延岡衝上断層下盤メランジュの変形機構の解明

2013 Fiscal Year Research-status Report

• Project/Area Number: 25800283
• Research Category: Grant-in-Aid for Young Scientists (B)
• Research Institution: National Institute of Advanced Industrial Science and Technology
• Principal Investigator: 北島 弘子 独立行政法人産業技術総合研究所, 活断層・火山研究部門, 研究員 (60635796)
• Project Period (FY): 2013-04-01 – 2015-03-31
• Keywords: 変形実験 / メランジュ / 延岡衝上断層

Research Abstract

本研究では沈み込み帯全体における歪蓄積・開放の収支の解明にむけて，深部付加体を構成するメランジュの力学特性を明らかにすることを目的に，延岡衝上断層下盤メランジュの高温高圧三軸変形実験をおこなった．延岡衝上断層掘削コアのメランジュサンプルをメランジュが形成されたとする高温下(250 ℃)にて，ガス圧式高温高圧変形実験装置を使用して変形させた．圧力条件としては， (1) 封圧 = 200 MPa, 間隙水圧 = 80 MPa，有効圧 ＝ 120 MPa，および (2) 封圧 = 200 MPa, 間隙水圧 = 180 MPa，有効圧 ＝ 20 MPa を設定した．この二つの圧力条件は，(1) 間隙水圧が静水圧の場合，(2) 間隙水圧が静岩圧に近い場合の地下約8 kmを再現している．軸変位速度は0.05-0.5 micron/s（ひずみ速度 1.6×10-6 - 2.0×10-5 s-1に相当）とし，封圧・間隙水圧は変形中は一定に保った．
変形実験の結果，延岡衝上断層下盤メランジュは(1) 間隙水圧が静水圧条件下では延性的に，(2) 間隙水圧が静岩圧に近い条件では脆性的に変形することが分かった．延岡衝上断層下盤メランジュは(1) 有効圧 = 120 MPaのときには差応力120-160 MPaで降伏し，定常状態で差応力約300 MPaを示した．一方，(2)有効圧 = 20 MPaの場合には差応力30-70 MPaで降伏，65-90 MPaでピークに達した後，10-30 MPaの応力降下を示し，残留強度は40-60 MPaであった．今後延岡衝上断層上盤千枚岩についても同様の実験を行い比較する予定である．

Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

これまで研究は順調に推移しており，高温高圧下での三軸実験の結果がまとまりつつある。

Strategy for Future Research Activity

これまでに延岡衝上断層の下盤メランジュの力学・変形特性が明らかになったので，今後は断層の上盤を構成する千枚岩についても同様に高温高圧下での変形実験を行い力学・変形特性を明らかにする．

Expenditure Plans for the Next FY Research Funding

長期出張中（航海乗船含む）のため予定していた国内外の学会に参加・成果発表ができなかった．
次年度(2014年4月)に国際学会で研究成果発表する予定である。

Research Products

• [Journal Article] Displacement and dynamic weakening processes in smectite-rich gouge from the Central Deforming Zone of the San Andreas Fault (2014)
  • Author(s): French, M. E., H. Kitajima, J. S. Chester, F. M. Chester, and T. Hirose
  • Journal Title: Journal of Geophysical Research, Solid Earth Volume: 119 Pages: 1777-1802
  • DOI: 10.1002/2013JB010757
  • Peer Reviewed
• [Journal Article] Hydraulic and acoustic properties of the active Alpine Fault, New Zealand: Laboratory measurements on DFDP-1 drill core (2014)
  • Author(s): Carpenter, B. M., H., Kitajima, R., Sutherland, J., Townend, V. G., Toy, and D. M., Saffer
  • Journal Title: Earth and Planetary Science Letters Volume: 390 Pages: 45-51
  • DOI: 10.1016/j.epsl.2013.12.023
  • Peer Reviewed
• [Journal Article] NanTroSEIZE Stage 3: NanTroSEIZE plate boundary deep riser 2 (2014)
  • Author(s): Moore, G. F., K., Kanagawa, M., Strasser, B., Dugan, L., Maeda, S., Toczko, and IODP Expedition 338
  • Journal Title: Scientific Drilling Volume: 17 Pages: 1-12
  • DOI: 10.5194/sd-17-1-2014
  • Peer Reviewed
• [Journal Article] NanTroSEIZE Stage 3: NanTroSEIZE plate boundary deep riser 2 (2014)
  • Author(s): Strasser, M., B. Dugan, K. Kanagawa, G.F. Moore, S. Toczko, L. Maeda, and the Expedition 338 Scientists
  • Journal Title: IODP Prodeedings Volume: 338 Pages: 1-633
  • DOI: 10.2204/iodp.proc.338.2014
• [Presentation] Stress states and physical properties along the Nankai Trough plate boundary
  • Author(s): Kitajima, H., and Saffer D. M.
  • Organizer: Japan Geoscience Union Meeting 2013
  • Place of Presentation: 幕張メッセ
  • Invited
• [Presentation] ドレライト粉砕ガウジの低～高速摩擦特性
  • Author(s): 和田純一, 野田博之, 岡崎啓史, 大橋聖和, 北島弘子, 高橋美紀, 金川久一
  • Organizer: Japan Geoscience Union Meeting 2013
  • Place of Presentation: 幕張メッセ
• [Presentation] Frictional behavior and BET surface are changes of SAFOD gouge at intermediate to seismic slip rates
  • Author(s): Sawai, M., Shimamoto, T., Mitchell, T., Kitajima, H., and Hirose T.
  • Organizer: European Geosciences Union General Assembly 2013
  • Place of Presentation: Austria Center Austria Center Vienna, Vienna, Austria
• [Presentation] Physical properties and Consolidation behavior of sediments from the N. Japan subduction zone
  • Author(s): Valdez, R. D., R. M., Lauer, M., Ikari, H., Kitajima, and D. M., Saffer
  • Organizer: American Geophysical Union 2013 Fall Meeting
  • Place of Presentation: Moscone Center, San Francisco, U.S.A.
• [Presentation] Porosity, Pore Size, and Permeability of Sediments from Site C0002, IODP Expedition 338
  • Author(s): Dugan, B., A., Huepers, I., Song, H., Kitajima, and L., Esteban
  • Organizer: American Geophysical Union 2013 Fall Meeting
  • Place of Presentation: Moscone Center, San Francisco, U.S.A.
• [Presentation] Smectite-illite transition during coseismic slip
  • Author(s): Takahashi, M., and H. Kitajima
  • Organizer: American Geophysical Union 2013 Fall Meeting
  • Place of Presentation: Moscone Center, San Francisco, U.S.A.
• [Presentation] ドレライト粉砕ガウジの低～高速摩擦特性
  • Author(s): 和田純一,金川久一,大橋聖和, 高橋美紀, 北島, 弘子,井上厚行,廣瀬丈洋,安東淳一
  • Organizer: 日本地質学会第120年学術大会
  • Place of Presentation: 東北大学川内北キャンパス
• [Presentation] Physical properties of Nankai accretionary prism sediments at Site C0002, IODP Expedi- tion 348
  • Author(s): Kitamura, M., Kitajima, H., Henry, P.,Valdez, R., J. Matthew, and Expedition 348 Scientists
  • Organizer: Japan Geoscience Union Meeting 2014
  • Place of Presentation: Pacifico Yokohama, Yokohama
• [Presentation] Approximate General Coulomb Model for Accretionary Prisms: An Integrated Study of the Kumano Transect, Nankai Subduction Zone, Southwest Japan
  • Author(s): Skarbek, R., M. Ikari, A. Hupers, A. Rempel, D. WIlson, and H. Kitajima
  • Organizer: European Geosciences Union General Assembly 2014
  • Place of Presentation: Austria Center Austria Center Vienna, Vienna, Austria
• [Presentation] Mechanical properties of foliated cataclasites from the Nobeoka thrust
  • Author(s): Kitajima, H., M. Takahashi, G. Kimura, A. Yamaguchi, S. Saito, M. Hamahashi, R. Fukuchi, J. Kameda, Y. Hamada, K. Fujimoto, Y. Hashimoto, Y. Kitamura, S. Hina, and M. Eida
  • Organizer: European Geosciences Union General Assembly 2014
  • Place of Presentation: Austria Center Austria Center Vienna, Vienna, Austria
• [Presentation] Physical properties of the Nankai inner accretionary prism at Site C0002, IODP Expedition 348
  • Author(s): Kitamura, M., Kitajima, H., Henry, P.,Valdez, R., J. Matthew, and Expedition 348 Scientists
  • Organizer: European Geosciences Union General Assembly 2014
  • Place of Presentation: Austria Center Austria Center Vienna, Vienna, Austria