2023 Fiscal Year Final Research Report
Experimental observational study on high temperature groundwater release from shallow ground
| Project/Area Number |
21K18784
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| Research Category |
Grant-in-Aid for Challenging Research (Exploratory)
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| Allocation Type | Multi-year Fund |
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| Review Section |
Medium-sized Section 25:Social systems engineering, safety engineering, disaster prevention engineering, and related fields
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| Research Institution | Hokkaido University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
西村 太志 東北大学, 理学研究科, 教授 (40222187)
田中 良 北海道大学, 理学研究院, 助教 (30804926)
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| Project Period (FY) |
2021-07-09 – 2024-03-31
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| Keywords | 間歇泉 / 熱水流動 / 地下水 / 多項目同時観測 / 熱輸送効率 / 表面現象 / 噴気活動 |
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| Outline of Final Research Achievements |
The goal of this study is understanding the physical background of various hydrothermal flow patterns in the shallow subsurface. To achieve the goal, we mainly focused on field observation and numerical simulation of decompression-boiling Geyser (Shikabe Geyser), which has characteristics intermediate between those of hot spring wells and steaming wells. Our study revealed that an excess supply of hydrothermal fluid from the aquifer to the conduit occurs during the eruption phase of the geyser, and that carbon dioxide gas in the hydrothermal fluid contributes to the geyser eruption. Numerical experiments using the hydrothermal flow simulator T2Well/ECO2N reproduced the cyclic eruption and provided new insights into the contribution of carbon dioxide gas and the physical processes in the conduit related to the start/stop of eruption.
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| Free Research Field |
火山物理学・地震学
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| Academic Significance and Societal Importance of the Research Achievements |
間歇泉は全世界でも1000未満と希少で，国内ではその多くが観光資源として活用されているが，開発や気候変動などの環境の変化によって周期的噴出が止まってしまうなどの問題がしばしば発生している．本研究では，減圧沸騰型の間歇泉における噴出中の孔内映像撮影に初めて成功し噴出メカニズムの理解を深めるとともに，間歇泉として振る舞う場の水理パラメータの推定を行った．得られた知見は，希少な資源である間歇泉を保護するためには極めて重要で，本研究で観測調査対象としたしかべ間歇泉以外にも広く応用できるという点で，社会的な意義も大きい．
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