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Table 2 Minerals in the volcanic ash of the 2018–2019 eruption at Kuchinoerabujima Volcano

From: Influence of hydrothermal recharge on the evolution of eruption styles and hazards during the 2018–2019 activity at Kuchinoerabujima Volcano, Japan

Sample ID Date of eruption Pl Qtz Cri Tri Alu Gyp Anh Pyr Silica/Pl sulfate/Pl sulfide/Pl
18-Keb02-4 Oct. 21, 2018 *** * *** * ** n.p * n.p 0.5 0.2 0.0
18-Keb03-1 Oct. 22, 2018
Oct. 25, 2019
*** * *** * * n.p *** n.p 1.0 0.7 0.1
18-Keb07-2 Nov. 5, 2018 *** n.p *** * ** n.p ** n.p 0.6 0.3 0.0
18-Keb09 Nov. 12, 2018 *** n.p *** * ** n.p * n.p 1.0 0.5 0.1
18-Keb12-1 Nov. 20 and 21, 2018 *** * *** * * n.p * n.p 0.9 0.4 0.1
18-Keb15 Dec. 6, 2018 *** * *** * * ** n.p n.p 1.1 0.6 0.1
18-Keb17 Dec. 18, 2018 ** * *** * ** ** *** * 3.3 8.1 0.5
18-Keb19-1 Dec. 28, 2018 *** * *** *** ** * *** n.p 1.4 0.7 0.1
19-Keb03-3 Jan. 17, 2019 *** n.p *** *** ** *** *** * 2.0 6.1 0.4
19-Keb06 Jan. 20, 2019 *** * *** * ** *** *** ** 1.9 9.0 0.5
19-Keb09-2 Jan. 29, 2019 *** n.p *** * *** * *** n.p 0.9 1.1 0.1
  1. The intensities of X-ray peaks in the XRD analysis are shown as: ***Intense; **Weak; *Minor; and n.p. no peaks were determined
  2. Mineral abbreviations; Pl plagioclase including anorthite and albite, Trd tridymite, Crs cristobalite, Qtz quartz, Gp gypsum, Anh anhydrite, Alu alunite and natro-alunite (minamiite); and Py pyrite
  3. The peak intensities of alunite basically used K-alunite and those with are natro-alunite (minamiite)
  4. Ratio of peak value refers to the total peak intensity of maximum peaks of silica minerals of tridymite, cristobalite, and quartz (silica/Pl); sulfate of gypsum, anhydrite, and alunite (sulfate/Pl); and sulfide of pyrite (sulfide/Pl), divided by maximum peak intensity of plagioclase (Pl), respectively