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.
Data files:
  1. [1] Geographical Survey Institute of Japan, 2019, (in Japanese) [accessed April 15, 2019]
  2. [2] The Joint Research Team for ash fall in Kusatsu-Shirane 2018 eruption, “Ash fall distribution of Jan. 23, 2018 eruption in Kusatsu-Shirane Volcano,” Report of the Coordinating Committee for Prediction of Volcanic Eruptions, Vol.129, pp. 87-91, 2018 (in Japanese).
  3. [3] T. Ohba, J. Hirabayashi, and K. Nogami, “D/H and 18O/16O ratios of water in the crater lake at Kusatsu-Shirane volcano, Japan,” J. Volcanol. Geotherm. Res., Vol.97, No.1-4, pp. 329-346, doi:10.1016/S0377-0273(99)00169-9, 2000.
  4. [4] T. Ohba, J. Hirabayashi, and K. Nogami, “Temporal changes in the chemistry of lake water within Yugama Crater, Kusatsu-Shirane Volcano, Japan: Implications for the evolution of the magmatic hydrothermal system,” J. Volcanol. Geotherm. Res., Vol.178, No.2, pp. 131-144, doi:10.1016/j.jvolgeores.2008.06.015, 2008.
  5. [5] M. Yaguchi, T. Ohba, and M. Sago, “The Nature and Source of the Volcanic Ash during the 2015 Small Phreatic Eruption at Hakone Volcano, Central Japan,” Geochem. J., Vol.53, pp. 209-217, doi:10.2343/geochemj.2.0560, 2019.
  6. [6] T. Ohba, “Volcanic hydrothermal system of Mt. Kusatsu-Shirane, Japan,” T. Kagiyama (Ed.), “Volcanic Structure in the Shallow Part and Volcanic Fluid,” Disaster Prevention Res. Inst., Kyoto Univ., pp. 161-168, 2001 (in Japanese).
  7. [7] Y. Katabuchi, T. Ohba, J. Hirabayashi, K. Nogami, M. Ohwada, and S. Mizuhashi, “Fumarolic and mofette gases of Kusatsu Shirane volcano,” Chikyu Monthly, No.39, pp. 46-51, 2002 (in Japanese).
  8. [8] T. Ohba and Y. Kitade, “Subvolcanic hydrothermal systems: Implications from hydrothermal minerals in hydrovolcanic ash,” J. Volcanol. Geotherm. Res., Vol.145, No.3-4, pp. 249-262, doi:10.1016/j.jvolgeores.2005.02.002, 2005.
  9. [9] K. Kazahaya, J. Hirabayashi, H. Mori, M. Odai, Y. Nakahori, K. Nogami, S. Nakada, H. Shinohara, and K. Uto, “Volcanic Gas Study of the 2000 Miyakejima Volcanic Activity: Degassing Environment Deduced from Adhered Gas Component on Ash and SO2 Emission Rate,” J. Geography, Vol.110, No.2, pp. 271-279, doi:10.5026/jgeography.110.2_271, 2001 (in Japanese with English abstract).
  10. [10] N. C. White and J. W. Hedenquist, “Epithermal gold deposits: styles, characteristics and exploration,” Soc. Econ. Geol. Newsl., No.23, pp. 1, 9-13, 1995.
  11. [11] J. J. Hemley, J. W. Montoya, J. W. Marinenko, and R. W. Luce, “Equilibria in the system Al2O3-SiO2-H2O and some general implications for alteration/mineralization processes,” Econ. Geol., Vol.75, No.2, pp. 210-228, doi:10.2113/gsecongeo.75.2.210, 1980.
  12. [12] M. Kurosaki, J. Osaka, and T. Matsuda, “Clay Minerals in the Volcanic Ejectas from Kusatsu-Shirane Volcano and the Style of Eruption,” J. Mineral. Soc. Japan, Vol.19, Issue Special, pp. 87-91, doi:10.2465/gkk1952.19.Special_87, 1990 (in Japanese with English abstract).
  13. [13] Y. Hayakawa, “Geology of Kusatsu-Shirane Volcano,” J. Geol. Soc. Japan, Vol.89, No.9, pp. 511-525, doi:10.5575/geosoc.89.511, 1983 (in Japanese with English abstract).
  14. [14] J. Hirabayashi, “Change of chemical composition of volcanic gas and volcanic activity,” Dr.Sci. Thesis, Tokyo Institute of Technology, 190pp., 1984 (in Japanese).
  15. [15] A. Terada, W. Kanda, Y. Ogawa, H. Aoyama, M. Yamamoto, T. Tsutsui, T. Ohkura, and R. Noguchi, “The phreatic eruption on 23 January 2018 at Mt. Moto-Shirane of Kusatsu-Shirane volcano, Japan: geophysical observations and implications,” Proc. of Japan Geosci. Union Meet. 2018, SVC41-37, 2018.

*This site is desgined based on HTML5 and CSS3 for modern browsers, e.g. Chrome, Firefox, Safari, Edge, IE9,10,11, Opera.

Last updated on Dec. 05, 2019