Water discharge and recharge balance of Kuju volcano, Japan, deduced from thermal and gravity measurements

Yasuhiro Fujimitsu, Sachio Ehara, Yuuichi Nakano, Jun Nishijima, Masahiro Koya

Research output: Contribution to journalConference article

Abstract

Repeat thermal and gravity measurements have been conducted at Kuju volcano, an erupting volcano in central Kyushu, Japan, in order to monitor the underground geothermal fluid flow system. A very high level of heat discharge rate, over 2000 MW, had been maintained after the first phreatic eruption which created some new craters in October, 1995. However after the second eruption in December, 1995, the heat discharge rate from the new craters decreased rapidly. Nevertheless, the heat discharge rate from all fumarolic areas, in which the new craters are included, has maintained its value of 600 to 800 MW since September, 1996 to date. Gravity decreased rapidly just after the first eruption, and then decreased gradually. After some assumptions, underground water mass balance can be estimated by using the mass decrease data based on the Gauss's theorem and the steam discharge data. Estimation of mass balance of underground water shows that the recharge of ground water from the region around the new craters and the fumarolic areas was increasing after the eruption, and then, the underground water flow is gradually approaching a new equilibrium state.

Original languageEnglish
Pages (from-to)415-418
Number of pages4
JournalTransactions - Geothermal Resources Council
Volume23
Publication statusPublished - Dec 1 1999
EventGlobal Geothermal Resources: Sustainable Energy for the Future - Reno, NV, USA
Duration: Oct 17 1999Oct 20 1999

Fingerprint

Volcanoes
crater
Groundwater
recharge
Gravitation
volcano
volcanic eruption
gravity
Water
mass balance
water
water mass
fluid flow
Flow of fluids
water flow
Steam
groundwater
Hot Temperature
rate

All Science Journal Classification (ASJC) codes

  • Renewable Energy, Sustainability and the Environment
  • Energy Engineering and Power Technology
  • Geophysics

Cite this

Water discharge and recharge balance of Kuju volcano, Japan, deduced from thermal and gravity measurements. / Fujimitsu, Yasuhiro; Ehara, Sachio; Nakano, Yuuichi; Nishijima, Jun; Koya, Masahiro.

In: Transactions - Geothermal Resources Council, Vol. 23, 01.12.1999, p. 415-418.

Research output: Contribution to journalConference article

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AU - Ehara, Sachio

AU - Nakano, Yuuichi

AU - Nishijima, Jun

AU - Koya, Masahiro

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N2 - Repeat thermal and gravity measurements have been conducted at Kuju volcano, an erupting volcano in central Kyushu, Japan, in order to monitor the underground geothermal fluid flow system. A very high level of heat discharge rate, over 2000 MW, had been maintained after the first phreatic eruption which created some new craters in October, 1995. However after the second eruption in December, 1995, the heat discharge rate from the new craters decreased rapidly. Nevertheless, the heat discharge rate from all fumarolic areas, in which the new craters are included, has maintained its value of 600 to 800 MW since September, 1996 to date. Gravity decreased rapidly just after the first eruption, and then decreased gradually. After some assumptions, underground water mass balance can be estimated by using the mass decrease data based on the Gauss's theorem and the steam discharge data. Estimation of mass balance of underground water shows that the recharge of ground water from the region around the new craters and the fumarolic areas was increasing after the eruption, and then, the underground water flow is gradually approaching a new equilibrium state.

AB - Repeat thermal and gravity measurements have been conducted at Kuju volcano, an erupting volcano in central Kyushu, Japan, in order to monitor the underground geothermal fluid flow system. A very high level of heat discharge rate, over 2000 MW, had been maintained after the first phreatic eruption which created some new craters in October, 1995. However after the second eruption in December, 1995, the heat discharge rate from the new craters decreased rapidly. Nevertheless, the heat discharge rate from all fumarolic areas, in which the new craters are included, has maintained its value of 600 to 800 MW since September, 1996 to date. Gravity decreased rapidly just after the first eruption, and then decreased gradually. After some assumptions, underground water mass balance can be estimated by using the mass decrease data based on the Gauss's theorem and the steam discharge data. Estimation of mass balance of underground water shows that the recharge of ground water from the region around the new craters and the fumarolic areas was increasing after the eruption, and then, the underground water flow is gradually approaching a new equilibrium state.

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