High-resolution estimation of three-dimensional seismic velocity structure aiming to elucidate the behavior of slab-derived fluids beneath southern Kyushu
| Project/Area Number |
16K05540
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Solid earth and planetary physics
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| Research Institution | Kyoto University |
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Principal Investigator |
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| Project Period (FY) |
2016-04-01 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2018: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2017: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2016: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
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| Keywords | 地震波走時トモグラフィ / 3次元地震波速度構造 / レシーバ関数 / 地震波速度不連続面 / スラブ起源流体 / フィリピン海スラブの形状 / 深部マグマ / 南九州 / トモグラフィ / フィリピン海スラブ / 桜島 |
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| Outline of Final Research Achievements |
In this study, the seismic velocity discontinuities and three-dimensional seismic velocity structures were estimated by receiver function analysis and seismic tomography analysis using data from linear array seismic observations independently conducted in Southern Kyushu to estimate the properties of the source area of the Hyuga-nada earthquake and the magma supply process to volcanoes such as Sakurajima and Kirishima.
Receiver function analysis shows low-velocity layers in the lower crust below the two volcanoes mentioned above. The continental Moho at the mantle wedge is obscure, indicating that the seismic velocity in the mantle is not faster than that in the lower crust. Tomographic analysis revealed a low-velocity anomaly in the vicinity of the above two volcanoes at a depth of 10 km and in the oceanic crust at a depth of 30-40 km. These features can be attributed to fluids such as slab-derived fluids and magma.
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| Academic Significance and Societal Importance of the Research Achievements |
本研究により推定された低速度異常域の分布から、南九州下に沈み込むフィリピン海プレートからマントルウェッジへの流体の供給過程が見えてきた。一つは海洋地殻の深さ40 km付近からの脱水であり、もう一つは80 km以深からの脱水である。さらに桜島火山や霧島火山を含む火山帯に沿って強い低速度異常域が深さ20 km付近に存在することも明らかになった。この成因としては、浅い部分で放出された流体の直接的な供給と、深い部分で放出され、マントルウェッジを上昇して来た流体の供給の両方が考えられる。本研究で得られたこれらの知見は、まだ未解明な点が多い下部地殻以深でのマグマの供給過程を研究するうえで非常に重要である。
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Report
(5 results)
Research Products
(9 results)
