JpGU-AGU Joint Meeting 2017

Presentation information

[JJ] Poster

S (Solid Earth Sciences) » S-VC Volcanology

[S-VC48] [JJ] Hydrothermal systems of volcanoes

Thu. May 25, 2017 3:30 PM - 4:45 PM Poster Hall (International Exhibition Hall HALL7)

[SVC48-P08] Flux measurements of carbon dioxide at Beppu geothermal area using a portable non-dispersive infrared (NDIR) gas analyzer

*Koki Ogawa1, Tomo Shibata1, Taketoshi Mishima1, Keiji Takemura1, Shinji Ohsawa1 (1.Kyoto University)

Keywords:Beppu, hot spring, carbon dioxide

Degassing mechanisms play an important role for the Earth environment, since the current atmosphere and ocean have formed by release of volatile components from the solid Earth. The mechanisms may be catastrophic or continuous events; the former is a sudden release in a single event and the other is a process occurring throughout geological history of the Earth. A representative continuous degassing is volcanic activities. In the volcanic area, volatile components are released not only from the fumaroles but from the mountain body. Carbon dioxide (CO2) is one of the volatile components, and its release is affected by the volcanic activity (Hernandez et al., 2001). Degassing mechanisms of soil gases are dependent on underground structures such as geological strata, faults and fissures. Active faults can be good passageways (Dogan et al., 2009). Here, we have measured CO2 flux in the Beppu geothermal area, and reveal the degassing mechanisms of CO2 related to volcanic activities.

Beppu geothermal area located on central Kyushu direction, Japan is situated in graben zone formed by tensional stress, and is generated by western active volcanoes of Mt. Tsurumi and Garan. These volcanoes supply geothermal fluids on the area. Allis and Yusa (1989) measured the temperature under 100 m depth in the area, and revealed two parts with high temperature. The high temperature areas are located along the faults of northern and southen parts. Mine (2006) measured CO2 flux in the northern part and showed high values along the Kannawa fault. Here, we tried to measure CO2 flux in the southern part around the Horita and Asamigawa faults.

We used a chamber method which is measurement of concentration rate of CO2 in the vessel covered on the ground, and estimated CO2 flux at about 200 sites. The obtained CO2 fluxes range in 0.07-66.1 g/m2-day. High values of 2.71-66.1g/m2-day are observed on hot spring flows underground reported by Yusa and Ohsawa (2000), suggesting that CO2 gases are released from hot spring flows underground and raise to ground surface.


Allis R.G. and Yusa Y. (1989) Fluid flow processes in the Beppu geothermal system, Japan. Geothermics, 18, 743-759.

Dogan T. et al., (2009) Adjacent releases of mantle helium and soil CO2 from active faults: Observations from the Marmara region of the North Anatolian Fault zone, Turkey. G3, 10, Q11009.

Hernandez P. A. et al., (2001) Carbon Dioxide Degassing by Advective Flow from Usu Volcano, Japan. Science, 292, 83-86.

Mine T. (2006) A study on the appreciation of geothermal activities, using soil-CO2 flux profiles: A case study on Beppu Geothermal Area, Central Kyushu, Japan. 2006 Division of Earth and Planetary Sciences, Kyoto University Graduate School of Science, Geophysics Master thesis collection Ⅱ, 1-88.

Yusa Y. and Ohsawa S. (2000) Age of Beppu Onsen. Oita Prefecture Hot Spring Investigation Study Report,51, 1-8.