure with the gravimetric tomography method
Dr. Rudolf Greku
IASPEI IASPEI
Alexander A. Kulikov, Tatyana R. Greku
Experienced geophysicists supposed a relationship between depth of disturbing layers and the geoid
harmonics [1, 2]. In later researches on modeling of the Earth the geoid was used as observable
referenced data to integrate their or compare with seismic or geodynamic data [3, 4]. The inverse
decision of the geopotential-density problem was proposed in a book [5]. Our gravimetric tomography
technique is based on realization of this algorithm for determination of harmonic dense anomalies
(relatively the PREM density model) through the spherical harmonics of the EGM96 gravity potential
model. Spherical harmonics are used also for determination of the layers depths disturbing geopotential.
Maps of the lateral distribution of density inhomogeneities at different layers and vertical cross sections
along characteristic directions over the world, dynamic features within the Antarctic and Arctic Polar
regions in all range of depths up to 5300 are presented in the paper. Comparison of the gravimetric
tomography data with the seismic tomography data from [6, 7, 8, 9] is given. In particular, the
gravimetric tomography data are coordinated with seismic images of the Antarctic regions from the
work [9]. It is shown that the main structural bodies are similar by signs and the spatial distribution at
the lateral slices in depths of 150 km and 400 km. Areas with low-velocity anomalies are corresponding
to the less dense structures by the gravimetric tomography and vice versa. But the areal enclosing of
different structures is not coincided everywhere. It concerns especially to the shallower crustal layers
where the seismic tomography models have a less resolution. The plume zones can be also visible with
the gravimetric tomography at deeper layers. Known low-velocity layer on the core-mantle boundary
underneath the Pacific and Africa [10] is indistinguishable by the gravimetric tomography density
models. At the same time these models are coordinated here with the models of density within the
mantle from [8]. 1. Allan R.R., Nature, 1975, 236: 22. 2. Gainanov A.G., 1981, Geology and Geophysics
of the Eastern Indian Ocean Floor, Moscow, Nauka, 256 (in Russian). 3. Ricard Y., Richards M., Lithgow-
Bertelloni C., Le Stunff Y., 1993, J. Geophys. Res., 98, 21895. 4. Forte A.M., Woodward R.L., Dziewonski
A.M., 1994, J. Geophys. Res., 99, 21857. 5. Moritz H., 1990, The Figure of the Earth, Wichmann,
Karlsruhe. 6. Dziewonski A.M., Hager B.H., OConnell R.J., 1977, J. Geophys. Res., 82, 239. 7.
Romanowicz B., 2003, Annu. Rev. Earth Planet. Sci., 31:303. 8. Ishii M., Trompb J., 2004, Physics of the
Earth and Planetary Interiors, 146: 113. 9. Ritzwoller M.H., Shapiro N.M., Levshin A.L., Leahy G.M.,
2001, J. Geophys. Res., 106, 30645. 10. Dziewonski, A.M., 1984, J. Geophys. Res., 89, 5929.
Keywords: tomography, structure, geoid