Past oceanic plate motion based on seismological analysis

• Project/Area Number: 16K05533
• 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: ISSE Takehi 東京大学, 地震研究所, 助教 (60359180)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000); Fiscal Year 2018: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2017: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2016: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
• Keywords: 海洋プレート構造 / 海洋マントル構造 / 地球・惑星内部構造 / 表面波トモグラフィー / 方位異方性構造 / プレート運動

Outline of Final Research Achievements

We analyzed seismic waveform data recorded by land seismic stations and ocean bottom broadband seismometers in the Pacific Ocean, and obtained the upper mantle shear wave velocity structure in the Pacific region. Fast axis of the azimuthal anisotropic structure of shear wave was consistent with the direction of current plate motion in the deep part, but the shallow part structure is complicated. To estimate the past plate motion direction from the azimuthal anisotropic structure, it is necessary to remove the anomalous area that deviates from the plate growth in the analysis area. We performed analysis combining the velocity structure obtained and the temperature structure of the oceanic mantle, and clarified anomalous regions that can not be explained by the plate growth model.

Academic Significance and Societal Importance of the Research Achievements

太平洋地域の上部マントル地震波速度構造はこれまで陸上定常地震観測網のみから推定されており，推定された構造の空間解像度に限界があった．本研究は陸上観測網に加え，日本・アメリカの研究グループにより実施された臨時海底広帯域地震観測記録を用いて太平洋の海洋プレート構造を解析した最初の研究である．またプレート成長モデルで説明できない領域の解明は地球成長史の解明に寄与する知見である．

Research Products

• [Journal Article] Surface wave tomography for the Pacific Ocean incorporating seafloor seismic observations and plate thermal evolution (2019)
  • Author(s): Isse Takehi、Kawakatsu Hitoshi、Yoshizawa Kazunori、Takeo Akiko、Shiobara Hajime、Sugioka Hiroko、Ito Aki、Suetsugu Daisuke、Reymond Dominique
  • Journal Title: Earth and Planetary Science Letters Volume: 510 Pages: 116-130
  • DOI: 10.1016/j.epsl.2018.12.033
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] Surface wave tomography for the Pacific Ocean incorporating seafloor seismic observations and its age-dependence (2018)
  • Author(s): T. Isse, H. Kawakatsu, K. Yoshizawa, A. Takeo, H. Shiobara, H. Sugioka, A. Ito, D. Suetsugu, D. Reymond
  • Organizer: AGU fall meeting 2018
  • Int'l Joint Research
• [Presentation] Shear wave upper mantle structure beneath the Ontong Java Plateau (2018)
  • Author(s): T. Isse, D. Suetsugu, H. Shiobara, H. Sugioka, A. Ito, Y. Ishihara, S. Tanaka, M. Obayashi, T. Tonegawa, J. Yoshimitsu, T. Kobayashi
  • Organizer: Japan Geoscience Union meeting 2018
• [Presentation] Upper mantle structure beneath the Pacific Ocean revealed from seafloor and land broadband seismic observations (2018)
  • Author(s): T. Isse, H. Kawakatsu, K. Yoshizawa, A. Takeo, H. Shiobara, H. Sugioka, A. Ito, D. Suetsugu
  • Organizer: Japan Geoscience Union meeting 2018
• [Presentation] Upper mantle structure beneath the Pacific Ocean revealed by land and seafloor broadband observations (2017)
  • Author(s): T. Isse, H. Shiobara, K. Yoshizawa, H. Kawakatsu, H. Sugioka, A. Ito, D. Suetsugu, H. Utada
  • Organizer: IAG-IASPEI 2017
  • Int'l Joint Research
• [Presentation] Upper mantle structure beneath the Pacific Ocean revealed by land and seafloor broadband observations (2017)
  • Author(s): T. Isse, H. Shiobara, K. Yoshizawa, H. Kawakatsu, H. Sugioka, A. Ito, D. Suetsugu, H. Utada
  • Organizer: JpGU-AGU joint meeting 2017
  • Int'l Joint Research
• [Presentation] Upper mantle structure beneath the Pacific Ocean revealed by land and seafloor broadband observations (2017)
  • Author(s): T. Isse, H. Shiobara, K. Yoshizawa, H. Kawakatsu, H. Sugioka, A. Ito, D. Suetsugu, H. Utada
  • Organizer: 2017 OBS symposium
  • Int'l Joint Research
• [Presentation] 広帯域海底地震観測記録を用いた太平洋上部マントル3次元S波速度構造 (2016)
  • Author(s): 一瀬建日・塩原肇・吉澤和範・杉岡裕子・伊藤亜妃・末次大輔
  • Organizer: 日本地震学会2016年度秋季大会
  • Place of Presentation: 名古屋国際会議場（愛知県・名古屋市）
  • Year and Date: 2016-10-05
• [Presentation] Upper mantle structure of the Pacific and Philippine Sea plates revealed by seafloor seismic array observations (2016)
  • Author(s): T. Isse. H. Shiobara, D. Suetsugu, H. Sugioka, A. Ito
  • Organizer: EGU General Assembly 2016
  • Place of Presentation: ACV (Vienna, Austria)
  • Year and Date: 2016-04-21
  • Int'l Joint Research
• [Funded Workshop] EGU General Assembly 2016 (2016)
  • Place of Presentation: ACV (Vienna, Austria)
  • Year and Date: 2016-04-17