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Refraction traveltime tomography using damped monochromatic wavefield

Cited 12 time in Web of Science Cited 16 time in Scopus
Authors
Pyun, Sukjoon; Shin, Changsoo; Min, Dong-Joo; Ha, Taeyoung
Issue Date
2005-03-22
Publisher
Society of Exploration Geophysicists (SEG)
Citation
Geophysics, 70, U1-U7
Keywords
Wavefieldtomographytraveltimedamped monochromatic wavefiled
Abstract
For complicated earth models, wave-equation–based
refraction-traveltime tomography is more accurate than
ray-based tomography but requires more computational
effort. Most of the computational effort in traveltime
tomography comes from computing traveltimes
and their Fr´echet derivatives, which for ray-based
methods can be computed directly. However, in most
wave-equation traveltime-tomography algorithms, the
steepest descent direction of the objective function
is computed by the backprojection algorithm, without
computing a Fr ´echet derivative directly.
We propose a new wave-based refraction-traveltime–
tomography procedure that computes Fr´echet derivatives
directly and efficiently. Our method involves solving
a damped-wave equation using a frequency-domain,
finite-element modeling algorithm at a single frequency
and invoking the reciprocity theorem. A damping factor,
which is commonly used to suppress wraparound
effects in frequency-domain modeling, plays the role
of suppressing multievent wavefields. By limiting the
wavefield to a single first arrival, we are able to extract
the first-arrival traveltime from the phase term
without applying a time window. Computing the partial
derivative of the damped wave-equation solution
using the reciprocity theorem enables us to compute
the Fr ´echet derivative of amplitude, as well as that of
traveltime, with respect to subsurface parameters. Using
the Marmousi-2 model, we demonstrate numerically
that refraction traveltime tomography with large-offset
data can be used to provide the smooth initial velocity
model necessary for prestack depth migration.
ISSN
0016-8033
Language
English
URI
http://hdl.handle.net/10371/6108
DOI
https://doi.org/10.1190/1.1884829
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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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