HR: 0800h
AN: S41C-1013    [Abstracts]
TI: Towards Higher Resolution Global Mantle Waveform Tomography
AU: * Shulgin, A A
EM: alexey@seismo.berkeley.edu
AF: Seismological Laboratory, University of California, Berkeley, 307 McCone Hall, Berkeley, CA 94720 United States
AU: Romanowicz, B
EM: barbara@seismo.berkeley.edu
AF: Seismological Laboratory, University of California, Berkeley, 307 McCone Hall, Berkeley, CA 94720 United States
AB: Over the last 10 years, we have developed several generations of three-dimensional elastic and anelastic models of the earth's mantle, based on the inversion of surface and body waveforms using an asymptotic normal mode coupling approach (NACT, Li and Romanowicz, 1996). Until now, the shortest period of analysis of the body waveforms was 32 sec, and we have assumed standard scaling relations between compressional and shear velocities to obtain isotropic and radially anisotropic models of the whole mantle. We have found, surprisingly, that our waveforms have some - albeit weak - ability to resolve the topography of major mantle discontinuities. In order to improve the resolution of our models, extract P velocity information, as well as obtain better constraints on discontinuity topography, it is necessary to extend the analysis to shorter periods. This presents some computational challenges, as the number of coupling terms that need to be included increases rapidly with frequency. It also leads us to rethink our data selection strategy, in particular to allow larger time shifts between observed waveforms and synthetic ones. The latter are computed for a reference earth model and used in an automatic pre-selection step. We present progress in the development of a 3D elastic mantle model based on three component body waveforms down to 16 sec and surface waveforms down to 60 sec.
DE: 7203 Body waves
DE: 7208 Mantle (1212, 1213, 8124)
DE: 7270 Tomography (6982, 8180)
SC: Seismology [S]
MN: Fall Meeting 2005