2018 Fiscal Year Final Research Report
Preliminary evaluation of influence of magmatic process on geo-/hydro-thermal activity prior to explosive eruption using noble gas isotopes
| Project/Area Number |
16K01322
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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 |
Natural disaster / Disaster prevention science
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| Research Institution | Fukushima National College of Technology |
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Principal Investigator |
SATO KEIKO 福島工業高等専門学校, 化学・バイオ工学科, 特命准教授 (40359196)
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| Co-Investigator(Kenkyū-buntansha) |
伴 雅雄 山形大学, 理学部, 教授 (50208724)
山崎 誠子 国立研究開発法人産業技術総合研究所, 地質調査総合センター, 研究員 (90555236)
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| Research Collaborator |
Kumagai Hidenori 国立研究開発法人海洋研究開発機構, 海底資源研究開発センター (10344285)
Takebe Yoshinori 山形大学, 理学部 (40771746)
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Keywords | 希ガス / 火山噴火準備過程 / 熱水 / 湖水 / 温泉 / 火山層序 / 噴気 / 同位体 |
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| Outline of Final Research Achievements |
Noble gases have unique characteristics that they are rarely combined with other chemicals as their very stable nature. In order to expand their application for geochemical tracer, we investigated their variation compared to the volcanogeological natures of the eruption products. A crater lake water sampled from L. Okama and a fumarole gas nearby hot spring were cramped and sealed into Cu-tubing since 2016 autumn, in order to evaluate preparation of eruption. Sufficient amount of He was successfully extracted from the sampled water and transferred to mass spectrometer. He isotope compositions were slightly but significantly deviated from atmospheric composition. According to the mixing extrapolation to mantle 4He/20Ne values from the sample 3He/4He a possible contribution of subcontinental mantle helium was inferred to the crater lake water.
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| Free Research Field |
同位体地球化学、災害科学、地球惑星科学
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| Academic Significance and Societal Importance of the Research Achievements |
最近10万年程度の火山活動史が正確に編年されることは、防災の観点から極めて重要である。一方、カルデラ形成を伴うような中小規模～爆発的噴火が10万～近年にかけて見かけ上集中しているため、この範囲の放射年代を精度良く決める事は非常に困難でもある。加えて、そのような爆発的噴火の準備過程が中小規模噴火と同一の噴火様式か否か、必ずしも確かな知見は得られていない。この中で、火山岩全般への適用範囲の広いK-Ar年代と噴出物や熱水・湧水等の希ガス同位体分析から、同位体比の変遷を測定し、異常を読み解き、火山ガス放出の時間変遷と・爆発的噴火への準備過程への制約を試みる。
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