Study on fluid injection beneath the volcanic lake at the Nakadake 1st crater of Aso Volcano - aiming to understand future phreatic explosions

• Project/Area Number: 25870352
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Natural disaster / Disaster prevention science; Solid earth and planetary physics
• Research Institution: Kyoto University
• Principal Investigator: Akihiko Yokoo 京都大学, 理学(系)研究科(研究院), 助教 (70420403)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Project Status: Completed (Fiscal Year 2015)
• Budget Amount: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2015: ¥260,000 (Direct Cost: ¥200,000、Indirect Cost: ¥60,000); Fiscal Year 2014: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000); Fiscal Year 2013: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
• Keywords: 阿蘇火山 / 中岳第一火口 / 湯だまり / 土砂噴出 / 水蒸気爆発 / 火山噴火 / 連続微動 / 阿蘇山 / 噴火 / 火山 / 防災

Outline of Final Research Achievements

Volcanic activity of the Nakadake 1st crater of Aso volcano has increased since 2013 immediately after this project was started. Volcanic lake at the crater has been disappeared and then new active vent was opened inside the crater in January 2014. On 25 November 2014, magmatic eruptions started after c.a. 20 years dormancy. So as to satisfy an extreme objective of this project - understanding and evaluating of future phreatic explosions - several kinds of analysis on seismo-acoustic signals were investigated. From the analysis of high-frequency continuous tremor, final section of the pathway of volcanic fluids toward crater bottom was revealed. Monochromatic infrasound tremor with the ~0.5 Hz peak was identified by a new network of infrasound sensors. Source process of this signal was considered as the Helmholtz resonance inside the conduit.

Research Products

• [Journal Article] 2014年11月から始まった阿蘇火山中岳第一火口の噴火活動 (2015)
  • Author(s): 横尾亮彦・宮縁育夫
  • Journal Title: 火山 Volume: 60 Pages: 275-278
  • NAID: 110009976000
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Acoustic source inversion to estimate volume flux from volcanic explosions (2015)
  • Author(s): Kim, K., Fee, D., Yokoo, A., and Lees, J.M.
  • Journal Title: Geophysical Research Letters Volume: 42 Issue: 13 Pages: 5243-5249
  • DOI: 10.1002/2015gl064466
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Dual infrasound sources from a Vulcanian eruption of Sakurajima volcano, inferred from cross-array observation (2014)
  • Author(s): Yokoo, A., Suzuki, Y.J., and Iguchi, M.
  • Journal Title: Seismological Research Letter Volume: 85 Pages: 1212-1222
  • Peer Reviewed
• [Journal Article] Network-based evaluation of the infrasonic source location at Sakurajima Volcano (2014)
  • Author(s): McKee, K., Fee, D., Rowell, C., and Yokoo, A.
  • Journal Title: Seismological Research Letter Volume: 85 Pages: 1200-1211
  • Peer Reviewed
• [Journal Article] Introduction to an open communitiy infrasound dataset from the actively erupting Sakurajima Volcano (2014)
  • Author(s): Fee, D., Yokoo, A., and Johnson, J.B.
  • Journal Title: Seismological Research Letter Volume: 85 Pages: 1151-1162
  • Peer Reviewed
• [Journal Article] Estimation of exit velocity of volcanic plume from analysis of vortex structures (2014)
  • Author(s): H. Suwa, Y. J. Suzuki, A. Yokoo
  • Journal Title: Earth and Planetary Science Letters Volume: 385 Pages: 154-161
  • DOI: 10.1016/j.epsl.2013.10.032
  • Peer Reviewed
• [Journal Article] Development of an automatic volcanic ash sampling apparatus for active volcanoes (2013)
  • Author(s): Shimano, T., Nishimura, T., Chiga, N., Shibasaki, Y., Iguchi, M., Miki, D., and Yokoo, A.
  • Journal Title: Bulletin of Volcanology Volume: 75 Issue: 12 Pages: 773-773
  • DOI: 10.1007/s00445-013-0773-7
  • Peer Reviewed
• [Journal Article] Switching from seismic to seismo-acoustic harmonic tremor at a transition of eruptive activity during the Shinmoe-dake 2011 eruption (2013)
  • Author(s): Ichihara, M., J.J.Lyons, and A. Yokoo
  • Journal Title: Earth Planet Space Volume: 65 Issue: 6 Pages: 633-643
  • DOI: 10.5047/eps.2013.05.003
  • NAID: 10031193475
  • Peer Reviewed
• [Presentation] Analysis of fumarole acoustics at Aso volcano, Japan (2015)
  • Author(s): McKee, K. Yokoo, A., Fee, D., Huang, Y.C., Yoshikawa, S., Utsugi, M., Minami, T., and Ohkura, T.
  • Organizer: American Geophysical Union Fall Meeting
  • Place of Presentation: San Francisco, USA
  • Year and Date: 2015-12-14
  • Int'l Joint Research
• [Presentation] 阿蘇火山2014-2015年噴火活動の概要について (2015)
  • Author(s): 大倉敬宏・宇津木充・横尾亮彦・吉川慎・井上寛之・鍵山恒臣
  • Organizer: 日本地球惑星科学連合連合大会2015年大会
  • Place of Presentation: 幕張メッセ国際会議場
  • Year and Date: 2015-05-22
• [Presentation] 阿蘇火山中岳2014~2015年噴火の推移と噴出物(速報) (2015)
  • Author(s): 宮縁育夫・下司信夫・横尾亮彦
  • Organizer: 日本地球惑星科学連合連合大会2015年大会
  • Place of Presentation: 幕張メッセ国際会議場
  • Year and Date: 2015-05-22
• [Presentation] 阿蘇火山の火口湖活動から噴火への推移に伴う火山ガス組成変化 (2015)
  • Author(s): 篠原宏志・下司信夫・横尾亮彦・風早竜之介
  • Organizer: 日本地球惑星科学連合連合大会2015年大会
  • Place of Presentation: 幕張メッセ国際会議場
  • Year and Date: 2015-05-22
• [Presentation] 阿蘇火山における連続微動の発生位置推定 (2015)
  • Author(s): 市村美沙・横尾亮彦・鍵山恒臣・大倉敬宏・吉川慎・井上寛之
  • Organizer: 日本地球惑星科学連合連合大会2015年大会
  • Place of Presentation: 幕張メッセ国際会議場
  • Year and Date: 2015-05-22
• [Presentation] 2014年阿蘇火山噴火に伴う電磁気観測の結果について (2015)
  • Author(s): 宇津木充・大倉敬宏・横尾亮彦・鍵山恒臣
  • Organizer: 日本地球惑星科学連合連合大会2015年大会
  • Place of Presentation: 幕張メッセ国際会議場
  • Year and Date: 2015-05-22
• [Presentation] 阿蘇中岳第一火口における熱水流入過程 (2013)
  • Author(s): 横尾亮彦
  • Organizer: 地球惑星科学連合連合大会2013年大会
  • Place of Presentation: 千葉県幕張市
• [Presentation] Fluid injections at a crater lake of Aso volcano (2013)
  • Author(s): Yokoo, A.
  • Organizer: IAVCEI 2013 Scientific Assembly
  • Place of Presentation: Kagoshima, Japan