Seismic Traveltime Tomography in Anisotropic Black Shale

이방성 특성이 강한 흑색 셰일에서 탄성파 주시 토모그래피

  • Published : 2007.11.30

Abstract

Seismic traveltime tomography technique was conducted at a site composed of black shale. It is well known that black shale has strong anisotropic property. Therefore, the anisotropic property of black shale has to be considered to obtain the appropriate subsurface velocity model by an inversion process. To estimate the anisotropic constant of the velocity of the black shale in the survey area, the relation between the velocity, which is calculated by the straight ray path and the first arrival time, and the angle of the ray propagation was examined. The elliptically shaped relation was found and it reveals that the black shale contains the anisotropic property of velocity. It was also noticed that the horizontal velocity is faster than the vertical velocity. When the estimated anisotropic constant was applied in the process of the velocity inversion for three sets of field data, we could obtain the appropriate velocity structures of the site that is consistent with the result of the geological survey.

References

  1. 김정호, 조성준, 이명종, 2005, 이방성 레이다 시추공 토모그래피 와 그 응용, 한국물리탐사학회 제7회 특별심포지엄 학술발표 논문집, 한국물리탐사학회, 21-36
  2. 정창호, 2006, 불균질 횡등방성 매질에서의 탄성파 주시토모그 래피, 공학박사학위논문, 서울대학교
  3. Jung, Y., and Kim, J.-H., 1999, Application of anisotropic georadar tomography to monitor rock physical property changes, Journal of Environmental and Engineering Geophysics, 4, 87-92 https://doi.org/10.4133/JEEG4.2.87
  4. Lynn, H. B., 1996, A Geophysicist's view on seismic anisotropy, Seismic Anisotropy, 1-14
  5. Ramamurthy, T., and Arora, V. K., 1993, A classification for intact and jointed rocks, in A. Anagnostoplulos, et al., Ed., Geotechnical Engineering of Hard Soils - Soft Rocks, A.A. Balkema, Rotterdam, 235-242
  6. Vasco, D. W., Peterson, J. E., Jr., and Lee, K. H., 1997, Groundpenetrating radar velocity tomography in heterogeneous and anisotropic media, Geophysics, 62, 1758-1773 https://doi.org/10.1190/1.1444276