JDR Vol.14 No.7 pp. 991-995
doi: 10.20965/jdr.2019.p0991


Constituent Mineral and Water-Soluble Components of Volcanic Ash from the 2018 Eruption of Mt. Motoshirane of Kusatsu-Shirane Volcano, Japan

Muga Yaguchi*,†, Takeshi Ohba**, Nozomi Numanami**, and Ryohei Kawaguchi*

*Volcanology Research Department, Meteorological Research Institute, Japan Meteorological Agency
1-1 Nagamine, Tsukuba, Ibaraki 305-0052, Japan

Corresponding author

**Department of Chemistry, School of Science, Tokai University, Kanagawa, Japan

April 26, 2019
June 19, 2019
October 1, 2019
Mt. Motoshirane, phreatic eruption, volcanic ash, hydrothermal mineral, water-soluble component

Constituent minerals and water-soluble components of the volcanic ash discharged from the eruption of Mt. Motoshirane on January 23, 2018, were analyzed to investigate the source environment of this eruption. The ash sample included quartz, plagioclase, cristobalite, pyrite, alunite, kaolinite, and pyrophyllite; its mineral assemblage suggests that a high-temperature acid alteration zone had been formed in the volcanic edifice of Mt. Motoshirane. The presence of pyrophyllite in the ash sample indicates that the explosion of this eruption took place at a depth reaching the basement rocks of Mt. Motoshirane. Further, the adhesion amount of water-soluble components detected from the ash sample is smaller than that in the ashes from the 1982 eruption of Mt. Shirane, indicating that the ash discharge of the 2018 eruption of Mt. Motoshirane took place in a condition in which the degree of involvement of the liquid phase was relatively small.

Cite this article as:
M. Yaguchi, T. Ohba, N. Numanami, and R. Kawaguchi, “Constituent Mineral and Water-Soluble Components of Volcanic Ash from the 2018 Eruption of Mt. Motoshirane of Kusatsu-Shirane Volcano, Japan,” J. Disaster Res., Vol.14 No.7, pp. 991-995, 2019.
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