Geophysics and Geophysical Exploration (지구물리와물리탐사)

Korean Society of Earth and Exploration Geophysicists (한국지구물리·물리탐사학회)
권호 표지

Interactive analysis tools for the wide-angle seismic data for crustal structure study (Technical Report)

지각 구조 연구에서 광각 탄성파 자료를 위한 대화식 분석 방법들

  • Fujie, Gou (Institute for Research on Earth Evolution (IFREE) Japan Agency for Marine-Earth Science and Technology (JAMSTEC)) ;
  • Kasahara, Junzo (Japan Continental Shelf Survey Co. Ltd.) ;
  • Murase, Kei (Kawasaki Geological Engineering Co. Ltd.) ;
  • Mochizuki, Kimihiro (Earthquake Research Institute, University of Tokyo) ;
  • Kaneda, Yoshiyuki (Institute for Research on Earth Evolution (IFREE) Japan Agency for Marine-Earth Science and Technology (JAMSTEC))
  • 등강강 (해양연구개발기구(JAMSTEC), 지구내부변동연구센터(IFREE)) ;
  • 립원순삼 (일본 대륙붕조사 (주)) ;
  • 촌뢰규 (카와사키 지질(주)) ;
  • 망월공광 (동경대학, 지진연구소) ;
  • 김전의행 (해양연구개발기구(JAMSTEC), 지구내부변동연구센터(IFREE))
  • Published : 2008.02.29
Download PDF
⟨ Previous Next ⟩

Abstract

The analysis of wide-angle seismic reflection and refraction data plays an important role in lithospheric-scale crustal structure study. However, it is extremely difficult to develop an appropriate velocity structure model directly from the observed data, and we have to improve the structure model step by step, because the crustal structure analysis is an intrinsically non-linear problem. There are several subjective processes in wide-angle crustal structure modelling, such as phase identification and trial-and-error forward modelling. Because these subjective processes in wide-angle data analysis reduce the uniqueness and credibility of the resultant models, it is important to reduce subjectivity in the analysis procedure. From this point of view, we describe two software tools, PASTEUP and MODELING, to be used for developing crustal structure models. PASTEUP is an interactive application that facilitates the plotting of record sections, analysis of wide-angle seismic data, and picking of phases. PASTEUP is equipped with various filters and analysis functions to enhance signal-to-noise ratio and to help phase identification. MODELING is an interactive application for editing velocity models, and ray-tracing. Synthetic traveltimes computed by the MODELING application can be directly compared with the observed waveforms in the PASTEUP application. This reduces subjectivity in crustal structure modelling because traveltime picking, which is one of the most subjective process in the crustal structure analysis, is not required. MODELING can convert an editable layered structure model into two-way traveltimes which can be compared with time-sections of Multi Channel Seismic (MCS) reflection data. Direct comparison between the structure model of wide-angle data with the reflection data will give the model more credibility. In addition, both PASTEUP and MODELING are efficient tools for handling a large dataset. These software tools help us develop more plausible lithospheric-scale structure models using wide-angle seismic data.

큰 입사각을 가진 탄성파 반사법과 굴절법 자료의 분석은 지각 규모의 구조 연구에서 중요한 역할을 한다. 그러나, 관측된 자료로부터 적합한 속도 구조 모델을 바로 얻는 것은 상당히 어려운 일이며, 지각 구조 분석은 본질적으로 비선형 문제이기 때문에 구조 모델을 단계적으로 향상 시켜야만 한다. 광각 지각 구조 모델링에는 위상식별과 시행착오 전진 모델링과 같은 몇 가지 주관적인 과정들이 있다. 광각 자료 분석에서 이러한 주관적인 과정들은 결과 모델들의 유일성과 신뢰성을 감소시키기 때문에, 분석절차에서 주관성을 감소시키는 것이 중요하다. 이러한 관점에서, 우리는 지각 구조 모델의 개발에 사용될 PASTEUP과 MODELING이라는 2개의 소프트웨어를 설명하고 있다. PASETUP은 기록 단면도의 도시, 광각 탄성파 자료 분석 그리고 위상 피킹을 쉽게 해주는 대화식 응용프로그램이다. PASETUP은 신호대잡음 비를 향상시키고 위상식별을 도와주는 분석 기능과 다양한 필터를 갖추고 있다. MODELLING은 속도모델의 편집과 파선 모델링을 위한 대화식 응용프로그램이다. MODELING에 의해 계산된 주행시간은 PASTEUP에서 관찰된 파형과 바로 비교될 수 있다. 이것은 지각구조 분석에서 가장 주관적인 과정 중 하나인 주행시간 피킹이 필요 없기 때문에 지각 구조 모델링에서 주관성을 감소시킨다. MODELING은 편집 가능한 층서구조 모델을 다중 채널 탄성파(MCS) 반사파 자료의 시간 단면도와 비교할 수 있는 왕복 주시로 변환할 수 있다. 반사파 자료와 광각 자료의 구조 모델 사이의 직접 비교는 모델에 좀 더 신뢰성을 부여한다. 게다가 PASTEUP과 MODELING 둘다 큰 자료를 다루기에 효과적인 도구이다. 이 소프트웨어들은 광각 탄성파 자료를 이용한 좀 더 그럴듯한 지각-규모의 구조 모델을 개발하는데 도움을 준다.

Keywords

References

  1. Cerveney, V., Molotkov, I. A., and Psencik, I., 1977, Ray method in seismology: Praha, Univ. Karlova
  2. Cohen, J. K., and Stockwell, J. J.W., 2007, CWP/SU: Seismic Un*x, Release No. 40: an open source software package for seismic research and processing: Center for Wave Phenomena, Colorado School of Mines
  3. Fujie, G., Ito, A., Kodaira, S., Takahashi, N., and Kaneda, Y., 2006, Confirming sharp bending of the pacific plate in the northern japan trench subduction zone by applying a traveltime mapping method: Physics of the Earth and Planetary Interiors 157, 72-85. doi: 10.1016/j.pepi.2006.03.013
  4. Fujie, G., Kasahara, J., Sato, T., and Mochizuki, K., 2000, Traveltime and raypath computation: a new method in a heterogeneous medium: Geophysical Exploration 53, 1-11
  5. Fujie, G., Mochizuki, K., and Kasahara, J., 2003, Newtraveltime and raypath computation methods for reflection and ps-converted waves using a regular-grid: Geophysical Exploration 56, 357-368
  6. Hayakawa, T., Kasahara, J., Hino, R., Sato, T., Shinohara, M., Kamimura, A., Nishino, M., Sato, T., and Kanazawa, T., 2002, Heterogeneous structure across the source regions of the 1968 Tokachi-Oki and the 1994 Sanriku- Haruka-Oki earthquakes at the Japan Trench revealed by an ocean bottom seismic survey: Physics of the Earth and Planetary Interiors 132, 89-104. doi: 10.1016/S0031-9201(02)00046-8
  7. Hole, J. A., and Zelt, B. C., 1995, 3-D finite-difference reflection traveltimes: Geophysical Journal International 121, 427-434. doi: 10.1111/j.1365- 246X.1995.tb05723.x
  8. Ito, A., Fujie, G., Miura, S., Kodaira, S., Kaneda, Y., and Hino, R., 2005, Bending of the subducting oceanic plate and its implication for rupture propagation of large interplate earthquakes off Miyagi, Japan, in the Japan trench subduction zone: Geophysical Research Letters 32, L05310. doi: 10.1029/2004GL022307
  9. Ito, A., Fujie, G., Tsuru, T., Kodaira, S., Nakanishi, A., and Kaneda, Y. 2004, Fault plane geometry in the source region of the 1994 Sanrikuoki earthquake: Earth and Planetary Science Letters 223, 163-175. doi: 10.1016/j.epsl.2004.04.007
  10. Kasahara, J., Kubota, R., Tanaka, T., Mizohata, S., Nishiyama, E., Nishizawa, A., and Kaneda, K., 2007, Newprecise method for the crustal structure analysis using OBS and control sources, Abstract of 2007 JGU, 0135-007
  11. Kodaira, S., Hori, T., Ito, A., Miura, S., Fujie, G., Park, J.-O., Baba, T., Sakaguchi, H., and Kaneda, Y., 2006, A cause of rupture segmentation and synchronization in the nankai trough revealed by seismic imaging and numerical simulation: Journal of Geophysical Research 111, B08301. doi: 10.1029/2005JB004030
  12. Kodaira, S., Sato, T., Takahashi, N., Ito, A., Tamura, Y., Tatsumi, Y., and Kaneda, Y., 2007, Seismological evidence for variable growth of crust along the Izu intraoceanic arc: Journal of Geophysical Research 112, B05104. doi: 10.1029/2006JB004593
  13. Kubota, R., Nishiyama, E., Murase, K., and Kasahara, J., 2005, Fast computation algorithm of raypaths and thies travel times including later arrivals for a multi layered earth model: Proc. of "International Symposium on Marine Geosciences - New Observation Data and Interpretation", 109-112
  14. Larsen, S., 2000, "E3D" 2D/3D elastic finite difference wave propagation code, UCRL. (http://www.seismo.unr.edu/ftp/louie/class/455/e3d/)
  15. Letgert, J. H., 1988, User's manual for ray84/r83plt - interactive twodimensional raytracing/synthetic seismogram package: U. S. Geological Survey Open-File report, 238
  16. Loss, J., Pecher, I., and ten Brink, U., 1998, RayGUI - a graphical 2-d raytracing package for unix: U. S. Geological Survey Open-File report, 98-203
  17. Miura, S., Tsuru, T., Fujie, G., Nakajima, Y., and Asakawa, E., 2006, Study on a practical application of OBS/MCS integrated imaging: Geophysical Exploration 59, 485-495
  18. Operto, S., Virieux, J., Dessa, J. X., and Pascal, G., 2006, Crustal seismic imaging from multifold ocean bottom seismometer data by frequency domain full waveform tomography: application to the eastern Nankai trough: Journal of Geophysical Research 111, B09306. doi: 10.1029/2005JB003835
  19. Pratt, R. G., 1999, Seismic waveform inversion in the frequency domain, part 1: Theory and verification in a physical scale model: Geophysics 64, 888-901. doi: 10.1190/1.1444597
  20. Sambridge, M., and Gallagher, K., 1993, Earthquake hypocenter location using genetic algorithm: Bulletin of Seismology Society of America 83, 1467-1491
  21. Song, J., and ten Brink, U., 2005, RayGUI 2.0 - a graphical user interface for interactive forward and inversion ray-tracing:U. S. Geological Survey Open-File report, 1426
  22. Stoffa, P., Buhl, P., Diebold, J., and Wenzel, F., 1981, Direct mapping of seismic data to the domain of intercept time and ray-parameter - a planewave decomposition: Geophysics 46, 255-267. doi: 10.1190/1.1441197
  23. Tarantora, A., 1987, Inverse Problem Theory: Methods for data fitting and model parameter estimation, Amsterdam, Elsevier
  24. Vidale, J., 1988, Finite-difference calculation of travel times: Bulletin of the Seismological Society of America 78, 2062-2076
  25. Wessel, P., and Smith, W. H. F., 1998, New, improved version of generic mapping tools released: EOS Transactions 79, 579. doi: 10.1029/98EO00426
  26. Zelt, B. C., Talwani, M., and Zelt, C. A., 1998, Prestack depth migration of dense wide-angle seismic data: Tectonophysics 286, 193-208. doi: 10.1016/S0040-1951(97)00265-5
  27. Zelt, C. A., 1999, Modelling strategies and model assessment for wideangle seismic traveltime data: Geophysical Journal International 139, 183-204. doi: 10.1046/j.1365-246X.1999.00934.x
  28. Zelt, C. A., Sain, K., Naumenko, J. V., and Sawyer, D. S., 2003, Assessment of crustal velocity models using seismic refraction and reflection tomography: Geophysical Journal International 153, 609-626. doi: 10.1046/j.1365-246X.2003.01919.x
  29. Zelt, C. A., and Smith, R. B., 1992, Seismic traveltime inversion for 2-D crustal velocity structure: Geophysical Journal International 108, 16-34. doi: 10.1111/j.1365-246X.1992.tb00836.x
  30. Zhang, J., Brink, U. S., and Toks¨oz, M. N., 1998, Nonlinear refraction and reflection travel time tomography: Journal of Geophysical Research 103, 29743-28757. doi: 10.1029/98JB01981