A Numerical Study on the Effect of Near Surface Inhomogeneity on Rayleigh Wave Propagation and Dispersion

천부 불균질대에 의한 레일리파 전파 및 분산특성 고찰

  • Lee, Sang-Min (Dept. of Geoenvironmental System Engineering, Hanyang University) ;
  • Park, Kwon-Gyu (Korea Institute of Geoscience and Mineral Resources) ;
  • Byun, Joong-Moo (Dept. of Geoenvironmental System Engineering, Hanyang University)
  • 이상민 (한양대학교 지구환경시스템공학과) ;
  • 박권규 (한국지질자원연구원) ;
  • 변중무 (한양대학교 지구환경시스템공학과)
  • Published : 2006.05.31

Abstract

The effect of small-scale near surface inhomogeneity on Rayleigh wave propagation and dispersion has been investigated in this study using two-dimensional FEM elastic modeling. Various inhomogeneity models with a variety of geometrical shape and embedment depth which exist in homogeneous half-space and two-layered media are considered. Results show that any near surface inhomogeneity greater than one wavelength in terms of minimum wavelength of Rayleigh wave shows dispersion characteristics. Such dispersion effect become stronger as the dimensions of the inhomogeneity increase. The effect of horizontal dimension is more dominant factor governing the dispersion characteristics than vertical dimension. However, the dispersion effect can not be identifiable in seismogram if the horizontal dimension is not wide enough. Nonetheless, even in this case, the existence of inhomogeneity can be inferred by the reflection or transmission event of Rayleigh wave. The results can be expected to provide insights on the behavior of Rayleigh wave which may be helpful for designating field work or new processing scheme to detect near surface inhomogeneity by surface wave method.

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