Experimental study of an instantaneous volcanic eruption

2022 Fiscal Year Final Research Report

• Project/Area Number: 17KK0085
• Research Category: Fund for the Promotion of Joint International Research (Fostering Joint International Research)
• Allocation Type: Multi-year Fund
• Research Field: Natural disaster / Disaster prevention science
• Research Institution: The University of Tokyo
• Principal Investigator: SUZUKI YUJIRO 東京大学, 地震研究所, 准教授 (30392939)
• Project Period (FY): 2018 – 2022
• Keywords: 火山噴火 / 爆発噴火 / 流体実験 / 火山防災 / 噴煙

Outline of Final Research Achievements

In order to understand the plume dynamics of instantaneous volcanic eruptions called Vulcanian eruptions, we developed a fluid experiment apparatus that simulates a Vulcanian eruption and explored the relationship between injection conditions and final altitude. Comparing the results of laboratory experiments with those of numerical simulations, we observed that the morphology changes from a flow with a vortex ring structure to a starting forced plume and a turbulent plume, depending on the duration of injection time. By introducing a new scaling with respect to the eruption duration, the final altitude was found to vary continuously. Furthermore, it was suggested that laboratory experiments and actual Vulcanian eruptions behave more as Starting forced plumes and turbulent plumes than as thermals.

Free Research Field

火山物理学

Academic Significance and Societal Importance of the Research Achievements

現在も活発に噴火している桜島火山やその他国内の多くの火山では、ブルカノ式噴火と呼ばれる瞬間的な爆発噴火の頻度が高い。そのような噴火で噴煙がどの高度まで上がり、そこから火山灰が拡散されるかは防災上非常な問題である。本課題の研究成果は、噴火条件と噴煙高度の関係が連続噴火のものとは異なることを示し、学術的に新たな知見となる。また、本研究の成果を火山灰輸送のモデルに組み込むことで、火山灰分布に関する精度の高いハザードマップを作成できると期待される。