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[B-2.2 Studies for Estimation of Methane Flux from Volcanoes]

[Contact Person]

Masahiro Aoki
Senior Research Scientist
Mineral Resources Department, Geological Survey of Japan
Agency of Industrial Science and Technology
Ministry of International Trade and Industry
1-1-3 Higashi, Tsukuba, Ibaraki 305 Japan
Phone +81-298-54-3636, Fax +81-298-54-3533

[Total Budget for FY1993-1994]

8,907,000 Yen (FY1994 4,367,000 Yen)

[Abstract]

　Volcanoes are one of most important source of gas components in nature. Although methane is minor component of volcanic gas with concentration of an order of ppm, the methane flux from volcanoes could be important for geochemical cycle of methane during geological time scale. Emission rate of volcanic methane was evaluated through measured flux of CO₂ and CH₄/CO₂ value representative to each source. On the basis of the chemical analyses of gases from high temperature and low temperature fumatoles, geothermal well, submarine hydrothermal vents and soil around volcanoes(as soil gas), the maximum CH₄/CO₂ value for each source were estimated to be 10²-10³. These ratios multiplied by the CO₂ flux gave us the global methane to be less than 0.04 Tmol/year.

[Key Words]

Methane, Carbon Dioxide, Volcanic Gas, Soil Gas