海底電磁気機動観測でスタグナントスラブを診る

2008 Fiscal Year Annual Research Report

• Project/Area Number: 16075204
• Research Institution: The University of Tokyo
• Principal Investigator: 歌田 久司 The University of Tokyo, 地震研究所, 教授 (70134632)
• Keywords: 地球深部スラブ / 地球電磁気観測 / 電気伝導度 / マントル遷移層 / 海底電磁力計 / 水 / フィリピン海 / 電磁気トモグラフィー

Research Abstract

海底長期観測設置航海を計画研究ウと共同で実施するとともに、得られたデータと既存データの統合解析を進めた。実績の概要は以下の通りである。
(1) 長期型海底電磁力計によるフィリピン海での観測の終了
計画研究ウとの協力のもとで11月15日〜12月1日に実施したフィリピン海における「かいれい」航海により、前年度に設置した14台のOBEMを全て回収した。
(2) 解析手法の開発・改良
本研究者らが世界に先駆けて実用化したグローバルスケールの電磁気トモグラフィー解析手法に加え,リージョナルスケールのトモグラフィー解析を可能にする計算機コードの開発をすすめた。
(3) 国内外の既存の電磁気観測データの収集・コンパイル
昨年度に引き続き、すでにデータベース化している海半球観測ネットワークの電磁気長期観測データに加えて,研究対象地域およびその周辺で行われている長期地磁気観測データなどをコンパイルし、1次元標準構造の見直しを行なった。
(4) マントル遷移層内の水に関する新たな知見
データ解析により,地中海の沈み込み帯から沈み込みヨーロッパの下で滞留するスラブの電気伝導度を明らかにした.この結果と西太平洋沈み込み帯の結果を比較したところ,ヨーロッパではほとんど水が存在しないのに対し,西太平洋では1重量%もの水の存在が示唆された.

Research Products

• [Journal Article] A joint interpretation of electromagnetic and seismic tomography models suggests the mantle transition zone below Europe is dry (2009)
  • Author(s): Utada, H., Koyama, T., Obayashi, M., Fukao, Y.
  • Journal Title: Earth Planet. Sci. Lett 281 Pages: 249-257
  • Peer Reviewed
• [Journal Article] Ocean Bottom Array Probes Stagnant Slab Beneath the Philippine Sea (2009)
  • Author(s): Shiobara, H., K. Baba, H. Utada and Y. Fukao
  • Journal Title: EOS, Trans. AGU 90-9 Pages: 70-71
  • Peer Reviewed
• [Journal Article] Three-Dimensional Geomagnetic Response Functions For Global And Semi-Global ScaleInduction Problems (2009)
  • Author(s): Shimizu, H., Koyama, T., Baba, K., Utada, H.
  • Journal Title: Geophysical J. Int 177(in press)
  • Peer Reviewed
• [Journal Article] Recent progress of the electro-magnetic survey to investigate Earth's interior (2009)
  • Author(s): Kasaya, T., T. Goto, K. Baba, M. Kinoshita, Y. Hamano, and Y. Fukao
  • Journal Title: JAMSTEC Report of Research and Development 8(印刷中)
• [Journal Article] Resistivity structure of Unzen Volcano derived from time domain electromagnetic (TDEM) survey (2008)
  • Author(s): Srigutomo, W., Kagiyama, T., Kanda, W., Munekane, H., Hash imoto, T., Tanaka, Y., Utada, H ., and Utsugi, M.
  • Journal Title: J. Volcanol. Geotherm. Res 175 Pages: 231-240
  • Peer Reviewed
• [Journal Article] Impedance tensor of Network-MT and the influencing factors (2008)
  • Author(s): Chen, X.B., Zhao, G.Z., Tang, J., Uyeshima, M., and Utada, H.
  • Journal Title: Chinese J. Geophys 51 Pages: 273-279
  • Peer Reviewed
• [Presentation] A reference 1-D model of electrical conductivity for the upper mantle beneath the Philippine Sea (2009)
  • Author(s): Baba, K., H. Utada, H. Shimizu, T. Goto, T. Kasaya, N. Tada, T. Koyama, and M. Uyeshima
  • Organizer: Stagnant Slab Project International Symposium
  • Place of Presentation: 京都
  • Year and Date: 2009-02-26
• [Presentation] An indication of electrical anisotropy in the upper mantle beneath the West Philippine Basin (2009)
  • Author(s): Baba, K.
  • Organizer: Stagnant Slab Project International Symposium
  • Place of Presentation: 京都
  • Year and Date: 2009-02-26
• [Presentation] Toward 3-D inversion of seafloor MT data collected by Stagnant Slab Project (2009)
  • Author(s): Tada, N., K. Baba, W. Siripunvaraporn, M. Uyeshima, and H. Utada
  • Organizer: Stagnant Slab Project International Symposium
  • Place of Presentation: 京都
  • Year and Date: 2009-02-26
• [Presentation] Is the mantle transition zone globally dry? -Observational evidence from electrical conductivity (2009)
  • Author(s): Utada, H., H. Shimizu, K. Baba.
  • Organizer: Stagnant Slab Project International Symposium
  • Place of Presentation: 京都
  • Year and Date: 2009-02-26
• [Presentation] Electrical structure in the mantle across the Mariana subduction system (2009)
  • Author(s): Matsuno, T., N. Seama, K. Baba, T. Goto, A. Chave, R. L. Evans, A. White, G. Boren, A. Yoneda, H. Utada, H. Graham, and K. Suyehiro
  • Organizer: Stagnant Slab Project International Symposium
  • Place of Presentation: 京都
  • Year and Date: 2009-02-26
• [Presentation] Completion of three-year observation by BBOBSand OBEM arrays probing the stagnant slab (2008)
  • Author(s): Baba, K., H. Shiobara, T. Goto, H. Sugioka, T. Kasaya, A. Ito, T. Isse, A. Shito, T. Ichikita, T. Kanazawa, H. Utada
  • Organizer: AGU 2008 fall meeting
  • Place of Presentation: サンフランシスコ
  • Year and Date: 2008-12-16
• [Presentation] On one-dimensional mantle conductivity modeling of 3-dimensional Earth (2008)
  • Author(s): H. Utada, H. Shimizu, K. Baba, T. Koyama
  • Organizer: AGU 2008 fall meeting
  • Place of Presentation: サンフランシスコ
  • Year and Date: 2008-12-15
• [Presentation] Is the mantle transition zone globally dry? : Observational evidence from electrical conductivity (2008)
  • Author(s): H. Utada, H. Shimizu, K. Baba, T. Koyama
  • Organizer: AGU 2008 fall meeting
  • Place of Presentation: サンフランシスコ
  • Year and Date: 2008-12-13
• [Presentation] Electrical structure beneath the central Mariana subduction fore-arc, arc, back-arc system (2008)
  • Author(s): Matsuno, T., N. Seama, K. Baba, T. Goto, A. Chave, R. Evans, A. White, G. Boren, A. Yoneda, G. Heinson, H. Iwamoto, R. Tsujino, Y. Baba, H. Utada, and K. Suyehiro
  • Organizer: The 19th International Workshop on Electromagnetic Induction in the Earth
  • Place of Presentation: 中国・北京
  • Year and Date: 2008-10-28
• [Presentation] Application of independent component analysis on estimation of electromagnetic response functions in a period range of 104-105 seconds (2008)
  • Author(s): BABA, K. and UTADA, H.
  • Organizer: International Workshop on EM induction
  • Place of Presentation: 北京
  • Year and Date: 2008-10-25
• [Presentation] Effect of Sq variations on the electromagnetic response functions in the period range between 3 hours and 1 day (2008)
  • Author(s): UTADA, H., YONEDA, A., SHIMIZU, H., BABA, K., PALSHIN, N.
  • Organizer: International Workshop on EM induction
  • Place of Presentation: 北京
  • Year and Date: 2008-10-24
• [Presentation] Three-dimensional geomagnetic response functions for global and semi-global scale induction problems (2008)
  • Author(s): SHIMIZU H., KOYAMA T., BABA K.. UTADA H.
  • Organizer: International Workshop on EM induction
  • Place of Presentation: 北京
  • Year and Date: 2008-10-24
• [Presentation] Modification of a 3-D magnetotelluric forward code considering topography effect in order to estimate 3-D conductivity structures of oceanic upper mantle using inversion method (2008)
  • Author(s): Tada, N., K. Baba, W. Siripunvaraporn, M. Uyeshima, and H. Utada
  • Organizer: The 19th International Workshop on Electromagnetic Induction in the Earth
  • Place of Presentation: 中国・北京
  • Year and Date: 2008-10-24
• [Presentation] Possible Observational constraints on lateral electrical conductivity contrast in the deep mantle (2008)
  • Author(s): Hisayoshi. Shimizu, Hiromichi Nazao. and Hisashi Utada
  • Organizer: International Workshop on Transport Properties in the LOwer Mantle
  • Place of Presentation: 湯西川(栃木)
  • Year and Date: 2008-10-23
• [Presentation] Revised electrical conductivity structure of the upper and mid-mantle in the North Pacific region (2008)
  • Author(s): Hisayoshi Shimizu, Takao Koyama, Kiyoshi Baba, and Hisashi Utada
  • Organizer: 地球電磁気・地球惑星圏学会
  • Place of Presentation: 仙台
  • Year and Date: 2008-10-09
• [Presentation] 3時間〜1日の電磁気応答関数に見られるSqの影響 (2008)
  • Author(s): 米田朝美, 清水久芳, 馬場聖至, 歌田久司
  • Organizer: 日本地球惑星科学連合2008年大会
  • Place of Presentation: 幕張メッセ国際会議場
  • Year and Date: 2008-05-29
• [Presentation] 中部マリアナ沈み込み・前弧・島弧・背弧系の比抵抗構造 (2008)
  • Author(s): 松野哲男, 島伸和, 馬場聖至, 後藤忠徳, Alan Chave, Rob L. Evans, Antony White, Goran Boren, 米田朝美, Graham Heinson, 岩本久則, 辻野良輔, 馬場祐太, 歌田久司, 末広潔
  • Organizer: 2008年地球惑星科学連合大会
  • Place of Presentation: 幕張メッセ国際会議場
  • Year and Date: 2008-05-28
• [Presentation] スタグナントスラブ計画により得られた海底電磁気データの解析 (2008)
  • Author(s): 馬揚聖至, 後藤忠徳, 笠谷貴史, 一北岳夫, 小山崇夫, 清水久芳, 多田訓子, 上嶋誠, 歌田久司
  • Organizer: 2008年地球惑星科学連合大会
  • Place of Presentation: 幕張メッセ国際会議場
  • Year and Date: 2008-05-27
• [Presentation] Three dimensional geomagnetic response functions for global and semi-global scale induction problems (2008)
  • Author(s): Hisayoshi Shimizu, Takao Koyama, Kiyoshi Baba, Hisashi Utada
  • Organizer: 日本地球惑星科学連合2008年大会
  • Place of Presentation: 幕張メッセ国際会議場
  • Year and Date: 2008-05-27
• [Remarks]
  • URL: http://ohp-ju.eri.u-tokyo.ac.jp/tokutei/