Refraction tomography using a waveform-inversion back-propagation technique SCIE SCOPUS

Cited 24 time in WEB OF SCIENCE Cited 39 time in Scopus
Title
Refraction tomography using a waveform-inversion back-propagation technique
Author(s)
Min, Dong-Joo; Shin, Changsoo
Publication Year
2006-05
Abstract
One of the applications of refraction-travel time 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 alorithm 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, first-arrival 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 (Frechet 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
URI
https://sciwatch.kiost.ac.kr/handle/2020.kiost/4887
DOI
10.1190/1.2194522
Bibliographic Citation
GEOPHYSICS, v.71, no.3, pp.R21 - R30, 2006
Publisher
SOC EXPLORATION GEOPHYSICISTS
Subject
TRAVEL-TIME TOMOGRAPHY; FINITE-DIFFERENCE; WEATHERING LAYER; FREQUENCY-SPACE; RAY TOMOGRAPHY; MIGRATION; SCALAR
Keywords
Seismic waves; Seismology; Wave equations
Type
Article
Language
English
Document Type
Article
Publisher
SOC EXPLORATION GEOPHYSICISTS
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