海底電磁気観測網を生かしたマントル遷移層内水分布イメージングの革新

• Project/Area Number: 15K05262
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Solid earth and planetary physics
• Research Institution: The University of Tokyo
• Principal Investigator: 馬場 聖至 東京大学, 地震研究所, 助教 (70371721)
• Co-Investigator(Kenkyū-buntansha): 小山 崇夫 東京大学, 地震研究所, 助教 (00359192)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Project Status: Granted (Fiscal Year 2017)
• Budget Amount: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000); Fiscal Year 2018: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000); Fiscal Year 2017: ¥390,000 (Direct Cost: ¥300,000、Indirect Cost: ¥90,000); Fiscal Year 2016: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000); Fiscal Year 2015: ¥390,000 (Direct Cost: ¥300,000、Indirect Cost: ¥90,000)
• Keywords: マントル遷移層 / 電気伝導度 / 西太平洋 / 海底電磁気観測 / 水

Outline of Annual Research Achievements

本研究は、西太平洋域における海底電磁気観測データの蓄積を活かした電気伝導度構造イメージングに基づき、この海域下のマントル遷移層内水分布を高分解能かつ定量的に推定することを目指して、それに必要なデータ解析技術を革新的に発展させることを目的としている。
平成29年度は、6月に研究協力者と勉強会を開催した。
電気伝導度構造を推定するためのインバージョン手法に、入力する外部磁場変動について複雑な空間分布に対応させる点と西太平洋域の海底で観測された磁場データから複数のソース変動を分離する点についてそれぞれ以下の進展を得た。
前者について、磁気圏・電離圏物理学分野で研究されているGAIAモデルにより計算される地磁気静穏日変化（Sq）を用い、表層の海陸境界と1次元成層構造を組み込んだ電気伝導度構造による電磁誘導の効果を計算して、実際に地磁気観測点で測定された磁場値との比較を行った。またインバージョンのでは、このテストモデルを用いて感度計算を行い、深さ200～400kmに最も感度が高いことが分かった。
後者について、独立成分分析を応用した予備的な解析を実施した。推定するソース信号の数や各信号の時間変動の特長のほか、パワースペクトルや、混合係数の緯度・経度との相関を詳細に検討した結果、観測された静穏時日変化を定性的にはよく復元するソース信号を推定することに成功した。
これらの成果は、8月にケープタウンで開催されたIAPSO-IAMAS-IAGA Joint Assemblyおよび10月に開催された地球電磁気・地球惑星圏学会講演会で発表した。

Current Status of Research Progress

3: Progress in research has been slightly delayed.

Reason

平成29年度は、複雑な空間分布を持つ外部磁場変動成分を組み込んだインバージョン手法について開発が進み、GAIAモデルにより再現されたSq場を実際に入力したテストを実施することができた。北西太平洋の海底電磁気観測データは、論文として公表できた。一方、実データから外部磁場変動成分を分離する手法についてもSq場を定性的に分離することに試験的には成功したが、あらゆるデータに応用できるよう手法を一般化させる上で、更なる工夫が必要であることが判明した。

Strategy for Future Research Activity

平成30年度は、外部電磁場変動の分離手法の一般化を進める。インバージョン手法も実データを用いた解析を進める。これらの結果について、8月中旬にデンマークで開催される、24th Electromagnetic Induction Workshopにて発表する。また関連研究の進展状況についても情報収集を行う。更に、西太平洋域のマントル電気伝導度モデルを推定し、マントル遷移層内の水分布を定量化を試みる。

Research Products

• [Journal Article] The OJP array: seismological and electromagnetic observation on seafloor and islands in the Ontong Java Plateau (2018)
  • Author(s): Suetsugu D, H. Shiobara, H. Sugioka, N. Tada, A. Ito, T. Isse, K. Baba, H. Ichihara, T. Ota, Y. Ishihara, S. Tanaka, M. Obayashi, T. Tonegawa, J. Yoshimitsu, T. Kobayashi, and H. Utada
  • Journal Title: JAMSTEC Rep. Res. Dev. Volume: 26 Issue: 0 Pages: 54-64
  • DOI: 10.5918/jamstecr.26.54
  • NAID: 130006725610
  • Peer Reviewed / Open Access
• [Journal Article] Hot upper mantle beneath the Tristan da Cunha Hotspot, from probabilistic Rayleigh-wave inversion and petrological modeling (2018)
  • Author(s): Bonadio, R., W. H. Geissler, S. Lebedev, J. Fullea, M. Ravenna, N. L. Celli, W. Jokat, M. Jegen, C. Sens-Schoenfelder, K. Baba
  • Journal Title: Geochemistry, Geophysics, Geosystems Volume: 印刷中
  • DOI: 10.1002/2017gc007347
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Electrical conductivity of the oceanic asthenosphere and its interpretation based on laboratory measurements (2017)
  • Author(s): Katsura, T., K. Baba, T. Yoshino, and T. Kogiso
  • Journal Title: Tectnophysics Volume: 717 Pages: 162-181
  • DOI: 10.1016/j.tecto.2017.07.001
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Electrical conductivity of old oceanic mantle in the northwestern Pacific I: 1-D profiles suggesting differences in thermal structure not predictable from a plate cooling model (2017)
  • Author(s): Baba, K., N. Tada, T. Matsuno, P. Liang, R. Li, L. Zhang, H. Shimizu, N. Abe, N. Hirano, M. Ichiki, and H. Utada
  • Journal Title: Earth, Planets and Space Volume: 69
  • NAID: 120006358589
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Seismicity controlled by resistivity structure: the 2016 Kumamoto earthquakes, Kyushu Island, Japan (2017)
  • Author(s): Aizawa K. et al.
  • Journal Title: Earth Planets and Space Volume: 69 Pages: 1-10
  • DOI: 10.1186/s40623-016-0590-2
  • NAID: 120006360155
  • Peer Reviewed / Open Access
• [Journal Article] Unmanned observations in an area in danger of volcanic eruptions by using an UAV at Kuchinoerabu-jima volcano, southern Kyushu, Japan (2017)
  • Author(s): Ohminato, T., T. Kaneko, T. Koyama, A. Watanabe, W. Kanda, T. Tameguri, and R. Kazahaya
  • Journal Title: Journal of Natural Disaster Science Volume: 38 Pages: 85-104
  • Peer Reviewed / Open Access
• [Journal Article] Mantle transition zone beneath a normal seafloor in the northwestern Pacific: Electrical conductivity, seismic thickness, and water content (2017)
  • Author(s): Matsuno, T., D. Suetsugu, K. Baba, N. Tada, H. Shimizu, H. Shiobara, T. Isse, H. Sugioka, A. Ito, M. Obayashi, and H. Utada
  • Journal Title: Earth and Planetary Science Letters Volume: 462 Pages: 189-198
  • DOI: 10.1016/j.epsl.2016.12.045
  • Peer Reviewed / Open Access
• [Journal Article] Marine magnetotellurics imaged no distinct plume beneath the Tristan da Cunha hotspot in the southern Atlantic Ocean (2017)
  • Author(s): Baba, K., J. Chen, M. Sommer, H. Utada, W. H. Geissler, W. Jokat, and M. Jegen
  • Journal Title: Tectonophysics Volume: 印刷中 Pages: 52-63
  • DOI: 10.1016/j.tecto.2016.09.033
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Three-dimensional resistivity structure of asama volcano revealed by data-space magnetotelluric inversion using unstructured tetrahedral elements (2017)
  • Author(s): Usui Y., Y. Ogawa, K. Aizawa, W. Kanda, T. Hashimoto, T. Koyama, Y. Yamaya, and T. Kagiyama
  • Journal Title: Geophys. J. Int. Volume: 208 Pages: 1359-1372
  • DOI: 10.1093/gji/ggw459
  • NAID: 120006360153
  • Peer Reviewed / Open Access
• [Journal Article] Electromagnetic evidence for volatile-rich upwelling beneath the society hotspot, French Polynesia (2016)
  • Author(s): N. Tada, P. Tarits, K. Baba, H. Utada, T. Kasaya, D. Suetsugu
  • Journal Title: Geophysical Research Letters Volume: 43 Pages: 12012-12026
  • DOI: 10.1002/2016gl071331
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Electrical image of subduction zone beneath northeastern Japan (2015)
  • Author(s): Ichiki, M., Y. Ogawa, T. Kaida, T. Koyama, M. Uyeshima, T. Demachi, S. Hirahara, Y. Honkura, W. Kanda, T. Kono, M. Matsushima, T. Nakayama, S. Suzuki, and H. Toh
  • Journal Title: Journal of Geophysical Research: Solid Earth Volume: 120 Pages: 7937-7965
  • DOI: 10.1002/2015jb012028
  • NAID: 120006582475
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Presentation] Simple plate cooling model is no longer applicable to the upper mantle beneath the northwestern Pacific: Evidence from marine magnetotellurics (2017)
  • Author(s): Baba, K., N. Tada, T. Matsuno, P. Liang, R. Li, L. Zhang, H. Shimizu, N. Abe, N. Hirano, M. Ichiki, and H. Utada
  • Organizer: JpGU-AGU joint meeting 2017
  • Int'l Joint Research
• [Presentation] A three-dimensional electrical conductivity image of the mantle plume of the Society hotspot in French Polynesia (2017)
  • Author(s): Tada, N., P. Tarits, K. Baba, H. Utada, T. Kasaya, and D. Suetsug
  • Organizer: IAG-IASPEI Joint Scientific Assembly 2017
  • Int'l Joint Research
• [Presentation] Mantle transition zone beneath a normal seafloor in the northwestern Pacific: Electrical conductivity, seismic thickness, and water content (2017)
  • Author(s): Matsuno, T., D. Suetsugu, K. Baba, N. Tada, H. Shimizu, H. Shiobara, T. Isse, H. Sugioka, A. Ito, M. Obayashi, and H. Utada
  • Organizer: IAG-IASPEI Joint Scientific Assembly 2017
  • Int'l Joint Research
• [Presentation] Structure of the lithosphere-asthenosphere system in the vicinity of the Tristan da Cunha hot spot as seen by surface waves (2017)
  • Author(s): Bonadio R., W. H. Geissler, M. Ravenna, S. Lebedev, N. L. Celli, W. Jokat, M. Jegen, C. Sens-Schoenfelder, and K. Baba
  • Organizer: EGU General Assembly 2017
  • Int'l Joint Research
• [Presentation] Towards electrical resistivity imaging around outer-rise bending normal faults off the Japan trench (2017)
  • Author(s): Ichihara, H., T. Kasaya, T. Goto, K. Baba, and M. Yamano
  • Organizer: JpGU-AGU Joint meeting 2017
  • Int'l Joint Research
• [Presentation] Estimation of electrical anisotropy in the oceanic upper mantle from seafloor magnetotelluric array data (2017)
  • Author(s): Matsuno, T., K. Baba, and H. Utada
  • Organizer: JpGU-AGU Joint meeting 2017
  • Int'l Joint Research
• [Presentation] Estimation of electrical anisotropy in the oceanic upper mantle from seafloor magnetotelluric array data (2017)
  • Author(s): Matsuno, T., K. Baba, and H. Utada
  • Organizer: IAG-IASPEI Joint Scientific Assembly 201
  • Int'l Joint Research
• [Presentation] Synthetic modeling of global induction by the GAIA Sq source model (2017)
  • Author(s): Koyama, T., Y. Murata, S. Fujita, I. Fujii, K. Baba, Y. Miyoshi, H. Fujiwara, H. Jin, H. Shinagawa
  • Organizer: IAPSO-IAMAS-IAGA Joint Assembly 2017
  • Int'l Joint Research
• [Presentation] Asthenospheric temperature and lithospheric thickness beneath the Tristan da Cunha hotspot from probablilistic inversion of surface-wave dispersion data and petrological modeling (2017)
  • Author(s): Bonadio, R., W. H. Geissler, S. Lebedev, M. Ravenna, J. Fullea, N. L. Celli, W. Jokat, M. Jegen, C. Sens-Schoenfelder, and K. Baba
  • Organizer: AGU 2017 fall meeting
  • Int'l Joint Research
• [Presentation] Electrical feature at the depth of lithosphere-asthenosphere boundary beneath the petit-spot volcanic field in northwestern Pacific, (2017)
  • Author(s): Baba, K., N. Abe, N. Hirano, and M. Ichiki
  • Organizer: AGU 2017 fall meeting
  • Int'l Joint Research
• [Presentation] Sensitivity analysis of high conductivity anomalies in the upper mantle beneath the Society hotspot (2017)
  • Author(s): 多田訓子, P. Tarits, 馬場聖至, 歌田久司, 末次大輔
  • Organizer: 日本地球惑星科学連合2017年大会
• [Presentation] Estimation of the seafloor electromagnetic responses in the mixed excitation band by using Sompi Spectral Analysis (2017)
  • Author(s): Li, R., 清水久芳, 馬場聖至, 歌田久司
  • Organizer: 日本地球惑星科学連合2017年大会
• [Presentation] GAIA Sqソースモデルによるグローバル電磁誘導計算とマントル電気伝導度構造推定への応用 (2017)
  • Author(s): 小山崇夫, 村田友香, 藤田茂, 藤井郁子, 馬場聖至, 三好勉信, 藤原均, 陣英克, 品川裕之
  • Organizer: 第142回地球電磁気・地球惑星圏学会講演会
• [Presentation] 海底MTアレイデータと独立成分分析を用いたSq成分分離の試み (2017)
  • Author(s): 馬場聖至
  • Organizer: 第142回地球電磁気・地球惑星圏学会講演会
• [Presentation] 高次モードの外部磁場ソースに対する3次元不均質球体電磁誘導モデリング (2016)
  • Author(s): 小山崇夫, 清水久芳
  • Organizer: 第140回地球電磁気・地球惑星圏学会講演会
  • Place of Presentation: 九州大学（福岡県・福岡市）
  • Year and Date: 2016-11-19
• [Presentation] Marine magnetotellurics imaged no plume beneath the Tristan da Cunha hotspot in the southern Atlantic Ocean (2016)
  • Author(s): Baba, K., J. Chen, M. Sommer, H. Utada, W. Geissler, W. Jokat, and M. Jegen
  • Organizer: 23rd Electromagnetic Induction Workshop
  • Place of Presentation: Chiang Mai, Thailand
  • Year and Date: 2016-08-14
  • Int'l Joint Research
• [Presentation] Mantle transition zone beneath a normal seafloor in the northwestern Pacific: electrical conductivity, seismic thickness, and water content (2016)
  • Author(s): Matsuno, T., D. Suetsugu, H. Utada, K. Baba, N. Tada, H. Shimizu, H. Shiobara, T. Isse, H. Sugioka, A. Ito, and M. Obayashi
  • Organizer: 23rd Electromagnetic Induction Workshop
  • Place of Presentation: Chiang Mai, Thailand
  • Year and Date: 2016-08-14
  • Int'l Joint Research
• [Presentation] Estimating volatile content in oceanic upper mantle from magnetotelluric observations (2016)
  • Author(s): Baba, K
  • Organizer: Goldschmidt Conference 2016
  • Place of Presentation: パシフィコ横浜（神奈川県・横浜市）
  • Year and Date: 2016-06-26
  • Int'l Joint Research / Invited
• [Presentation] Mantle transition zone beneath a normal seafloor in the northwestern Pacific: Electrical conductivity, seismic discontinuity, and water content (2016)
  • Author(s): Matsuno, T., D. Suetsugu, H. Utada, K. Baba, N. Tada, H. Shimizu, H. Shiobara, T. Isse, H. Sugioka, and A. Ito
  • Organizer: JpGU meeting 2016
  • Place of Presentation: 幕張メッセ（千葉県・千葉市）
  • Year and Date: 2016-05-22
  • Int'l Joint Research
• [Presentation] Five years of the Normal Oceanic Mantle (NOMan) Project (2016)
  • Author(s): Utada, H., H. Kawakatsu, H. Shiobara, K. Baba, T. Isse, A. Takeo, and D. Suetsugu
  • Organizer: JpGU meeting 2016
  • Place of Presentation: 幕張メッセ（千葉県・千葉市）
  • Year and Date: 2016-05-22
  • Int'l Joint Research / Invited
• [Presentation] Possibility of anisotropic structure in electrical conductivity for the upper mantle beneath northwestern Pacific Ocean (2016)
  • Author(s): Baba, K., and H. Utada
  • Organizer: JpGU meeting 2016
  • Place of Presentation: 幕張メッセ（千葉県・千葉市）
  • Year and Date: 2016-05-22
  • Int'l Joint Research
• [Presentation] 南大西洋トリスタン・ダ・クーニャホットスポットの下にはプルームがない：電気伝導度構造からの示唆 (2016)
  • Author(s): 馬場聖至, J. Chen, 歌田久司, M. Jegen
  • Organizer: 日本地球惑星科学連合2016年大会
  • Place of Presentation: 幕張メッセ（千葉県・千葉市）
  • Year and Date: 2016-05-22
• [Presentation] Fast and memory saved 3-D forward modeling code by using the contracting integral equation (CIE) method (2016)
  • Author(s): T. Koyama
  • Organizer: Magnetotelluric 3D Inversion Workshop III
  • Place of Presentation: Bari, Italy
  • Year and Date: 2016-05-16
  • Int'l Joint Research
• [Presentation] Thermal and compositional constrains on the upper mantle beneath the northwestern Pacifc: imposed by marine magnetotelluircs (2016)
  • Author(s): Baba, K., N. Tada, T. Matsuno, H. Shimizu, L. Zhang, P. Liang, and H. Utada
  • Organizer: EGU General Assembly 2016
  • Place of Presentation: Vienna, Austria
  • Year and Date: 2016-04-17
  • Int'l Joint Research
• [Presentation] Mantle transition zone beneath a normal seafloor in the northwestern Pacific: Electrical conductivity, seismic discontinuity, and water content (2016)
  • Author(s): Matsuno, T., D. Suetsugu, H. Utada, K. Baba, N. Tada, H. Shimizu, H. Shiobara, H. Sugioka, and A. Ito
  • Organizer: EGU General Assembly 2016
  • Place of Presentation: Vienna, Austria
  • Year and Date: 2016-04-17
  • Int'l Joint Research
• [Presentation] Five years of the Normal Oceanic Mantle (NOMan) Project (2016)
  • Author(s): Utada, H, *H. Kawakatsu, H. Shiobara, K. Baba, T. Isse, D. Suetsugu, and NOMan Project team
  • Organizer: EGU General Assembly 2016
  • Place of Presentation: Vienna, Austria
  • Year and Date: 2016-04-17
  • Int'l Joint Research
• [Presentation] GAIAモデルを利用したSqの再現とその応用 (2016)
  • Author(s): 藤田茂, 藤井郁子, 三好勉信, 陣英克, 小山崇夫, 馬場聖至, 松野哲男
  • Organizer: CA研究会
  • Place of Presentation: 東京大学地震研究所（東京都文京区）
  • Year and Date: 2016-01-06
• [Presentation] 北西太平洋のふつうの海洋マントル遷移層：電気伝導度、地震波不連続面、含水量 (2016)
  • Author(s): 松野哲男, 末次大輔, 歌田久司, 馬場聖至, 多田訓子, 清水久芳, 塩原肇, 一瀬建日, 杉岡裕子, 伊藤亜妃
  • Organizer: CA研究会
  • Place of Presentation: 東京大学地震研究所（東京都文京区）
  • Year and Date: 2016-01-06
• [Presentation] The amount of water reserved in a “normal” oceanic mantle transition zone beneath the northwestern Pacific, inferred from data of coincident ocean bottom electromagnetic and seismic observations (2015)
  • Author(s): Matsuno, T., D. Suetsugu, H. Utada, K. Baba, N. Tada, H. Shimizu, H. Shiobara, T. Isse, H. Sugioka, and A. Ito
  • Organizer: AGU 2015 fall meeting
  • Place of Presentation: San Francisco, USA
  • Year and Date: 2015-12-14
  • Int'l Joint Research
• [Presentation] Normal Oceanic Mantle (NOMan) project (2015)
  • Author(s): Baba, K., N. Tada, T. Matsuno, H. Shimizu, and H. Utada
  • Organizer: 26th Schmucker-Weidelt Kolloquium fuer Elektromagnetische Tiefenforschung
  • Place of Presentation: Dassel, Germany
  • Year and Date: 2015-09-21
  • Int'l Joint Research
• [Presentation] 「ふつう」の海洋マントルの電気伝導度構造イメージング (2015)
  • Author(s): 馬場聖至, 多田訓子, 松野哲男, 梁朋飛, 張羅磊, 清水久芳, 歌田久司
  • Organizer: 日本地球惑星科学連合2015年大会
  • Place of Presentation: 幕張メッセ（千葉県千葉市）
  • Year and Date: 2015-05-24
• [Presentation] 「ふつうの海洋マントル」プロジェクトにおけるマントル遷移層電気伝導度構造の解明 (2015)
  • Author(s): 松野哲男, 歌田久司, 馬場聖至, 清水久芳, 多田訓子
  • Organizer: 日本地球惑星科学連合2015年大会
  • Place of Presentation: 幕張メッセ（千葉県千葉市）
  • Year and Date: 2015-05-24