2019 Fiscal Year Final Research Report
Subduction of oceanic plates beneath the Japanese islands and dynamics of thermal structure, water transportation, and anisotropy in the mantle wedge
| Project/Area Number |
16H04040
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Solid earth and planetary physics
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| Research Institution | Kobe University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
中島 淳一 東京工業大学, 理学院, 教授 (30361067)
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| Project Period (FY) |
2016-04-01 – 2020-03-31
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| Keywords | マントルウェッジ / 温度場 / 水輸送 / ダイナミクス |
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| Outline of Final Research Achievements |
We constructed a three-dimensional thermal convection oceanic plate subduction model in which the Pacific plate and the Philippine Sea plate are subducting simultaneously in the Kanto-Tohoku region. The temperature and the flow fields due to the interaction between the two plates were clarified, and it was shown that the intraslab earthquake occurrence region could be well explained by the dehydration region predicted from the model using the phase diagram.
We also analyzed intraslab seismicity in the Philippine Sea slab and estimated 3D heterogeneous structure in the mantle wedge of central Japan. Obtained results revealed the locations of slab dehydration and distribution of fluids and melts toward active volcanoes in central Japan, providing a better understanding of fluids transportation paths in the mantle wedge.
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| Free Research Field |
固体地球物理学
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| Academic Significance and Societal Importance of the Research Achievements |
モデルから予測された脱水域と地震活動の相関が高いという結果が得られたことは、スラブ内地震が含水鉱物の脱水と関連して発生している可能性が高いこと、予測が難しいとされていた温度構造が本研究のモデルで正確に推定できたことを意味している。
また、活火山が多く分布する中部日本において詳細な三次元地震波減衰構造を求めることで、マントルエッジにおける流体の供給経路をイメージングすることができた。また、プレート境界からの周期的な水の放出を世界で初めて観測的に実証した。
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