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Strain accumulation process and interplate coupling in the Nankai region, Southwest Japan

Research Project

Project/Area Number 06640549
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field 固体地球物理学
Research InstitutionKochi University

Principal Investigator

TABEI Takao  Kochi Univ., Fac.of Science, Associate Professor, 理学部, 助教授 (40207220)

Co-Investigator(Kenkyū-buntansha) KIMURA Shozo  Fac.of Science, Associate Professor, 理学部, 助教授 (70036549)
Project Period (FY) 1994 – 1996
Project Status Completed (Fiscal Year 1996)
Budget Amount *help
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1996: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1995: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1994: ¥800,000 (Direct Cost: ¥800,000)
KeywordsGPS / Interplate interaction / Crustal strain / Nankai trough / プレート間カップリング
Research Abstract

The Nankai region is located in one of the most active plate-subduction zones in Japan, where earthquake deformation cycle caused by the subduction of the Philippine Sea plate beneath the Eurasian plate is very clear as shown by the occurrence of great interplate earthquake within the short span of 100-130 years. We deployed GPS observation network to clarify strain accumulation process and discuss dynamics of the interplate interaction.
Results obtained from three-year GPS measurements are as follows : 1. All stations have been displaced toward the west-northwest to northwest direction, 2. Displacement velocity is maximum at the southernmost site and rapidly dicreases with increasing distance from the plate boundary, and 3. Large displacement gradient exists in a narrow region extending parallel to the strike of the plate boundary. These results imply that current interplate coupling at the Nankai trough is strong ; much of the relative plate motion has been taken up by deformation of the leading edge of the Eurasian plate.
Using an inversion technique of GPS-derived displacement velocity, we estimated strength of interplate coupling at the Nankai trough. Strong coupling thus estimated is in striking contrast to the weak interaction in the Tohoku region where considerable part of relative plate motion may be taken up by aseismic "slow" or "silent" slip. Furthermore, we discussed more regional deformation field based on the results by the nationwide GPS network by Geographical Survey Institute. We pointed out eastward motion in Chugoku region, which is small but systematically contradictory to the subduction of the Philippine Sea plate. One of the interpretations is that southwest Japan belongs to the "Amurian" microplate which is considered to have a slight eastward velocity and eastward motion of southwest Japan is constrained to reduce by the collision with northeast Japan and/or by the interaction with the Philippine Sea plate.

Report

(4 results)
  • 1996 Annual Research Report   Final Research Report Summary
  • 1995 Annual Research Report
  • 1994 Annual Research Report
  • Research Products

    (20 results)

All Other

All Publications (20 results)

  • [Publications] 田部井隆雄・他: "GPS観測より求めた四国地方南東部の地殻水平変動" 地震2. 47(3). 303-310 (1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Date,Y.et al.: "Crustal deformation in Shikoku region,Southwest Japan,derived from GPS surveys -Results from 1990 to 1994-" Proceedings of the Japanese Symposium on GPS (1994). 203-209 (1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] 木村昌三・岡野健之助: "1946年南海地震直前の南海地域における地震活動の低下" 地震2. 48(2). 213-221 (1995)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Tabei,T.et al.: "Crustal deformation at the Nankai subduction zone,southwest Japan,derived from GPS measurements" Geophysical Research Letters. 23(21). 3059-3062 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Tabei,T.et al.: "Crustal deformation associated with the 1995 Hyogo-ken Nanbu earthquake,Japan derived from GPS measurements" Journal of Physics of the Earth. 44(4). 281-286 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] 岡野健之助・木村昌三: "南海地震に関連する四国およびその周辺の地盤変動" 地震2. 49(3). 361-374 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Tabei, T.et al: "Horizontal crustal deformation in southern part of Shikoku, southwest Japan, deduced from GPS surveys" Zisin (Journal of Seismological Society of Japan). 47 (3). 303-310 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Date, Y.et al.: "Crustal deformation in Shikoku region, southwest Japan, derived from GPS surveys-Results from 1990 to 1994" Proceedings of the Japanese Symposium on GPS (1994). 203-209 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Kimura, S.and K.Okano: "A lowering of seismic activity in the Nankai district, southwest Japan, just before the 1946 Nankai earthquake" Zisin (Journal of Seismological Society of Japan). 48 (2). 213-221 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Tabei, T.et al: "Crustal deformation at the Nankai subduction zone, southwest Japan, derived from GPS measurements" Geophysical Research Letters. 23 (21). 3059-3062 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Tabei, T.et al: "Crustal deformation associated with the 1995 Hyogo-ken Nanbu earthquake, Japan derived from GPS measurements" Journal of Physics of the Earth. 44 (4). 281-286 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Okano, K.and S.Kimura: "Crustal movements in and around Shikoku, southwest Japan associated with Great Nankai earthquakes" Zisin (Journal of Seismological Society of Japan). 49 (3). 361-374 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1996 Final Research Report Summary
  • [Publications] Tabei,T.et al.: "Crustal deformation at the Nankai subduction zone,southwest Japan,derived from GPS measurements" Geophysical Research Letters. 23(21). 3059-3062 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] Tabei,T.et al.: "Crustal deformation associated with the 1995 Hyogo-ken Nanbu earthquake,Japan derived from GPS measurements" Journal of Physics of the Earth. 44(4). 281-286 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] Hirahara,K.et al.: "GPS observation of postseismic crustal movements in the focal region of the 1995 Hyogo-ken Nanbu earthquake" Journal of Physics of the Earth. 44(4). 300-312 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] 岡野健之助・木村昌三: "南海地震に関連する四国およびその周辺の地盤変動" 地震2. 49(3). 361-374 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] 田部井隆雄: "GPS -地球科学へのインパクト-" 月刊地球. 号外11. 107-112 (1995)

    • Related Report
      1995 Annual Research Report
  • [Publications] Takao TABEI: "Crustal deformation associated with the 1995 Hyogo-ken Nanbu earthquake, Japan derived from GPS measurements" Special Issue on the 1995 Hyogo-ken Nanbu earthquake, Journal of Physics of the Earth. (in press). (1996)

    • Related Report
      1995 Annual Research Report
  • [Publications] 木村昌三: "1946年南海地震直前の南海地域における地震活動の低下" 地震第2輯. 48. 213-221 (1995)

    • Related Report
      1995 Annual Research Report
  • [Publications] 田部井隆雄・他: "GPS観測より求めた四国地方南東部の地殻水平変動" 地震2. 47. 303-310 (1994)

    • Related Report
      1994 Annual Research Report

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Published: 1994-04-01   Modified: 2016-04-21  

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