| Project/Area Number |
16KK0092
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| Research Category |
Fund for the Promotion of Joint International Research (Fostering Joint International Research)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Natural disaster / Disaster prevention science
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| Research Institution | Ibaraki University |
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Principal Investigator |
HASEGAWA Takeshi 茨城大学, 理工学研究科(理学野), 准教授 (00574196)
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| Project Period (FY) |
2017 – 2021
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| Project Status |
Completed (Fiscal Year 2021)
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| Budget Amount *help |
¥8,970,000 (Direct Cost: ¥6,900,000、Indirect Cost: ¥2,070,000)
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| Keywords | 火山 / 巨大噴火 / カルデラ / 古地磁気 / マグマ / 岩石 / 地質 / 大規模噴火 |
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| Outline of Final Research Achievements |
The purpose of this study is to understand generation processes and risk assessment of “super (large-scale) eruption” based on comparative study of super volcanoes in New Zealand and Japan. At first, I investigated a case of "simultaneous super eruptions" reported in New Zealand. The paleomagnetic data suggest that it was not simultaneous event but there was at least 50 years time gap between the each super eruption. Next, I estimated the duration of super eruption for 10 examples in Japan and New Zealand by using paleomagnetic directions and secular variation that provides a unique quantitative assessment. The data infer that there are only 2 cases showing a short eruption duration within dozens of years. Furthermore, the 2 cases are relatively small volume (10 km3) eruptions. It could be concluded that almost super eruptions need more than tens to hundreds years from the initiation to the termination.
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| Academic Significance and Societal Importance of the Research Achievements |
本研究の成果により、これまで地質学的な根拠から過去の地球上で発生していたと考えられてきた巨大噴火の同時発生イベントは存在しないであろうことが示された。また、巨大噴火自体も一瞬（数時間や数日の単位）のできごとではなく、特に総噴出量が大きくなればなるほど、数十年あるいは数百年以上の長い時間をかけて断続的に発生するイベントとなる可能性を指摘することができる。これは、これまで普通に存在すると考えられてきた「超巨大噴火（噴出量100 km3以上）」の存在自体に疑問を投げかける重要な成果であり、将来の長期的な巨大噴火の予測や防災対策にも大きな意義を持つと考えられる。
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