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2002 Fiscal Year Final Research Report Summary

Rate of displacement and recurrence time of earthquake of the submarine active fault off Tokai

Research Project

Project/Area Number 11309002
Research Category

Grant-in-Aid for Scientific Research (A)

Allocation TypeSingle-year Grants
Section一般
Research Field 広領域
Research InstitutionThe University of Tokyo

Principal Investigator

TOKUYAMA Hidekazu  The University of Tokyo, Ocean Research Institute, Professor, 海洋研究所, 教授 (10107451)

Co-Investigator(Kenkyū-buntansha) NAKAMURA Yasuyuki  The University of Tokyo, Ocean Research Institute, Research Associate, 海洋研究所, 助手 (60345056)
MURAYAMA Masafumi  Kochi University, Core Research Center, Associate Professor, 海洋コア総合研究センター, 助教授 (50261350)
ASHI Juichiro  The University of Tokyo, Ocean Research Institute, Associate Professor, 海洋研究所, 助教授 (40251409)
TAIRA Asahiko  Center for Deep Earth Exploration(CDEX)Japan Marine Science and Technology Center, Director-General(Researcher), 地球深部探査センター, センター長(研究職) (50112272)
Project Period (FY) 1999 – 2002
KeywordsSubmarine active fault / Deep Tow survey / Enshu Fault system / High resolution underwater positioning system / Piston core / Responder / decollement / the paleo-Zenisu ridge
Research Abstract

The objectives of this research program is 1)to establish the method of deep-sea active fault surveying system(integration of high resolution underwater positioning system + deeptow surveying system, and high resolution underwater positioning system + pinpoint sampling system from oceanfloor),and 2) to determine the rate of offset of the active faults off Tokai and the recurrence time of great earthquake using the method of deep-sea active fault surveying system. In the first two years, we spent our time to construct new survey method.
In 2001, we applied our new method to the Enshu fault system located in Kumano Basin using Hakuho-maru. The Enshu fault system is characterized by dextral fault with vertical displacement and mudvokanoes are aligned on the fault. We can identify displacements on the mudvolcanoes induced by fault movement.
As a first step, we performed remote sensing survey across the Enshu fault system using a high resolution underwater positioning system + deeptow surveyi … More ng system, and obtained high resolution bathymetric map with a 2m counter, backscattering image of ocean floor, and subbottom cross section across the Enshu Faults system. Next, we selected two position for sampling where the rate of displacement is likely to be calculated based on the remote sensing data, and performed piston core sampling using responders attached on piston corer.
The operation to make the piston core approach to the intended sampling point with high accuracy requires a high ship navigation technique in case of no remote operation capability installed on the piston core. But the high ship navigation technique of the crew members of Hakuho-maru enable to take samples from the intended points.
The results of core sample analysis revealed, we can not estimate the recurrence time of great earthquake, becausecorrelated layers are not identified hi the cores obtained from the two sites. So, we tried to estimate the recurrence time of great earthquake based on the event time of mud vokano eruption, assuming that the mud eruption corresponds with the earthquake event inducing the displacement of fault. Isotropic age determination revealed that the youngest age of the mud eruption event is 23KMa. So, we can not estimate the recurrence time of earthquake.
We applied 3D pre-stack depth migration process to the 3D MCS data sets obtained from Kodaiba fault system in order to clarify the structural relationship between surface manifestation of the Kodaiba fault system and the deep seated decollement(seismogenic zone? ). The results of the process suggests that 1)the decollement is characterized by high reflectivity in a range of 5km from the point where the Kodaiba fault system merges with decollement(seismic nuclear? ), 2) the decollement is identified not continuously but intermittently, and 3)subducted ridge(the paleo-Zenisu ridge) is identified beneath the lower slope. Less

  • Research Products

    (22 results)

All Other

All Publications (22 results)

  • [Publications] 徳山 英一: "相模湾・駿河湾の湧水活動"海洋と生物. 141. 290-293 (2002)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 徳山 英一: "海底湧水の特徴"海洋と生物. 141. 278-282 (2002)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Wonn Soh: "Rejuvenation of submarine canyon associated with ridge subduction, Tenryu Canyon, off Tokai, central Japan"Marine Geology. 187(1-2). 203-220 (2002)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 徳山 英一: "日本周辺海域中新世最末期以降の構造発達史"海洋調査技術. 13(1). 27-53 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 徳山 英一: "メタンハイドレートからみた間隙流体移動と湧水活動"月刊地球. 23. 823-827 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 芦寿一郎: "熊野沖南海トラフ付加プリズムの地質と構造と冷湧水"深海研究. 20. 1-8 (2002)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Juichiro Ashi: "Distribution of methane hydrate BSRs and its implication for the prism growth in the Nankai Trough"Marine Geology. 187(1-2). 177-191 (2002)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 芦寿一郎: "メタンハイドレートと冷湧水からみた沈み込み帯の物質循環-南海トラフ付加プリズムの例-,プレート沈み込み帯における物質循環 -付加体の役割-"月刊地球. 号外(32). 122-129 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 平 朝彦: "プレート沈み込み帯における物質循環 -付加体の役割-"月刊地球. 号外(32). 6-12 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 氏家由利香, 平 朝彦: "琉球海溝・南海トラフ域におけるマッドダイアピルの活動,プレート沈み込み帯における物質循環 -付加体の役割-"月刊地球. 号外(32). 206-213 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 徳山 英一: "東海沖の活断層"東京大学出版会. 1-178 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Hidekazu Tokuyama: "Cold seepage activity in the Bays of Sagami and Suruga"Aquabiology. 141. 290-293 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Hidekazu Tokuyama: "Characterization of submarine seepage activity"Aquabiology. 141. 278-282 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Won Soh: "Rejuvenation of submarine canyon associated with ridge subduction, Tenryu Canyon, off Tokai, central Japan"Marine Geology. 187(1-2). 203-220 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Hidekazu Tokuyama: "Tectonic development in the regious around Japan since latest Miocene"Journal of the Japan Society for Marine Surveys and Technology. 13(1). 27-53 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Hidekazu Tokuyama: "Pore fluid water migration and cold seepage activity in related to methane hydrate"Chikyu Monthly. 23. 823-827 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Juichiro Ashi: "Geology, Structure, and cold seepage activity in the Nankai accretionary prism off Kumano"JAMSTEC Deep Sea Research. 20. 1-8 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Juichiro Ashi: "Distribution of methane hydrate BSRs and its imlication for the growth in the Nanki Trough"Marine Geology. 187(1-2). 177-191

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Juichiro Ashi: "Mass Balance of the subduction zone in relation to methane hydrate and cold seepage activity"Chikyu Monthly. 32(Special Volume). 122-129 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Asahiko Taira: "Mass balance in the plate subduction zone"Chikyu Monthly. 32(Special Volume). 6-12 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Urika Ujiie, Asahiko Taira: "Activity of mud diapir in the Ryukyu Trench and Nankai Trough"Chikyu Monthly. 32(Special Volume). 206-213 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Hidekazu Tokuyama: "Submarine Active Fault off Tokai"The Tokyo University Press. 1-178 (1999)

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

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Published: 2004-04-14  

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