Constructing a model of outgassing from basaltic magma based on observations and experiments

2023 Fiscal Year Final Research Report

• Project/Area Number: 17KK0092
• Research Category: Fund for the Promotion of Joint International Research (Fostering Joint International Research)
• Allocation Type: Multi-year Fund
• Research Field: Solid earth and planetary physics
• Research Institution: Nagoya University (2020-2023); Hiroshima University (2017-2019)
• Principal Investigator: Namiki Atsuko 名古屋大学, 環境学研究科, 准教授 (20450653)
• Project Period (FY): 2018 – 2023
• Keywords: マグマ / 気泡 / 熔岩 / 結晶 / ハワイ / キラウエア火山

Outline of Final Research Achievements

This study consists of the following three parts. (1) observations of the 2018 lower East Rift Zone eruption of Kilauea Volcano, Hawaii, (2) experiments on lava flows containing bubbles at the Lamont-Doherty Earth Observatory (LDEO), and (3) a study of the onset of magma rise.
For (1), I visited Hawaii in 2018 and had the rare opportunity to observe the Lower East Rift Zone eruption that occurred that year. Based on infrared images of lava fountains observed during this eruption, we estimated that fragmentation is caused by a temperature drop due to the rapid expansion of volcanic gases, which cools the magma surface. For (2), I visited the LDEO in 2019 and conducted experiments on lava flows containing bubbles. The lava observed in (1) had a high volume fraction of bubbles, and the experiment was designed to simulate this situation. For (3), we co-authored a review paper summarizing the basic concepts in this field.

Free Research Field

火山学

Academic Significance and Societal Importance of the Research Achievements

（１）これまであまり理解の進んでいなかった玄武岩質熔岩の破砕プロセスを観測・物質科学的観察・及び理論的見積もりから明らかにした。これにより玄武岩質熔岩の爆発的噴火において重要なプロセスの理解への道が開けた。2018年ハワイ島の噴火は日本でも度々報道された規模の大きい噴火であった。この噴火の観測に参加し、学術的価値の高い論文を執筆できた事が社会的な意義だといえる。
（２）熔岩流における気泡の効果を明らかにした事に学術的な意義がある。
（３）噴火が始まる条件は噴火予測において最も重要な知見である。この問題に関する総説を執筆した事は学術的にも社会的にも大きな意義がある。