Refraction traveltime tomography using damped monochromatic wavefield
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Title
- Refraction traveltime tomography using damped monochromatic wavefield
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Author(s)
- Pyun, S; Shin, C; Min, DJ; Ha, T
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Alternative Author(s)
- 민동주
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Publication Year
- 2005-03
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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 Frechet 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 Frechet derivative directly. We propose a new wave-based refraction-traveltime-tomography procedure that computes Frechet 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-do main 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 Frechet 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.
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ISSN
- 0016-8033
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URI
- https://sciwatch.kiost.ac.kr/handle/2020.kiost/5092
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DOI
- 10.1190/1.1884829
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Bibliographic Citation
- GEOPHYSICS, v.70, no.2, pp.U1 - U7, 2005
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Publisher
- SOC EXPLORATION GEOPHYSICISTS
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Subject
- RAY TOMOGRAPHY; INVERSION; MIGRATION
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Type
- Article
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Language
- English
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Document Type
- Article
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