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Seismic exploration of the deep structure beneath the westsern Pacific

Research Project

Project/Area Number 05402015
Research Category

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

Allocation TypeSingle-year Grants
Research Field 固体地球物理学
Research InstitutionThe University of Tokyo

Principal Investigator

FUKAO Yoshio  Univ.Tokyo, Earthq.Res.Inst.Professor, 地震研究所, 教授 (10022708)

Co-Investigator(Kenkyū-buntansha) GELLER Robert  Fuculty of Science, University of Tokyo, Associate Professor, 大学院・理学系研究科, 助教授 (40170154)
YAMADA Isao  School of Science, Nsgoya University, Associate Professor, 理学部, 助教授 (60022670)
TAKEO Minoru  Univ.Tokyo, Earthq.Res.Inst., Associate Professor, 地震研究所, 助教授 (00197279)
SHIMAZAKI Kunihiko  Univ.Tokyo, Earthq.Res.Inst.Professor, 地震研究所, 教授 (50012951)
Project Period (FY) 1993 – 1995
Project Status Completed (Fiscal Year 1997)
Budget Amount *help
¥22,900,000 (Direct Cost: ¥22,900,000)
Fiscal Year 1995: ¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 1994: ¥7,100,000 (Direct Cost: ¥7,100,000)
Fiscal Year 1993: ¥12,000,000 (Direct Cost: ¥12,000,000)
Keywordsbroadband seismometer / tomography / mantle / core-mantle / westsern Pacific / グローバル地震学 / マントル構造 / 海洋プレート / ポセイドン計画 / 地震波速度 / 地球構造 / 背弧海盆
Research Abstract

Seismic exploration of the deep structure beneath the western Pacific
This project aimed at revealing the structure of the deep mantle beneath the western Pacific, the largest subduction zone over the globe.To achieve this goal, we planned(1)to install a broadband station at kamehckoe(kamchatka), (2)to version up the Ponape station, Micronesia, and(3)tomake a tomographic study to obtain a seismic image of the mantle beneath the wastern Pacific.Following is a brief report on the results of our research project.
(1)Installation of a broadband station at Kamehckoe
In 1993 we made various preparation for the installation of a seismic station, including the acquiement and set up of the equipments, negotiation with Russian researchers, and the construction of a vault by them. In 1994 we set up the broadband instruments inside the vault and the operation started for the two components of the instruments.In 1995 the seismometer of the remaining component started in operation. Now all the three co … More mponent seismometers are operated in normal condition.
(2)Version up of the observation system at Ponape
In 1993 the installation of a broadband station was completed at Ponape by a different fund.In 1994 the observation system was up-dated thanks to the replacent of telephone lines with optical cables throughout the island.In 1995 the data transmission system was improved.On the whole, we were able to obtain the data with a good quality throughout the project period.
(3)Seismic tomographic study of the Earth's interior
Whole mantle P wave tomography(1993) : We made a whole mantle P wave tomography by increasing the data as 5 times as large as those used in Fukao et al.(1992)and obtained a sharper image of the stagnant slabs in the mantle transition zone.We also measured the travel time differences between P and PP waves by a waveform correlation method on broadband seismograms.Travel time differences were found to be consistent with the tomographic model where the resolution in the model is good.
measurement of group velocities of surface waves(1994) : We used the newly obtained broadband data at Ponape and Titi-jima to measure the group velocities of Rayleigh waves.We found that in terms of group velocity the oldest ocean floor(160 Ma)between Mariana and Ponape is fastest and the youngest ocean floor between Mariana and Titi-jima is slowest among the sea floors of the Pacific Ocean.
PcP travel time tomography for the core/mantle boundary(1995) : We obtained a laterally heterogeneous structure in the vicinity of the core/mantle boundary(CMB) by a tomographic inversion of P and PcP travel time data. We focused on extracting the significant features of the CMB rather than presenting a new model.We found the low-velocity anomalies beneath southeastern Asia and the high-velocity anomaly under the Arctic region. Less

Report

(4 results)
  • 1997 Final Research Report Summary
  • 1995 Annual Research Report
  • 1994 Annual Research Report
  • 1993 Annual Research Report
  • Research Products

    (29 results)

All Other

All Publications (29 results)

  • [Publications] 大林政行、 桜井太郎、 深尾良夫: "走時インバーションによるマントル3次元構造" 地学雑誌. 104,7. 934-940 (1995)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Obayashi,M. and Y.Fukao: "P and PcP travel time tomography for the core-mantle boundary" J.Geophys.Res.102. 17825-17841 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Fukao,Y.: "Single-force representation of earthquakes due t landslides or the collapse of caverns" Geophys.J.Int.122. 243-248 (1995)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Sugioka,H.,Y.Fukao et al.: "Anomalously Early First Arrivals to the J-array fro Teleseismic Evnets" J.Phys.Earth. 44. 687-699 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] 近藤恵子、 山田功夫: "GPS受信器を利用した刻時装置" 地震. 2,48. 429-431 (1995)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Geller,R.J.and N.Takeuchi: "A new method for computing highly accurate DSM synthetic seismograms" Geophys.J.Int.123. 449-470 (1995)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Obayashi, M.and Y.Fukao: "P and PcP travel time tomography for the core-mantle boundary" J.GeoPhys.Res.102. 17825-17841 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Obayashi, M.and Y.Fukao: "PcP travel time tomography for the core-mantle boundary" J.GeoPhys.Res.102. 17825-17841 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Sugioka, H., Y.Fukao and S.Sakai: "Anomalously Early First Arrivals to the J-array from Teleseimic Events" J.Phys.Earth. 44. 687-699 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Fukao, Y.: "Single-force representation of eartquakes due to landslides or the collapse of caverns" GeoPhys.J.Int.122. 243-248 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Geller.R.J.and N.Takeuchi: "A new method for computing highly accurate DSM synthetic seismograms" GeoPhys.J.Int.123. 449-470 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] 大林政行・桜井太郎・深尾良夫: "走時インバージョンによるマントル3次元構造" 地学雑誌. 104. 934-940 (1995)

    • Related Report
      1995 Annual Research Report
  • [Publications] 島崎邦彦: "海底活断層調査と地震発生の長期予測-浅海から深海へ-" 月刊地球. 501-503 (1995)

    • Related Report
      1995 Annual Research Report
  • [Publications] 武尾 実・吉田茂生: "Source Process of the 1955 Kobe Earthquake Determination of Spati-Temporal Slip Distribution" B.S.S.A. (in press). (1996)

    • Related Report
      1995 Annual Research Report
  • [Publications] S.Ide・M.Takeo: "The dynamic rupture process of the 1993 Kushiro-oki earthquake" J.G.R.(in press). (1996)

    • Related Report
      1995 Annual Research Report
  • [Publications] 山田功夫.近藤恵子: "GPS受信機を利用した刻時装置" 地震. 2. 429-431 (1995)

    • Related Report
      1995 Annual Research Report
  • [Publications] Tomizawa・I.Yamada: "Generation Mechanism of Electric Impulses Observed in Explosion Seismic Experiments" Geomg.Greoelectr.47. 313-324 (1995)

    • Related Report
      1995 Annual Research Report
  • [Publications] Fukao,Y.,M.Obayashi,H Inoue and M.Nenbai: "Subducting slabs stagnant in the mantle transition zone" J.geophys.Res.97. 4804-4822 (1992)

    • Related Report
      1994 Annual Research Report
  • [Publications] Fukao,Y.: "Seismic tomogram of the Earth's mantle:Geodynamic implications" Science. 258. 625-630 (1992)

    • Related Report
      1994 Annual Research Report
  • [Publications] 島崎邦彦: "活断層から推定される地震の再来期間" 月刊地球 5. 199. 78-79 (1992)

    • Related Report
      1994 Annual Research Report
  • [Publications] Takeo,M.,S.Ide and Y.Toshida: "The 1993 kushiro-oki,Japan,Earthquake:a high stress-drop event in a subducting slab" Geophys.Res.Lett.20. 2607-2610 (1993)

    • Related Report
      1994 Annual Research Report
  • [Publications] 梶川昌三・山田功夫・深尾良夫: "岩石破壊実験による地震発生直前の地殻の状態" 地震. 46. 229-235 (1993)

    • Related Report
      1994 Annual Research Report
  • [Publications] Hara,T.,S.Tsuboi and R.J.Geller: "Inversion for laterally heterogeneous upper mantle S-wave velocity structure usiing iterative waveform inverison" Geophys.J.Int.667-698 (1993)

    • Related Report
      1994 Annual Research Report
  • [Publications] Yoshio Fukao: "Seismic tomograph of the Earth mantle:Geodynamic Implications" Science. 258. 625-630 (1992)

    • Related Report
      1993 Annual Research Report
  • [Publications] Yoshio Fukao: "ESR Dating of pleistocene fossil shells of the Atsumi group,central Honshu,Japan:On the discrepancy in TD value among different ESR peaks" Applied Radiation and Isotopes. (in press). (1993)

    • Related Report
      1993 Annual Research Report
  • [Publications] Isao Yamada: "岩石破壊実験による地震発生直前の地殻の状態" 地震. 46. 229-235 (1993)

    • Related Report
      1993 Annual Research Report
  • [Publications] Minoru Takeo: "THE 1993 KUSHIRO-OKI,JAPAN,EARTHQUAKE:A HIGH STRESS-DROP EVENT IN A SUBDUCTIONG SLAB" Geophysical Research Letters. 20. 2607-2610 (1993)

    • Related Report
      1993 Annual Research Report
  • [Publications] R.J.Geller: "Anomalously large near-field Rayleigh waves excited by the 1992 Landers,California,earthquake" Bull.Seism.Soc.Am.(in press). (1994)

    • Related Report
      1993 Annual Research Report
  • [Publications] R.J.Geller: "DSM coomplete synthetic seismograms SH,spherically symmetric case" Geophys.Res.Lett.(in press). (1994)

    • Related Report
      1993 Annual Research Report

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Published: 1993-04-01   Modified: 2017-10-06  

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