HR: 08:55h
AN: S51E-04    [Abstracts]
TI: Interpretation of Images from Joint Body-Wave Tomography
AU: * Kennett, B L
EM: Brian.Kennett@anu.edu.au
AF: Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200 Australia
AU: Gorbatov, A
EM: alexei@jamstec.go.jp
AF: IFREE, Jamstec, Yokosuka, 237-0061 Japan
AB: Joint body-wave tomography exploiting the arrival times of both P and S waves can provide high-resolution images of the bulk-sound and shear wavespeed for more than half of the mantle. The use of source-and station pairs for which both P and S arrivals have been picked provides strong quality control on the data and ensures comparable coverage of P and S paths. Current and past subduction is generally marked by distinct fast shear wavespeed anomalies with a variable bulk-sound speed component, which in the upper mantle appears to have significant dependence on the age of the subducted lithosphere. Orogenic belts generally show an anti-correlation of bulk-sound and shear wavespeed heterogeneity indicating that the S waves are more strongly affected than the P waves. However, there are intriguing features to be found elsewhere in the 3-D structure, such as the anti-correlation of bulk-sound and shear wavespeed features in some parts of the transition zone, e.g., near western Australia, and the rather strong signature of deep penetration for both the Tethys and Farallon slabs in shear wavespeed but not in bulk-sound. Insight into character of the images for both wavespeeds can be found from the application of finite strain theory for the increment from the hydrostatic state of the reference model in a second order Birch-Murnaghan development.
DE: 8180 Tomography
DE: 8124 Earth's interior--composition and state (old 8105)
DE: 7203 Body wave propagation
SC: Seismology [S]
MN: 2004 AGU Fall Meeting