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Seismic tomography for an azimuthally anisotropic oceanic upper mantle

Research Project

Project/Area Number 63540298
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field 固体地球物理学
Research InstitutionUniversity of Toyama

Principal Investigator

KAWASAKI Ichiro  Toyama Univ., Earth Sci., Assoc. Prof., 理学部, 助教授 (60115136)

Co-Investigator(Kenkyū-buntansha) MATSUMURA Isamu  Kanazawa Univ. of Economics, Lecturer, 経済学部, 講師 (70173862)
Project Period (FY) 1988 – 1990
Project Status Completed (Fiscal Year 1991)
Budget Amount *help
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1990: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1989: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1988: ¥1,000,000 (Direct Cost: ¥1,000,000)
KeywordsSurface waves / Dispersion curve / Rayleigh-Love wave coupling / Pacific ocean / Upper mantle / Low velocity zone / Tomography / Azimuthal anisotropy / 位相速度 / 海洋マントル / 2点法 / トモグラフィ / レ-リ-・ラブカップリング / 表面波 / 異方性
Research Abstract

Azimuthal anisotropy of seismic wave propagation velocity in the oceanic mantle has been supposed to be a fossil tracer of paleo-plate spreading direction and an indication of mechansim of the upper mantle low velocity zone (Kawasaki et al., 1989). We have taken following steps to investigate this issue by an analysis of seismic surface waves.
We have rewritten the equations of motion and Hookean low of an elastic body in an orthogonal curvilinear coordinates. With this representation, we have become to be able to obtain eigenvalues (phase velocities) of surface waves in an azimuthally anisotropic medium by conventional integration method (called y-method in seismology). Based on this new method, we have first demonstrated how Rayleigh-Love wave coupling takes place on the GDSN degital long period seismic records of surface waves propagating in the eastern Pacific ocean due to the anisotropy. This seems to be the first direct observation of seismic nature of upper mantle anisotropy.
Sakai and Kawasaki (1990) investigated how seismic anisotropy effect travel times and amplitudes of body waves and how surface wave velocities are related with those of body waves propagating in an anisotropic media. Yoshida and Kawasaki (1991) checked the trade-off relation between seismic wave velocity and density in the surface wave inversions. They suggested a possibility that density in the middle part of the low velocity zone around 100 km depth could be larger than that of oceanic plate.
In Kawasaki et al. (1989) and Kawasaki (1991), we presented our results excluding theoretical part of this research project on wave propagation and discussed future perspectives along the line of this study.

Report

(4 results)
  • 1991 Final Research Report Summary
  • 1990 Annual Research Report
  • 1989 Annual Research Report
  • 1988 Annual Research Report
  • Research Products

    (23 results)

All Other

All Publications (23 results)

  • [Publications] 川崎 一朗: "地震波速度異方性からみた海洋プレ-トと低速度層" 火山. 33. 185-201 (1988)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] Kawasaki,I.: "An anisotropic image of the oceanic upper mantle" Physics of Earth and Planetary Interiors. 51. 128-129 (1988)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] 川崎 一朗: "低速度構造の地域性とその成因" 地震. 42. 239-254 (1989)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] Tajima,F.: "3D particle motion trajectries:Direct observation of Love-Rayleigh coupling" Geophysical Research Letters. 16. 1051-1054 (1989)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] Kawasaki I.: "Rayleigh-Love wave coupling in an azimuthally anisotropic medium" Journal of Physics of the Earth. 38. 361-390 (1990)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] Sakai,Y.: "Analytic waveforms for a line source in a transversely isotropic medium" Journal of Geophysical Research. 95. 11333-11344 (1990)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] 吉田 満: "レイリ-波分散から推定される西太平洋上部マントルの密度構造" 地震. 44. 53-57 (1991)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] 川崎 一朗: "海と陸のアセノスフェア" 月刊地球. 13. 388-396 (1991)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] Kawasaki, I.: "Oceanic plate and LVZ structure as viewed from large scale seismic anisotropy." Kazan. 33. 185-201 (1988)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] Kawasaki, I.: "An anisotropic image of the oceanic upper mantle." Phys. Earth Planet. Interiors. 51. 128-129 (1988)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] Tajima, F.: "3D particle motion trajectries : Direct fobservation of Love-Rayleigh coupling." Geophy. Res. Lett.,. 16. 1051-1054 (1989)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] Kawasaki, I.: "Regional variation and origin of upper mantle low velocity zone." Zisin 2. 42. 239-254 (1989)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] Kawasaki, I.: "Rayleigh-Love wave coupling in an azimuthally anisotropic medium." J. Phys. Earth. 38. 361-390 (1990)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] Sakai, Y.: "Analytic waveforms for a line source in a transversely isotropic medium." J. Geophy. Res.95, B6, 11. 333-11 (1990)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] Yoshida, M.: "A density profile of the upper mantle in the western Pacific as inferred from Rayleigh wave dispersion." Zisin 2. 44. 53-57 (1991)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] Kawasaki, I.: "Asthenosphere under the ocean and the continent." Gekkan-Chikyu. 13. 388-396 (1991)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] Kawasaki,I.: "RayleighーLove wave coupling in an azimuthally anisotropic medium" Journal of Physics of the Earth. 38. (1990)

    • Related Report
      1990 Annual Research Report
  • [Publications] Sakai,Y.: "Analytic waveforms for a line source in a transversely isotropic medium" Journal of Geophysical Research. 95. 11333-11344 (1990)

    • Related Report
      1990 Annual Research Report
  • [Publications] Tajima,F.and I.Kawasaki: "3D particle motion trajectries:Direct observation of Love-Rayleigh coupling" Geophysical Research Letters. 16. 1051-1054 (1989)

    • Related Report
      1989 Annual Research Report
  • [Publications] Kawasaki,I.: "Seismic anisotropy in the Earth" The Encyclopedia of Solid Earth Geophysics. 994-1005 (1989)

    • Related Report
      1989 Annual Research Report
  • [Publications] 川崎一朗・唐戸俊一郎・大内徹: "低速度構造の地域性とその成因" 地震. 42. 239-254 (1989)

    • Related Report
      1989 Annual Research Report
  • [Publications] 川崎一朗: 火山. 33. 185-201 (1988)

    • Related Report
      1988 Annual Research Report
  • [Publications] I.Kawasaki: Journal of Geophysical Research. (1989)

    • Related Report
      1988 Annual Research Report

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Published: 1988-04-01   Modified: 2016-04-21  

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