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1992 Fiscal Year Final Research Report Summary

Study of the inhomogeneous structure in the subduction zone based on the analysis of seismogram envelopes

Research Project

Project/Area Number 03640359
Research Category

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

Allocation TypeSingle-year Grants
Research Field 固体地球物理学
Research InstitutionTOHOKU UNIVERSITY

Principal Investigator

SATO Haruo  東北大学, 理学部, 助教授 (80225987)

Co-Investigator(Kenkyū-buntansha) MASUDA Tetsu  応用地質株式会社, 技師 (00111245)
Project Period (FY) 1991 – 1992
KeywordsSeismic waves / Internal structure of the Earth / Inhomogeneity / Random structure / Scattering / Attenuation / Lithosphere
Research Abstract

The elastic structure near around the subduction zone shows relatively strong inhomogeneities. Focusing on the decay of seismogram envelopes with increasing travel distance in the randomly inhomogeneous structure, we have constructed mathematical models, and estimated the characteristics of randomness in the wedge mantle beneath Tokai, Kanto, and Tohoku area from the practical analysis.
(1) Envelope analysis: We proposed an inversion method to estimate the attenuation and randomness from the full seismogram envelope. From the evidence that the envelope broadening is larger at the back arc side of the volcanic front compared with those in the fore arc side, we found short wavelength components of the randomness are larger in the back arc side than those in the fore arc side.
(2) Frequency dependent attenuation: From the comparison of the incident and the reflected phases in borehole seismograms, we quantitatively estimated S wave attenuation in the sediment layer. Extending the conventional coda normalization method, we proposed a method for the simultaneous measurement of P and S wave attenuation.
(3) Measurement of the ratio of scattering attenuation and intrinsic absorption: Supposing isotropic scattering we calculated the time trace of S wave energy density based on the Monte-Carlo simulation. Comparing with the simulation and the observed data, we quantitatively estimated the ratio of scattering to intrinsic attenuation in the Kanto-Tokai area.
(4) Mathematical modeling: We have formulated the multiple isotropic scattering model including P-S conversions based on the energy transportation theory.
(5) Field observation: We started field observation at three sites in Tohoku, and found that the envelope shapes clearly depend on their ray paths.

  • Research Products

    (14 results)

All Other

All Publications (14 results)

  • [Publications] F.Scherbaum: "Inversion of full seismogram envelopes based on the parabolic apporoximation:Est:mation of randomness and Q_S^<-1> in southeast Honshu, Japan" J.Geophys.Res. 96. 2223-2232 (1991)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] H.SATO: "Study of seismogram envelopes based on scattering by random inhomogeneities in the lithosphere:Areview" Phys.Earth.Planet.Inter. 67. 4-19 (1991)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] M.Fehler: "Separation of Scattering and intrinsic attenuation for the Kanto-Tokairagion,Japan,using measurements of S-wave energy versus hypocentral distance" Geophys.J.Int.108. 787-800 (1992)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Y.FUKUSHIMA: "Measurement of Q^<-1> for S waves in mudstone at Chikura, Jyapan: Comparison of incident and reflected phases in borehole seismograns" Bull.Seismol Soci.Amev. 82. 148-163 (1992)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] H.SATO: "Energy transportation in one-and two dimensional Scattering media:analytic solutions of the multiple isotropic scattering model" Geophys.J.Int.112. 141-146 (1993)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K.YOSHIMOTO: "Frequency dependent attenuation of P and S waves in the Kanto-area, Japan, based on the coda normalization method" Geophys,J,Int.印刷中. (1993)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] H.SATO (ゲストエディーターとして): "Special Issue on “Scatteving and attenuation of Seismic waves". Phys. Earth Plomet. Inter.Vol.67" Elsevier 出版社, 210 (1991)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Scherbaum, F. and H. Sato: "Inversion of full seismogram envelopes based on the parabolic approximation: Estimation of randomness and Q_S^<-1> southeast Honshu, Japan" J. Geophys. Res.96. 2223-2232 (1991)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Sato, H.,: "Study of seismogram envelopes based on scattering by random inhomogeneities in the lithosphere: A review" Phys. Earth Planet. Inter.67. 4-19 (1991)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Fehler, M., M. Hoshiba, H. Sato, and K. Obara: "Separation of scattering and intrinsic attenuation for the Kanto-Tokai region, Japan, using measurements of S-wave energy versus hypocentral distance" Geophys. J. Int.108. 787-800 (1992)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Fukushima, Y., S. Kinoshita, and H. Sato: "Measurement of Q^<-1> for S waves in mudstone at Chikura, Japan: Comparison of incident and reflected phases in borehole seismograms" Bull. Seismol. Soc. Amer.82. 148-163 (1992)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Sato, H.,: "Energy transportation in one- and two- dimensional scattering media: Analytic solutions of the multiple isotropic scattering model" Geophys. J. Int.112. 141-146 (1993)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Yoshimoto, K., H. Sato and M. Ohtake: "Frequency dependent attenuation of P and S waves in the Kanto area, Japan, based on the coda normalization method" Geophys. J. Int.(1993)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Sato, H.: "(as a Guest Editor), Special issue on "Scattering and attenuation of seismic waves"" Phys. Earth Planet. Inter.67. 1-210 (1991)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1994-03-24  

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