Numerical study of dynamics of pyroclastic flows using shallow-water and eruption-cloud models
| Project/Area Number |
17H02949
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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 | The University of Tokyo |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
鈴木 雄治郎 東京大学, 地震研究所, 准教授 (30392939)
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| Project Period (FY) |
2017-04-01 – 2021-03-31
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| Project Status |
Completed (Fiscal Year 2021)
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| Budget Amount *help |
¥16,640,000 (Direct Cost: ¥12,800,000、Indirect Cost: ¥3,840,000)
Fiscal Year 2020: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2019: ¥6,760,000 (Direct Cost: ¥5,200,000、Indirect Cost: ¥1,560,000)
Fiscal Year 2018: ¥6,890,000 (Direct Cost: ¥5,300,000、Indirect Cost: ¥1,590,000)
Fiscal Year 2017: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
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| Keywords | 火砕流 / 数値計算 / 浅水波モデル / 流体力学 / 重力流 |
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| Outline of Final Research Achievements |
During explosive volcanic eruptions, a mixture of pyroclasts and gas is ejected from the volcanic vent, and can flow on the ground surface as a pyroclastic density current (PDC). PDCs are generally stratified with respect to particle concentration and are composed of two layers: the upper dilute layer and the lower dense layer. The dynamics of these two layers are controlled by various physical processes with different length scales. The upper dilute layer is affected by particle settling, thermal expansion of entrained air, and resistance at the flow front, whereas the lower dense layer is controlled by friction, deposition, and erosion at the base.
We developed a two-layer PDC model where an eruption-cloud model is applied to the upper dilute layer and a depth-averaged model to the lower dense layer. The new model enables us to investigate the complex effects of volcanological factors (e.g., topographic effects as well as eruption conditions) on the run-out distances of PDCs.
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| Academic Significance and Societal Importance of the Research Achievements |
火山噴火で発生する火砕流のダイナミクスについては，最大到達距離の決定要因をはじめとする，学術上・防災上重要な基本的問題が解明されていない．これらの基本的問題が解決困難であった理由は，火砕流のダイナミクスが大気の取り込みや堆積作用など，長さスケールの異なる様々な物理過程の影響を受けることにある．本研究は，長さスケールの異なる現象を同時に扱う数値モデル（「二層浅水波モデル」および「2D浅水波・3D噴煙結合モデル」）を新たに開発し，それらを用いて火砕流の到達距離や堆積物の分布範囲・性質を支配する要因を系統的に調べた点に意義がある．
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Report
(5 results)
Research Products
(27 results)
