HR: 0830h
AN: U51B-0001    [PDF]
TI: Non Linear Analysis of Differential Travel Times of PKP Phases and D'' Structure
AU: * Garcia, R
EM: garcia@ipgp.jussieu.fr
AF: IPGP DGSP UMR7096 CNRS, 4, Ave de Neptune, Saint Maur, 94107 France
AU: Tkalcic, H
EM: tkalcic1@llnl.gov
AF: Lawrence Livermore National Laboratory, P.O. Box 808, L-206, Livermore, CA 94551 United States
AU: Chevrot, S
EM: chevrot@pontos.cst.cnes.fr
AF: LDTP UMR5562 CNRS, Observatoire Midi-Pyr‚n‚es 14, Ave E. Belin, Toulouse, 31400 France
AB: The triplication of PKP core phases has been widely used to extract information on the structure of both the inner core and the base of the mantle. We present a new method that performs a non linear inversion of the 3 main core phases waveforms (PKP(DF), PKP(BC) and PKP(AB)). The differential travel times between these body waves are measured with high accuracy even when they interfere on the records, or when pPKP depth phases are present. This property allows us to investigate the epicentral distance range 146-149 degrees previously hidden by the interference between the 3 core phases, and new ray paths associated to shallow events. Preliminary results reveal strong variations of the differential travel times residuals involving the PKP(AB) phase, that could be related to short wavelength heterogeneities at the base of the mantle. These observations are presented for particularly well resolved regions of the base of the mantle and interpreted in terms of geodynamic processes at the Core-Mantle boundary.
DE: 3260 Inverse theory
DE: 7203 Body wave propagation
DE: 7207 Core and mantle
DE: 7294 Instruments and techniques
SC: U
MN: 2003 Fall Meeting