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Refraction tomography using a waveform-inversion back-propagation technique

Cited 21 time in Web of Science Cited 33 time in Scopus
Authors
Min, Dong-Joo; Shin, Changsoo
Issue Date
2006-05-26
Publisher
Society of Exploration Geophysicists (SEG)
Citation
Geophysics, 71, R21-R30
Keywords
Waveform inversionBackpropagationReflaction tomogragpy
Abstract
One of the applications of refraction-traveltime tomography
is to provide an initial model for waveform inversion and
Kirchhoff prestack migration. For such applications, we need a
refraction-traveltime tomography method that is robust for complicated
and high-velocity-contrast models. Of the many refraction-
traveltime tomography methods available, we believe
wave-based algorithms to be best suited for dealing with complicated
models.
We developed a new wave-based, refraction-tomography algorithm
using a damped wave equation and a waveform-inversion
back-propagation technique. The imaginary part of a complex
angular frequency, which is generally introduced in
frequency-domain wave modeling, acts as a damping factor. By
choosing an optimal damping factor from the numerical-dispersion
relation, we can suppress the wavetrains following the
first arrival. The objective function of our algorithm consists of
residuals between the respective phases of first arrivals in field
data and in forward-modeled data. The model-response, firstarrival
phases can be obtained by taking the natural logarithm
of damped wavefields at a single frequency low enough to yield
unwrapped phases, whereas field-data phases are generated by
multiplying picked first-arrival traveltimes by the same angular
frequency used to compute model-response phases.
To compute the steepest-descent direction, we apply a
waveform-inversion back-propagation algorithm based on the
symmetry of the Green’s function for the wave equation i.e.,
the adjoint state of the wave equation , allowing us to avoid directly
computing and saving sensitivities Fréchet derivatives .
From numerical examples of a block-anomaly model and the
Marmousi-2 model, we confirm that traveltimes computed from
a damped monochromatic wavefield are compatible with those
picked from synthetic data, and our refraction-tomography
method can provide initial models for Kirchhoff prestack depth
migration.
ISSN
0016-8033
Language
English
URI
http://hdl.handle.net/10371/6106
DOI
https://doi.org/10.1190/1.2194522
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College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Energy Systems Engineering (에너지시스템공학부)Journal Papers (저널논문_에너지시스템공학부)
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