The Importance of Multiples in Teleseismic Scattered-Wave Imaging
Abstract
Traditional imaging approaches in solid-earth, passive seismology suffer from the presence of free-surface multiples in the data, which hinder the detection of structure in certain depth ranges. Here, I discuss a recently developed teleseismic migration technique that, unlike traditional approaches, incorporates and relies in large part on free-surface multiples to improve the focusing and resolution of lithospheric structure. The technique involves multichannel inversion of scattered teleseismic body waves recorded at dense seismic arrays. The problem is posed for forward- and back-scattered wavefields generated at discontinuities in a 2D isotropic medium, with the backprojection operator cast as a generalized Radon transform (GRT). The approach allows for the treatment of incident plane waves from arbitrary backazimuths, and recovers estimates of material property perturbations about a smoothly varying reference model. The recovered properties are P and S velocities, which are independently obtained by treating P-P and P-S/S-S interactions at 2-D line-scatterers, respectively. The S-velocity image is constructed by a combined analysis of forward and back-scattered modes, with the latter affording better resolution of planar structure, whereas the P-velocity image relies exclusively back-scattered interactions. Applications to synthetic and field data from Cascadia, Alaska, and the SE Canadian Shield are presented to illustrate the benefits of including multiples in teleseismic imaging.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2005
- Bibcode:
- 2005AGUSM.S33A..04R
- Keywords:
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- 7203 Body wave propagation;
- 7218 Lithosphere and upper mantle;
- 7260 Theory and modeling;
- 7294 Instruments and techniques