JpGU-AGU Joint Meeting 2017

Presentation information

[JJ] Oral

S (Solid Earth Sciences) » S-VC Volcanology

[S-VC50] [JJ] Volcanic and igneous activities, and these long-term forecasting

Sat. May 20, 2017 10:45 AM - 12:15 PM A04 (Tokyo Bay Makuhari Hall)

convener:Teruki Oikawa(Institute of Earthquake and Volcano Geology, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology), Takeshi Hasegawa(Department of Earth Sciences, College of Science, Ibaraki University), Daisuke MIURA(Geosphere Sciences, Civil Engineering Research Laboratory, Central Research Institute of Electric Power Industry), Nobuo Geshi(Geological Survey of Japan, The National Institute of Advanced Industrial Science and Technology), Chairperson:Akiko Matsumoto(Graduate School of Science, Hokkaido University)

10:45 AM - 11:00 AM

[SVC50-07] Eruption event of Asama-Maekake volcano and the trial proposal of probabilistic event tree of its eruptive sequence

*Masaki Takahashi1, Maya Yasui1, Mitsuhiro Nakagawa2, Minoru Takeo3 (1.Department of Earth and Environmental Sciences, College of Humanities and Sciences, Nihon University, 2.Graduate School of Science, Hokkaido University, 3.Earthquake Research Institute, University of Tokyo)

Keywords:Asama volcano, eruption, event tree of eruption

The eruption event of Asama-Maekake volcano consists of four types: (1) small scale single eruption (phreatic and phreato-magmatic ), (2) intermediate scale single eruption (Vulcanian and Strombolian), (3) continuously eruptive stage (phreatic, phreato-magmatic, Vulcanian and Strombolian), and (4) large scale eruption (sub-Plinian or Plinian). A single eruption event occurs after a dormant interval of more than two years. In a continuously eruptive stage, eruptions continue for more than four years including an intercalating dormant stage of less than one year. A trial probabilistic event tree of eruptive sequence is proposed based on eruption events since 1527AD. The event tree begins with a magma intrusion detected by crustal deformation and volcanic earthquakes. The magma intrusion branches off to “no eruption” (67% probability) and “eruption” (33%). The “no eruption” event ends there. The “eruption” branches off to the “small scale eruption” (22%) and the “intermediate scale eruption” (78%). The “small scale eruption” ends there. The “intermediate scale eruption” branches off to the “continuously eruptive stage” (30%) and the “single eruption” (70%). The “continuously eruptive stage” ends there. The “single eruption” branches off to the intermediate scale eruption which ends there (88%) and the intermediate scale eruption which shifts to the “large scale eruption” (12%). The probability of occurrence of “large scale eruption” after a magma intrusion event is about 2%.