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A test of ray theory and scattering theory based on a laboratory experiment using ultrasonic waves and numerical simulation by finite-difference method

2002; Oxford University Press; Volume: 148; Issue: 2 Linguagem: Inglês

10.1046/j.1365-246x.2002.01001.x

1365-246X

Jesper Spetzler, Chadaram Sivaji, Osamu Nishizawa, Y. Fukushima,

Geophysical Methods and Applications

Geophysical Journal InternationalVolume 148, Issue 2 p. 165-178 A test of ray theory and scattering theory based on a laboratory experiment using ultrasonic waves and numerical simulation by finite-difference method Jesper Spetzler, Corresponding Author Jesper Spetzler Department of Geophysics, Utrecht University, P.O. Box 80.021, NL-3508 The Netherlands. E-mail: j.spetzler@citg.tudelft.nl *Now at: Dept. of Applied Earth Sciences, TU Delft, Mijnbouwstraat 120, NL-2628 RZ Delft, The Netherlands †Now at: Ministry of Science and Technology, Govt. of India, New Mehrauli Road, New Delhi 110 016, India ‡Now at: CTBTO Data Centre, International Centre P.O. Box 1200, A-1400 Vienna, AustriaSearch for more papers by this authorChadaram Sivaji, Corresponding Author Chadaram Sivaji Geophysics, Department, Geological Survey of Japan Higashi 1-1-3, Tsukuba, Ibaraki 305-8567, Japan *Now at: Dept. of Applied Earth Sciences, TU Delft, Mijnbouwstraat 120, NL-2628 RZ Delft, The Netherlands †Now at: Ministry of Science and Technology, Govt. of India, New Mehrauli Road, New Delhi 110 016, India ‡Now at: CTBTO Data Centre, International Centre P.O. Box 1200, A-1400 Vienna, AustriaSearch for more papers by this authorOsamu Nishizawa, Osamu Nishizawa Geophysics, Department, Geological Survey of Japan Higashi 1-1-3, Tsukuba, Ibaraki 305-8567, JapanSearch for more papers by this authorYo Fukushima, Corresponding Author Yo Fukushima Graduate School of Science, Tohoku University, Aramaki-Aza Aoba, Aoba-ku, Sendai 980-8578, Japan *Now at: Dept. of Applied Earth Sciences, TU Delft, Mijnbouwstraat 120, NL-2628 RZ Delft, The Netherlands †Now at: Ministry of Science and Technology, Govt. of India, New Mehrauli Road, New Delhi 110 016, India ‡Now at: CTBTO Data Centre, International Centre P.O. Box 1200, A-1400 Vienna, AustriaSearch for more papers by this author Jesper Spetzler, Corresponding Author Jesper Spetzler Department of Geophysics, Utrecht University, P.O. Box 80.021, NL-3508 The Netherlands. E-mail: j.spetzler@citg.tudelft.nl *Now at: Dept. of Applied Earth Sciences, TU Delft, Mijnbouwstraat 120, NL-2628 RZ Delft, The Netherlands †Now at: Ministry of Science and Technology, Govt. of India, New Mehrauli Road, New Delhi 110 016, India ‡Now at: CTBTO Data Centre, International Centre P.O. Box 1200, A-1400 Vienna, AustriaSearch for more papers by this authorChadaram Sivaji, Corresponding Author Chadaram Sivaji Geophysics, Department, Geological Survey of Japan Higashi 1-1-3, Tsukuba, Ibaraki 305-8567, Japan *Now at: Dept. of Applied Earth Sciences, TU Delft, Mijnbouwstraat 120, NL-2628 RZ Delft, The Netherlands †Now at: Ministry of Science and Technology, Govt. of India, New Mehrauli Road, New Delhi 110 016, India ‡Now at: CTBTO Data Centre, International Centre P.O. Box 1200, A-1400 Vienna, AustriaSearch for more papers by this authorOsamu Nishizawa, Osamu Nishizawa Geophysics, Department, Geological Survey of Japan Higashi 1-1-3, Tsukuba, Ibaraki 305-8567, JapanSearch for more papers by this authorYo Fukushima, Corresponding Author Yo Fukushima Graduate School of Science, Tohoku University, Aramaki-Aza Aoba, Aoba-ku, Sendai 980-8578, Japan *Now at: Dept. of Applied Earth Sciences, TU Delft, Mijnbouwstraat 120, NL-2628 RZ Delft, The Netherlands †Now at: Ministry of Science and Technology, Govt. of India, New Mehrauli Road, New Delhi 110 016, India ‡Now at: CTBTO Data Centre, International Centre P.O. Box 1200, A-1400 Vienna, AustriaSearch for more papers by this author First published: 28 June 2008 https://doi.org/10.1046/j.1365-246X.2002.01001.xCitations: 6AboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat SUMMARY The structure of the Earth is represented by a wide spectrum of small- and large-scale structures. However, tomographic imaging techniques based on ray theory are often applied inappropriately in models with a characteristic length of heterogeneity smaller than the wavelength and width of the Fresnel zone. In other words, the conditions for ray theory are not satisfied in such models. It is therefore necessary to apply the diffraction theory of waves in tomographic reconstruction techniques in order to retrieve images of the Earth with a more general theory for wave propagation than ray theory. Physically speaking, scattering theory takes the finite-frequency effect of waves into account. We performed a test of ray theory and scattering theory in an ultrasonic wave experiment and in a numerical finite-difference experiment using random media with correlation lengths smaller than the width of the Fresnel zone. We used a stochastic approach to compute the mean squared value of time-shift variations calculated from ray theory and diffraction theory. The theoretical results were compared with the experimental values obtained in the laboratory experiment using rock samples with different length-scales of heterogeneity and from numerical experiments on wave propagation in quasi-random media. We observed that ray theory systematically overestimates the mean squared value of time-shift variations, while the observed statistical values from the laboratory experiments are well predicted by scattering theory. This means that tomographic imaging techniques based on ray theory suffer from a loss of resolution when the reconstructing models have a characteristic length of heterogeneity smaller than the width of the Fresnel zone. Citing Literature Volume148, Issue2February 2002Pages 165-178 RelatedInformation