Controlling processes of volcanic eruptions estimated based on chlorine mapping of volcanic rocks

• Project/Area Number: 17K14376
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Solid earth and planetary physics
• Research Institution: Hokkaido University
• Principal Investigator: Yoshimura Shumpei 北海道大学, 理学研究院, 助教 (20706436)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000); Fiscal Year 2018: ¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000); Fiscal Year 2017: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
• Keywords: マグマ / 揮発性成分 / 脱ガス / 火山噴火 / 塩素 / 火山

Outline of Final Research Achievements

Silicic magma erupts either explosively to discharge pyroclasts and high-temperature gas or non-explosively to effuse lava. However, mechanisms controlling these erupetion styles have been unclear. In this research project we have developed a new method "chlorine microscopy" to reveal the detailed gas behaviour in ascending magma. We applied this method to Mukaiyama lava and elucidated the detailed degassing processes including vesiculation, open-system gas loss, and bubble resorption.

Academic Significance and Societal Importance of the Research Achievements

火山噴火は，非常に爆発的に起こることもあれば，きわめて穏やかに進行することもある．ある噴火がどのように進展して行くかを予測することは現状では難しい．それは，噴火の仕方を決定する最重要要因である「マグマ中でのガスの振る舞い方」が全くわかっていないためである．本研究では，火山噴出物中の塩素濃度の空間分布を詳しく解析することで，地下のマグマ中でのガスの振る舞いを詳しく解読する技術を開発した．これを駆使してさまざまな噴火でのガスの振る舞いを解読し，それを噴火様式と対応付けてゆけば，やがて噴火の仕組みが次第に明らかになると期待される．

Research Products

• [Journal Article] Fingerprint of silicic magma degassing visualised through chlorine microscopy (2019)
  • Author(s): Yoshimura S. et al.
  • Journal Title: Scientific Reports Volume: 9 Pages: 786-786
  • Peer Reviewed
• [Journal Article] Fingerprint of silicic magma degassing visualised through chlorine microscopy (2019)
  • Author(s): Yoshimura, S., Kuritani, T., Matsumoto, A., Nakagawa, M.
  • Journal Title: Scientific Reports Volume: 9 Issue: 1 Pages: 1-8
  • DOI: 10.1038/s41598-018-37374-0
  • Peer Reviewed / Open Access
• [Journal Article] Chlorine diffusion in rhyolite under low-H2O conditions (2018)
  • Author(s): Shumpei Yoshimura
  • Journal Title: Chemical Geology Volume: 483 Pages: 619-630
• [Journal Article] 火山噴火を中枢制御するマグマの発泡とガス輸送の実態 (2018)
  • Author(s): 吉村俊平
  • Journal Title: 可視化情報 Volume: 38 Pages: 16-20
  • NAID: 130007638035
• [Presentation] 塩素を利用した火山噴火メカニズムの研究 (2019)
  • Author(s): 吉村俊平
  • Organizer: 日本鉱物科学会2019年年
• [Presentation] Mechanism of volatile transport from mafic to silicic magmas upon mixing (2019)
  • Author(s): Yoshimura, S. et al.
  • Organizer: JPGU2019
  • Int'l Joint Research
• [Presentation] Chlorine mapping analysis as a new tool to explore degassing processes of volatile rich silicic magma (2019)
  • Author(s): Yoshimura, S.
  • Organizer: JSPS Japanese-German graduate externship International Workshop on “Volatile Cycles”
  • Int'l Joint Research / Invited
• [Presentation] Eruption dynamics recorded in Cl distribution in glassy lava (2018)
  • Author(s): S. Yoshimura
  • Organizer: Earthquake Research Institute, University of Tokyo Joint Usage Workshop International Workshop on Pre-eruptive Magmatic Processes
• [Presentation] Chlorine mapping as a new tool to investigate the degassing processes of silicic magma (2017)
  • Author(s): S.Yoshimura,M.Nakagawa,A.Matsumoto
  • Organizer: JpGU-AGU Joint Meeting 2017
• [Presentation] 流紋岩質メルトの発泡実験と溶岩ドーム爆発条件の制約 (2017)
  • Author(s): 谷口瑞帆・吉村俊平
  • Organizer: JpGU-AGU Joint Meeting 2017
• [Presentation] 等化学ポテンシャルモデルから予想される地殻流体組成:堆積盆流体の例 (2017)
  • Author(s): 吉村俊平
  • Organizer: 日本鉱物科学会２０１７年年会
• [Book] 自然科学実験 (2019)
  • Author(s): 北海道大学自然科学実験編集委員会 編
  • Total Pages: 256
  • Publisher: 学術図書出版
  • ISBN: 9784780606904