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Study of Earth's inner core using synthetic seismograms calculated by Spectral-Element method

Research Project

Project/Area Number 16204035
Research Category

Grant-in-Aid for Scientific Research (A)

Allocation TypeSingle-year Grants
Section一般
Research Field Solid earth and planetary physics
Research InstitutionIndependent Administrative Institution, Japan Agency for Marine-Earth Science and Technology

Principal Investigator

TSUBOI Seiji  Independent Administrative Institution, Japan Agency for Marine-Earth Science and Technology, Institute for Research on Earth Evolution, Program director, 地球内部変動研究センター, プログラムディレクター (90183871)

Co-Investigator(Kenkyū-buntansha) TONO Yoko  Independent Administrative Institution, Japan Agency for Marine-Earth Science and Technology, Institute for Research on Earth Evolution, Researcher, 地球内部変動研究センター, 研究員 (90359183)
Project Period (FY) 2004 – 2006
Project Status Completed (Fiscal Year 2006)
Budget Amount *help
¥47,970,000 (Direct Cost: ¥36,900,000、Indirect Cost: ¥11,070,000)
Fiscal Year 2006: ¥3,120,000 (Direct Cost: ¥2,400,000、Indirect Cost: ¥720,000)
Fiscal Year 2005: ¥6,630,000 (Direct Cost: ¥5,100,000、Indirect Cost: ¥1,530,000)
Fiscal Year 2004: ¥38,220,000 (Direct Cost: ¥29,400,000、Indirect Cost: ¥8,820,000)
KeywordsEarth's core / Earth's internal structure / Broadband seismograms / Synthetic seismograms / Earth Simulator / Spectral-Element method / Large scale numerical simulation
Research Abstract

We use broadband seismograms recorded at an antipodal station, where the epicentral distance is more than 179 degrees, and show that the amplitude of a PKIIKP phase (single reflection within the inner core at the inner core boundary) can be modeled by the existence of thin (20km) slow P-wave velocity (-10% at the inner core boundary from PREM) layer at the bottom of the outer core. We calculate theoretical seismograms for fully three dimensional Earth model using the Spectral-Element method on the Earth Simulator. We found that the current Earth model cannot reproduce the amplitude of PKIIKP phase. Because the amplitude of PKIIKP phase is sensitive to seismological impedance (product of the density and the seismic wave velocity) contrast at the inner core boundary, it is suggested that the reduction of P-wave velocity within this layer should not accompany a reduction of density.
We also have calculated synthetic seismograms with aisotropic inner core model for several earthquakes and compared with the synthetics which are calculated for isotropic inner core model. Preliminary comparison shows that the travel time differences between anisotropic inner core model and isotropic core model for PKPab phases are at most a few seconds. There seems to be no significant differences in waveforms of PKP phases. These differences in travel times may help us to improve inner core fine structure by comparing these synthetics with observation.
At present we could calculate synthetic seismograms that are accurate up to 3.5 sec by using the 507 nodes (4056 CPUs) of the Earth Simulator. It is desirable so that we can calculate up to 1 sec accuracy, which represents dominant period of body wave. We could estimate that we need at least 16 times larger machine than the current Earth Simulator to realize computation of synthetics which have 1 sec accuracy.

Report

(4 results)
  • 2006 Annual Research Report   Final Research Report Summary
  • 2005 Annual Research Report
  • 2004 Annual Research Report
  • Research Products

    (20 results)

All 2006 2005 2004

All Journal Article (19 results) Book (1 results)

  • [Journal Article] Synthetic Seismograms for Realistic 3D Earth Model with Anisotropic Inner Core2006

    • Author(s)
      Tsuboi, S., Tono, Y.
    • Journal Title

      EOS Trans.AGU 87

    • Related Report
      2006 Annual Research Report
  • [Journal Article] Mapping the 410- and 660-km discontinuities beneath the Japanese Islands2005

    • Author(s)
      Y.Tono
    • Journal Title

      J. Geophys. Res 110

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] The spectral-element in seismology2005

    • Author(s)
      D.Komatitsch
    • Journal Title

      Geophys. Monograph 157

      Pages: 205-227

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Rayleigh-wave multipathing along the west coast of North America2005

    • Author(s)
      C.Ji
    • Journal Title

      Bull. Seismo. Soc. America 95

      Pages: 2125-2135

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Earth Simulator2005

    • Author(s)
      S.Tsuboi
    • Journal Title

      2005 Yearbook of Science and Technology

      Pages: 86-89

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Earth Simulator2005

    • Author(s)
      Tsuboi, S.
    • Journal Title

      2005 Yearbook of Science and Technology, McGraw-Hill

      Pages: 86-89

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Mapping the 410- and 660-km discontinuities beneath the Japanese Islands2005

    • Author(s)
      Tono, Y., T.Kunugi, Y.Fukao, S.Tsuboi, K., Kanjo, K.Kasahara
    • Journal Title

      J.Geophys.Res. vol.110

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] The spectral-element in seismology, in Seismic Earth : Array analysis of broadband seismograms2005

    • Author(s)
      Komatitsch, D., Tsuboi, S., Tromp, J.
    • Journal Title

      Geophys.Monograph 157,AUG

      Pages: 205-227

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Rayleigh-wave multipathing along the west coast of North America2005

    • Author(s)
      Ji, C., Tsuboi, S., Komatitsch, D., Tromp, J.
    • Journal Title

      Bull.Seismo.Soc.America 95

      Pages: 2125-2135

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Broadband modeling of global seismic wave propagation on the Earth Simulator using the Spectral-Element Method2005

    • Author(s)
      Tsuboi, S., Komatitsch, D, Ji, C., Tromp, J.
    • Journal Title

      J.Seismological Society of Japan 2,57

      Pages: 321-329

    • NAID

      40006993247

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Rayleigh-wave multipathing along the west coast of North America2005

    • Author(s)
      Ji, C.
    • Journal Title

      Bull. Seismo. Soc. America 95

      Pages: 2125-2135

    • Related Report
      2005 Annual Research Report
  • [Journal Article] The spectral-element in Seismology2005

    • Author(s)
      Komatitsch, D.
    • Journal Title

      Geophysical Monograph 157

      Pages: 205-227

    • Related Report
      2005 Annual Research Report
  • [Journal Article] Mapping the 410- and 660-km discontinuities beneath the Japanese Islands2005

    • Author(s)
      Tono, Y.
    • Journal Title

      J.Geophys.Res. 110

    • Related Report
      2005 Annual Research Report
  • [Journal Article] 地球シミュレータによるスペクトル要素法を用いた全球広帯域理論地震波形計算2005

    • Author(s)
      坪井誠司
    • Journal Title

      地震第2輯 57

      Pages: 321-329

    • Related Report
      2004 Annual Research Report
  • [Journal Article] Mapping of the 410-and 660-km discontinuities beneath the Japanese Islands2005

    • Author(s)
      Tono, Y.
    • Journal Title

      J.Geophys.Res. 印刷中

    • Related Report
      2004 Annual Research Report
  • [Journal Article] Modeling of global seismic wave propagation on the Earth Simulator2004

    • Author(s)
      S.Tsuboi
    • Journal Title

      Journal of the Earth Simulator 1

      Pages: 57-66

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] 地球シミュレータによるスペクトル要素法を用いた 全球広帯域理論地震波伝播計算2004

    • Author(s)
      坪井誠司
    • Journal Title

      地震2 57

      Pages: 321-329

    • NAID

      40006993247

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Modeling of global seismic wave propagation on the Earth Simulator2004

    • Author(s)
      Tsuboi, S., Komatitsch, D, Ji, C., Tromp, J.
    • Journal Title

      Journal of the Earth Simulator 1

      Pages: 57-66

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Modeling of global seismic wave propagation on the Earth Simulator2004

    • Author(s)
      Tsuboi, S.
    • Journal Title

      J.Earth Simulator 1

      Pages: 57-66

    • Related Report
      2004 Annual Research Report
  • [Book] McGraw-Hill Yearbool of Science & Technology 20052005

    • Author(s)
      Tsuboi, S.
    • Publisher
      Earth Simulator
    • Related Report
      2004 Annual Research Report

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Published: 2004-04-01   Modified: 2016-04-21  

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