HR: 1340h
AN: S33A-1091    [Abstracts]
TI: Teleseismic Imaging with Wave Equation Migration
AU: * Wilson, C K
EM: wilsonck@stanford.edu
AF: Stanford University Department of Geophysics, Panama Mall, Stanford, CA 94305 United States
AU: Shragge, J
EM: jeff@sep.stanford.edu
AF: Stanford University Department of Geophysics, Panama Mall, Stanford, CA 94305 United States
AU: Artman, B
EM: brad@sep.stanford.edu
AF: Stanford University Department of Geophysics, Panama Mall, Stanford, CA 94305 United States
AB: We demonstrate the utility of wave equation migration for lithospheric imaging with teleseismic phases by showing results using from both example synthetic and real datasets. Employing the shot-profile formulation of wave equation migration allows us to independently propagate the source and receiver wavefields using a Fourier domain downward continuation operator. Before propagation, we separate the P-Sv-Sh components of the receiver wavefield results by applying the free-surface transfer matrix. Following separation, we model the source wavefield in one of two ways: (1) the P component is assumed to be a direct measure of the source wavefield as in more traditional receiver function ananlysis, or (2) the source wavefield is modeled as a band limited plane wave with moveout and relative delays similar to that of the direct P arrival. After the choise of source representation and independednt propagation of both wavefields we compare them at each image point by calculating the zero-lag of the cross-corrrelation or deconvolution of the two wavefields. Where the two wavefields are coincident (e.g. at a locus of scattering), the wavefields are similar and produce an image point with non-zero amplitude. Fundamentally, we perform the same operations on the recorded data as in more traditional receiver function and common conversion point procedures (e.g. deconvolution followed by depth migration) except we reverse the order of operations. This allows us to recapture portions of the wavefield not following easily predicted plane wave moveout such as triplicated or diffracted phases leading to a more accurate image.
DE: 7200 SEISMOLOGY
DE: 7203 Body wave propagation
SC: Seismology [S]
MN: 2004 AGU Fall Meeting