Effects of Surface Scattering in Waveform Inversion
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bleibinhaus_2008_final.pdf
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5.6 MB
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Adobe PDF
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ebf95911c1dd538173a43b021a5a2e38
Author(s)
Bleibinhaus, Florian
Rondenay, Stephane
Date Issued
2008
Publisher
Massachusetts Institute of Technology. Earth Resources Laboratory
Series/Report no.
Earth Resources Laboratory Industry Consortia Annual Report;2008-03
Abstract
In full waveform inversion of seismic body waves, the free surface is often ignored on
grounds of computational efficiency. We investigate the effect of this simplification
for highly irregular topography by means of a synthetic example. Our test model and
data conform to a long-offset survey of the upper crust in terms of size and frequency.
Random fractal variations are superimposed on a background model. We compute
synthetic data for this model and different topographies, and we invert it neglecting
the free surface. The resulting waveform models are relatively similar and, for the
most part, show a high degree of correlation with the true model. The inversion of the
irregular-topography data produces a few strong artifacts at shallow depths, but only a
minor decrease in overall resolution. However, both waveform models fail to image
below a strong shallow velocity contrast. The results suggest that in this part of the
model the incapacity to properly reproduce the reverberations from that contrast
without free surface derails both inversions.
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