HR: 16:00h
AN: T54A-01 INVITED     [Abstracts]
TI: The Anisotropy of the Inner Core: A Review
AU: * Souriau, A
EM: Annie.Souriau@cnes.fr
AF: Observatoire Midi-Pyrenees CNRS/LDTP, 14 Avenue Edouard Belin, Toulouse, F-31130 France
AB: The anisotropy of the inner core has been identified about 20 years ago from both body wave propagation and eigenmode splitting. The P-wave velocity is about 3% higher for waves travelling parallel to Earth rotation axis than for waves travelling parallel to equatorial plane. Since this discovery, many controversial results about the inner core anisotropy properties have been published, and even the existence of anisotropy itself has been questioned. In this review, I will present and discuss the main results concerning the inner core anisotropy properties, in particular: 1) The radial distribution of the anisotropy, with the absence of anisotropy at the top and the probable existence of a deep inner-core with a different anisotropy orientation; 2) the problematic longitudinal pattern of the inner core anisotropy; 3) the possibility of an anisotropy in attenuation. The possible artefacts due to mantle heterogeneities and to liquid core will be discussed, as well as the compatibility between eigenmodes and body waves. Alternative explanations with inner core heterogeneities will also be considered. Finally, the resolution of the models will be discussed, as well as the modification of the radial and anisotropic mean models when P-wave sensitivity kernels are taken into account.
DE: 8115 Core processes (1507)
DE: 8124 Earth's interior--composition and state (old 8105)
DE: 7203 Body wave propagation
DE: 7207 Core and mantle
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting