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Nature and origin of volcanic ash in the 2000 eruption of Usu volcano, southwestern Hokkaido, Japan
Earth, Planets and Space volume 54, pages993–998(2002)
Usu volcano, one of the most active volcanoes in Japan, erupted at regular intervals of ca. 30 years during the 1900s. The 2000 eruption took place on March 31 following 23 years of dormancy. An increase in seismic activity and remarkable ground deformation preceded the eruption. Many small-scale craters were successively formed in two areas at the foot of the volcano and ash was ejected intermittently from them. Ten samples out of the 2000 ash collected around the volcano during half a year were analyzed. They were depleted in SiO2 but enriched in FeO compared with the essential ejecta of the five major historic eruptions and all were highly altered as a whole. XRD analysis revealed smectite as a major clay mineral in the ash and kaolin as a minor one. The clay mineral assemblage and the trend of change in chemical composition of the 2000 ash are quite similar to those of the 1977–1978 ash. No temporal changes in chemical composition and clay mineral assemblage of the 2000 ash were detected. The percentages of the LOI and the relative proportions of SiO2 in the ashes and the essential ejecta showed a linear correlation. These results indicate that the constituents of the 2000 ash were alteration products of the volcaniclastics of the historic eruptions in the subsurface.
Hirabayashi, J., T. Ohba, and K. Nogami, Chemical Composition of Volcanic Gases Associated with the 1991–1992 Activity of Shinmoe-dake, Kirishima Volcanoes, Japan, Bull. Volcanol. Soc. Japan, 41, 263–267, 1996 (in Japanese).
Ishikawa, T., Formation and change of Toya Hot Spring, BUTSURI-TANKO (GEOPHYSICAL EXPLORATION), 16, 27–37, 1963 (in Japanese with English abstract).
Katsui, Y., Y. Oba, K. Onuma, T. Suzuki, Y. Kondo, T. Watanabe, K. Niida, T. Uda, S. Hagiwara, T. Nagao, J. Nishikawa, M. Yamamoto, Y. Ikeda, H. Katagawa, N. Tsuchiya, M. Shirahase, S. Nemoto, S. Yokoyama, T. Soya, T. Fujita, K. Inaba, and K. Koide, Preliminary report of the 1977 eruption of Usu Volcano, J. Fac. Sci. Hokkaido Univ., Ser. IV, 18, 385–408, 1978.
Kondo, Y., T. Fujitani, Y. Katsui, and K. Niida, Nature of the 1977–1978 Volcanic ash from Usu Volcano, Hokkaido, Japan, Bull. Volcanol. Soc. Japan, 24, 223–238, 1979 (in Japanese with English abstract).
Matsuo, S., M. Kusakabe, H. Chiba, H. Ushiki, J. Ossaka, J. Hirabayashi, T. Abiko, K. Notsu, T. Ozawa, S. Aramaki, K. Sato, T. Hayashi, J. Sato, and N. Fujii, Geochemical Study on Ground Water, Thermal Water and Ash Fall Collected Immdiately after the 1977 Eruption of the Usu Volcano, Japan, Bull. Volcanol. Soc. Japan, 22, 201–220, 1977 (in Japanese with English abstract).
Mori, Y. H. and T. Ui, Crustal Deformation and Eruptic Activities of Mt. Usu in 2000, J. JSNDS, 19-3, 383–390, 2000 (in Japanese with English abstract).
Nogami, K., J. Hirabayashi, T. Ohba, and Y. Yoshiike, The 1997 phreatic eruption of Akita-Yakeyama volcano, northwest Japan: Insight into the hydrothermal processes, Earth Planets Space, 52, 229–236, 2000.
Okada, H., H. Mori, and H. Oshima, Bases of Successful Prediction of the Eruption of Mt. Usu, Japan, Abstracts of The Volcanol. Soc. Japan, 2000 No. 2, 22, 2000 (in Japanese).
Ossaka, J., Alteration of rocks in volcanic and hot spring area, Chinetsu, 17, 65–79, 1968 (in Japanese with English abstract).
Ossaka, J., Activity of volcanoes and clay minerals, J. Clay Sci. Soc. Japan, 22, 127–137, 1982 (in Japanese with English abstract).
Ossaka, J. and J. Hirabayashi, Clay minerals in volcanic ejecta, J. Mineral. Soc. Japan, 15, 223–238, 1981 (in Japanese with English abstract).
Ossaka, J. and T. Ozawa, The 1962-ejecta from Mt. Yake, Nagano-Gifu Prefectures and its Mechanism of Eruption, Bull. Volcanol. Soc. Japan, 11, 17–29, 1966 (in Japanese with English abstract).
Ui, T. and Geological party, Joint Obs. Team, 2000 eruption of Usu volcano: Chronology and disasters, Abstracts of The Volcanol. Soc. Japan, 2000 No. 2, 23, 2000 (in Japanese).
Ylagan, R. F., S. P. Altaner, and A. Pozzuoli, Hydrothermal alteration of a rhyolitic hyaloclastite from Ponza Island, Italy, J. Volcanol. Geotherm. Res., 74, 215–231, 1996.
Yokoyama, I., Y. Katsui, Y. Oba, and Y. Ehara, Usu-zan, its volcanic geology, history of eruption, present state of activity and prevention of disaster, Committee for Prevention of Disasters of Hokkaido, 254, 1973 (in Japanese).
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Nogami, K., Hirabayashi, J., Nishimura, Y. et al. Nature and origin of volcanic ash in the 2000 eruption of Usu volcano, southwestern Hokkaido, Japan. Earth Planet Sp 54, 993–998 (2002) doi:10.1186/BF03352447
- Clay Mineral
- Grain Size Analysis
- Summit Crater
- Historic Eruption