Paper:
Time Variation in the Chemical and Isotopic Composition of Volcanic Gas at Mt. Mihara of Izu-Oshima Island, Japan
Takeshi Ohba*,†, Muga Yaguchi**, Kana Nishino*, and Nozomi Numanami*
*Department of Chemistry, School of Science, Tokai University
4-1-1 Kitakaname, Hiratsuka, Kanagawa 259-1292, Japan
†Corresponding author
**Volcanology Research Department, Meteorological Research Institute (MRI), Japan Meteorological Agency (JMA), Ibaraki, Japan
Volcanic gas was sampled at three fumaroles and one borehole on Mt. Mihara, Izu-Oshima volcano. The fumarolic gas and the borehole steam possessed an excess enthalpy relative to the air saturated with water vapor. The fumarolic gas located west of the pit crater on Mt. Mihara showed a time variation in chemical and isotopic composition. The cause of the variation seems to be an enhancement of water vapor condensation. No similar variation was observed in the fumarolic gas located east of the pit crater, suggesting the above variation is a phenomena localized around the western fumarole. Hydrogen gas was detected in the sampled gases with low concentration. The change in the H2 concentration synchronized among the three fumaroles, suggesting the H2 gas originated in the hydrothermal system developed beneath Mt. Mihara.
- [1] T. Fujii, S. Aramaki, T. Kaneko, K. Ozawa, Y. Kawanabe, and T. Fukuoka, “Petrology of the Lavas and Ejecta of the November, 1986 Eruption of Izu-Oshima Volcano,” Bull. Volcanol. Soc. Japan, Vol.33, Special Issue, pp. S234-S254, 1988 (in Japanese with English abstract).
- [2] Y. Kawanabe, “Geological Map of Izu-Ōshima Volcano,” Geological Map of Volcanoes No.10, Geological Survey of Japan, 1998.
- [3] T. Kagiyama and Y. Morita, “First Steps in Understanding Caldera Forming Eruptions,” J. Disaster Res., Vol.3, No.4, pp. 270-275, 2008.
- [4] A. Suwa and Y. Tanaka, “The Changes in the Temperatures of the Fumaroles in the Crater of Miharayama, Oshima, in Connection with the Activities of the Volcano,” Bull. Volcanol. Soc. Japan, Vol.3, No.2, pp. 107-118, 1959 (in Japanese with English abstract).
- [5] K. Notsu, T. Mori, S. C. Do Vale, H. Kagi, and T. Ito, “Monitoring Quiescent Volcanoes by Diffuse CO2 Degassing: Case Study of Mt. Fuji, Japan,” Pure Appl. Geophys., Vol.163, Issue 4, pp. 825-835, 2006.
- [6] Y. Shimoike and K. Notsu, “Continuous chemical monitoring of volcanic gas in Izu-Oshima volcano, Japan,” J. Volcanol. Geotherm. Res., Vol.101, Issues 3-4, pp. 211-221, 2000.
- [7] Y. Sano, T. Gamo, K. Notsu, and H. Wakita, “Secular variations of carbon and helium isotopes at Izu-Oshima volcano, Japan,” J. Volcanol. Geotherm. Res., Vol.64, Issues 1-2, pp. 83-94, 1995.
- [8] K. Kazahaya, M. Takahashi, and A. Ueda, “Discharge model of fumarolic gases during post-eruptive degassing of Izu-Oshima volcano, Japan,” Geochem. J., Vol.27, No.4-5, pp. 261-270, 1993.
- [9] T. Ohba, “Formation process of recent fumarolic gases at the Mt. Mihara summit peak of the Izu-Oshima volcano, Japan,” Earth Planet. Sp., Vol.59, Issue 10, pp. 1127-1133, 2007.
- [10] Japan Society of Mechanical Engineers (JSME), “1999 JSME Steam Tables,” 5th edition, Maruzen, 1999 (in Japanese).
- [11] H. Uchida, “Moist Air and Cooling Tower,” Revised edition, Shokabo, 1972 (in Japanese).
- [12] W. F. Giggenbach, “The origin and evolution of fluids in magmatic-hydrothermal systems,” H. L. Barnes (Ed.), “Geochemistry of Hydrothermal Ore Deposits,” 3rd edition, John Wiley & Sons, pp. 737-796, 1997.
This article is published under a Creative Commons Attribution-NoDerivatives 4.0 Internationa License.