V. Geochemical Study

Monitoring of Active Volcanoes Before, During and After the Eruption

Taking the opportunity for observation of erupting Unzen volcano, the volcanic SO2 flux was measured (Hirabayashi, 1995; Hirabayashi et al., 1995a). Before the eruption of Unzen volcano in 1990, several changes in the chemistry of fumarolic gas on the flank of volcano were detected (Ossaka et al., 1997a). Changes in the helium isotope ratio in hot spring around Unzen volcano was found after the start of eruption (LEC, 1995; LEC, 1997; Notsu, 1995). The phreatic eruption of Kuju volcano in 1995 produced many geochemical and related studies. Geothermal study by Ehara's group includes the estimation for the flux of volcanic gas and heat from Kuju volcano (LGT, 1996a; LGT, 1996b; LGT, 1997a; LGT, 1997b; LGT, 1998; Ehara and Fujimitsu, 1996; Ehara, 1997; Ehara, 1998). The chemical and isotopic composition of volcanic gas and hot spring waters from Kuju volcano were monitored (GSJ, 1996a; GSJ, 1996b; Hirabayashi et al., 1996a; KSVO, 1996b). The volcanic SO2 flux from Kuju volcano was periodically measured (SEVO, 1995; SEVO, 1996; SEVO, 1997a; SEVO, 1997c). The volcanic HCl flux was estimated by Itoi et al. (1997) and Ohsawa et al. (1997b). The chemistry of hot springs around Kuju volcano changed after the eruption (Kawano and Kawasaki, 1998; Miyazaki et al., 1998). The volcanic hydrothermal system under Kuju volcano was inferred based on tritium content in waters (Kitaoka et al., 1996a; Kitaoka et al., 1996b; Kitaoka et al., 1997). Because of the continuous activity, Sakurajima volcano has been monitored geophysically and geochemically. The volcanic gas diffused in the atmosphere on the flank of volcano was analyzed (Hirabayashi et al., 1995b; Hirabayashi et al., 1998a). SEVO (1997b) summarized the change in SO2 flux from Sakurajim volcano over years. Hirabayashi et al. (1998b) measured the SO2 fluxes from Sakurajima volcano employing the panning method and the traverse method simultaneously.Sakamoto (1995) and Sakamoto (1998) monitored the chemical composition of bubble gases exsolved from hot spring waters on the flank of Sakurajuma volcano. Satsuma-Iwojima is a volcanic island with a long lasting intense fumarolic activity at the summit. Changes in the fumarolic area and related observation were reported (GSJ, 1995; GSJ, 1997a; GSJ and SVO, 1997; GSJ and SVO, 1998). Kusatsu-Shirane volcano has a distribution of fumaroles and acidic hot springs on the flank, which have been the objects for geochemical monitoring (Hirabayashi and Ohba, 1996; Hirabayashi, 1997; KSVO, 1996a; Ossaka et al., 1998b). Kusatsu-Shirane volcano has acidic crater lakes on the summit. The change in the chemistry of lake water enabled geochemists to evaluate the volcanic activity (KSVO, 1997; Ossaka et al., 1997b). Continuous chemical monitoring of fumarolic gas is difficult in spite of the potential to evaluating volcanic activity. A system for continuous gas monitoring system was developed at Izu-Oshima volcano (LEC, 1998; Shimoike et al., 1997). Kagiyama and Koyama (1997) found a definite correlation between fumarolic temperature and atmospheric temperature at Kusatsu-Shirane volcano. Geochemical monitoring was also carried out at volcanoes other than above (LEC, 1996; Hirabayashi et al., 1996b; Iriyama, 1995; Iriyama et al., 1995; Symonds et al., 1996). A direct sampling of gas from erupting volcano is difficult and dangerous. Ossaka et al. (1998a) indicated that the water-soluble components adsorbed in volcanic ash could be an alternate for the composition of volcanic gas. A remote measurement for the chemical composition of volcanic gas was successful with the use of FT-IR spectrometry (Mori et al., 1995; Mori and Notsu, 1997; Mori, 1997). Notsu (1997) discussed the strategy of geochemical study for predicting volcanic eruption.

Studies on Gas and Water Related to Volcanic Activity

Kiyosu and Okamoto (1998) and Delmelle et al. (1998) inferred the hydrothermal structure of Nasudake and Taal volcanoes, respectively, based on the chemistry and isotope of fumarolic gas. Higashihara et al. (1997), Kiyosu and Asada (1995), Sugisaki and Nagamine (1995) measured content and composition of hydrocarbons contained in fumarolic gases. Hernandez et al. (1998) determined the flux of gases diffusely degassed from Teide volcano. Iwasaki (1995) and Kazahaya (1997) reviewed the studies on H2O discharged from volcanoes. Koga et al. (1995) developed a geothermometer applicable to gaseous phase. Ohba (1997) discussed chemical equilibrium among chemical species in volcanic gases. Inert composition in fumarolic gas from several volcanoes were analyzed by Ohsawa et al. (1995b), Ohsawa et al. (1997a), Ohsawa et al. (1998a) and Ohsawa et al. (1998b). Sano et al. (1996), Sano et al. (1997) and Sano et al. (1998a) measured helium and carbon isotopic ratios in fumarolic gases from Kusatsu-Shirane, Galeras and Ontake volcanoes, respectively. Taran et al. (1998) studied the volcanic-hydrothermal system of El Chichon volcano. Miyake and Ossaka (1998) reported the composition of gas from Nakanoyu hot spring at which a steam explosion occurred. Saito (1997) introduced the field workshop for volcanic gas research held at Kilauea volcano. Volcanoes in Japan associate many hot springs. A lot of studies on the chemistry and isotopes of hot springs were carried out (Koizumi et al., 1997; Nedachi et al., 1995; Oi et al., 1996; Tsuji et al., 1997). Goto (1997) summarized the chemistry of acidic hot springs in Japan. The chemistry of waters related a steam explosion occurred at Sumikawa spa was reported (GSJ, 1997b; Takahashi and Endo, 1997). Horiuchi et al. (1996), Kuriya et al. (1997) and Matsubaya (1997) summarized chemistry of hot spring in Gunma, Kanagawa and Akita prefectures, respectively. Kawabe (1997) analyzed the movement of geothermal water under Unzen volcano. Yamamoto et al. (1997) and Yamano et al. (1995) studied the hot spring waters from Kusatsu-Shirnane volcano. The studies by Sasaki (1997) and Yanagisawa (1997) are subjected to the chemistry of water from Tamagawa spa, famous as the strong acidity. Ohsawa et al. (1996), Oue et al. (1998) and Takamatsu et al. (1998) studied the chemistry of a hot water pool at Beppu spa. A mineral deposit in hot spring water was studied by Usui and Mita (1995). Oue et al. (1996) developed a geothermometer applicable to acidic water. Yusa (1996) discussed the origin of Cl- in hot spring water. Igarashi et al. (1997) developed a monitoring system for dissolved gases in spring water. The lake water on active volcanoes contains chemical components originates in degassing magma. The accumulation of CO2 gas still continues in Lake Nyos of Cameroon (Kusakabe et al., 1995; Kusakabe, 1996a; Kusakabe, 1996c). The sulfur species in lake water are interested because of the magmatic origin (Takano et al., 1995; Takano, 1996; Takano, 1997). Isotopic ratios of lake water and the chemical composition provide information on volcanic activities (Kusakabe, 1997; Kusakabe and Takano, 1998; Ohba et al., 1995; Maekawa, 1997). Fukui (1995) estimated the flux of evaporating H2O from the hot crater lake on Aso volcano. KSVO (1997) reported an abrupt discharge of steam from the crater lake of Kusatsu-Shirane volcano. The study on mineral deposit associated with ancient volcanoes contributes the understanding to the volcanic-hydrothermal system (Arribas et al., 1995; Yamamoto, 1995). Many studies on rare gases were carried out for the understanding magmatic and volcanic-hydrothermal processes (Hanyu, 1995 Hanyu, 1996; Hanyu and Kaneoka, 1997; Kaneoka et al., 1997; Kaneoka, 1998; Kita and Nagao, 1996; Lesniak et al., 1997; Mahara, 1995; Matsubara and Matsuda, 1995; Matsuda and Marty, 1995; Nakai et al., 1997; Sano et al., 1995; Sano, 1996). As the degassing of volatile from molten magma is the driving force for volcanic eruptions, the physics of degassing, the solubility of volatile in magma and the content of volatile in magma are important (Kazahaya, 1996; Kazahaya and Shinohara, 1996; Kusakabe, 1996b; Miyagi et al., 1997; Miyagi et al., 1998; Shinohara and Kazahaya, 1995; Shinohara et al., 1995; Shinohara and Hedenquist, 1997; Yamashita et al., 1997; Miyagi and Yurimoto, 1995). The chemical and isotopic compositions of volatile with low reactivity such as rare gas and N2 contained in volcanic gas and lava provides information on the transport of volatile from subducting plate (Kita, 1995; Kita et al., 1995; Kita, 1997; Nishio et al., 1998; Sano and William, 1996; Sano et al., 1998b). Hirabyashi (1998) reviewed natural disasters caused by gases from Japanese volcanoes. The understanding to volcanic-hydrothermal system was enriched by geothermal studies (Komatsu et al., 1998; Lima et al., 1996; Matsubaya, 1995; Matsubaya, 1996; Matsubaya, 1998; Ohsawa et al., 1995a; Sasada and Goff, 1995; Strchio et al., 1996; Takahashi, 1996; Tsunogai et al., 1996; Yokoyama et al., 1996; Seki, 1995; Seki, 1996; Shigeno et al., 1995; Ueda, 1996).

Studies on Volcanic Activity on Sea-floor, the Interaction Between Rock and Water and the Volatile Elements in Volcanic Materials.

Despite the difficulty of access, the number of researches for the volcanism on sea floor is increasing (Gamo et al., 1997; Iizasa, 1997; Ishibashi et al., 1995; Ishibashi et al., 1997; Ishibashi, 1997; Kajiwara, 1996; Kawahata et al., 1997; Ossaka et al., 1996; Sakamoto et al., 1995; Sasaki et al., 1995; Tsunogai, 1997; Usui and Terashima, 1997; Watanabe et al., 1995; Feely et al., 1996). Several studies were made on the interaction between acidic water and volcanic rock, which is a prevailing geological process at volcanic area (Kikawada et al., 1995; Minami et al., 1995; Nogami and Yoshida, 1995; Ossaka, 1995; Terakado and Fujitani, 1998). Volatile elements in volcanic rocks and minerals were studied by Anazawa and Yoshida (1996), Ebihara (1997), Terakado and Nakajima (1995) and Muramatsu and Wedepohl (1998).

Abbreviation for organizations of research

GSJ: Geological Survey of Japan

KSVO: Kusatsu-Shirane Volcano Obs. Tokyo Institute of Technology

LEC: Laboratory for Earthquake Chemistry, Univ. of Tokyo

LGT: Laboratory of Geothermics, Kyushu Univ.

SEVO: Shimabara Earthquake and Volcano Obs., Kyushu.Univ.

SVO: Sakurajima Volcano Research Center, Kyoto Univ.

(Takeshi Ohba)

Refererences

Anazawa, K. and Yoshida, M. (1996) Multivariate analysis of Japanese volcanic rocks: Volatile and major elements. Geochem. Jour., 30, 355-372.

Arribas, A. J., Hedenquist, J. W., Itaya, T., Okada, T. and Garcia, J. S. (1995) Contemporaneous formation of adjacent porphyry and epthermal Cu-Au deposits over 300ka in northern Luzon, Philippins. Geology, 23, 337-340.

Delmelle, P., Kusakabe, M., Bernard, A., Fischer, T., Brouwer, S. and Mundo, E. (1998) Geochemical and isotopic evidence for seawater contamination of the hydrothermal system of Taal Volcano, Luzon, the Philippines. Bull. Volcanol., 59, 562-576.

*Ebihara, M. (1997) Halogen abundances in crustal rocks. Bull. Volcanol. Soc. Japan, 42, S303-S312.

**Ehara, S. (1997) Thermal process under Kuju volcano and the eruption in 1995. Gekkan-Chikyu, 17, 106-111.

*Ehara, S. (1998) 1995 eruption of Kuju volcano and its recent activities. Jour. Balneol. Soc. Japan, 48, 72-83.

**Ehara, S. and Fujimitsu, Y. (1996) Thermal and 1995 eruption processes of Kuju volcano, central Kyushu, Japan. Rep. Grant-in-Aid for Sci. Res. (leaded by Kobayashi, H.) Research on Oct.1995 Phreatic Eruption at Kuju Volcano, pp. 15-31.

Feely, R. A., Baker, E. T., Gendron, J., Lebon, G. T., Marumo, K., Urabe, T. and Ishibashi, J. (1996) Hydrothermal plume particles and dissolved phosphate over the superfast-spreading southern East Pacific Rise. Geochim. Cosmochim. Acta, 60, 2297-2323.

*Fukui, K. (1995) H2O and heat discharged from Aso volcano in Noneruptive stage. Bull. Volcanol. Soc. Japan, 40, 233-248.

Gamo, T., Okamura, K., Ishibashi, J., Urabe, T., Shitashima, K. and Chiba, H. (1997) Acidic and sulfate-rich hydrothermal fluids from the Manus back-arc basin, Papua New Guinea. Geology, 25, 139-142.

**Goto, T. (1997) Chemistry of acidic hot springs in Japan: Tamagawa hot spring. Mizu, 39, 68-76.

**GSJ (1995) Outline of recent volcanic activity changes at the summit of Iwodake, Satsuma-Iwojima. Rep. Coord. Commit. Pred. Volc. Eruption, 63, 94-95.

**GSJ (1996a) Continuous monitoring of volcanic gases and temperature at Kuju volcano. Rep. Coord. Commit. Pred. Volc. Eruption, 65, 82-85.

**GSJ (1996b) Chemical and isotopic compositions of volcanic gases and hot springs of Kuju volcano (October 1995-October 1996). Rep. Coord. Commit. Pred. Volc. Eruption, 66, 95-99.

**GSJ (1997a) Recent volcanic activity at the summit of Iwodake, Satsuma-Iwojima. Rep. Coord. Commit. Pred. Volc. Eruption, 67, 79-82.

**GSJ (1997b) Geochemical survey for hot and mineral springs, related to the 1997 Sumikawa landslide with hydrothermal explosions, Akita prefecture. Rep. Coord. Commit. Pred. Volc. Eruption, 68, 13-14.

**GSJ and SVO (1997) Recent volcanic activity at the summit of Iwodake, Satuma-Iwojima until April 1997. Rep. Coord. Commit. Pred. Volc. Eruption, 68, 97-99.

**GSJ and SVO (1998) Recent volcanic activity at the summit of Iwodake, Satsuma-Iwojima unitl Nov. 1997. Rep. Coord. Commit. Pred. Volc. Eruption, 70, 59-61.

*Hanyu, T. (1995) Magma dynamics. Bull. Volcanol. Soc. Japan, 40, S79-S89.

**Hanyu, T. (1996) Interaction between magma and underground water -the case of Unzen volcano. Gekkan-Chikyu, 15, 161-165.

Hanyu, T. and Kaneoka, I. (1997a) Magmatic processes revealed by noble gas signatures: the case of Unzen volcano, Japan. Geochem. Jour., 31, 395-405.

Hanyu, T. and Kaneoka, I. (1997b) Uniform and low 3He/4He of Polynesian HIMU: evidnce for recycled materials. Nature, 390, 273-276.

Hanyu, T. and Kaneoka, I. (1998) Open system behavior of helium in case of the HIMU source area. Geophys. Res. Lett., 25, 687-690.

Hernandez, P. A., Perez, N. M., Nakai, S., Notsu, K., Wakita, H. and Salazar, J. M. (1998) Diffuse emission of carbon dioxide, methane, and helium-3 from Teide volcano, Tenerife, Canary islands. Geophys. Res. Lett., 25, 3311-3314.

Higashihara, M., Igari, S., Maekawa, T., Noda, T., Sakata, S., Asada, N. and Miyatake, A. (1997) C5+ hydrocarbons in fumarolic gases from Kakkonda (Takinoue) geothermal area, Japan. Geochem. Jour., 31, 63-73.

**Hirabayashi, J. (1995) Volcanic gas flux from Unzen volcano. Gekkan-Chikyu, 15, 151-155.

**Hirabayashi, J. (1997) Recent volcanic activity of Kusatsu-Shirane volcano and geochemical observation and research. Gekkan-Chikyu, 18, 70-75.

*Hirabayashi, J. (1998) Volcanic gas disaster in Japan. Jour. Japan. Disast. Medicine, 3, 11-17.

**Hirabayashi, J. and Ohba, T. (1996) Geochemical observation of Kusatsu-Shirane volcano. Rep.3th Join Obs. Kusatsu-Shirane Volc., pp. 3-11.

**Hirabayashi, J., Ohba, T. and Nogami, K. (1996a) Geochemical study associated with the 1995 eruption of Kuju volcano, Kyushu, Japan. Rep. Grant-in-Aid for Sci. Res. (leaded by Kobayashi, H.) Research on Oct.1995 Phreatic Eruption at Kuju Volcano, pp. 63-73.

*Hirabayashi, J., Ohba, T. and Nogami, K. (1996b) Chemical composition of volcanic gases associated with the 1991-1992 activity of Shinmoe-dake, Kirishima volcanoes, Japan. Bull. Volcanol. Soc. Japan, 41, 263-267.

Hirabayashi, J., Ohba, T., Nogami, K. and Yoshida, M. (1995a) Discharge rate of SO2 from Unzen volcano, Kyushu, Japan. Geophys. Res. Lett., 22, 1709-1712.

**Hirabayashi, J., Ohba, T., Eto, T., Iguchi, M. and Sakamoto, H. (1995b) Chemical composition of volcanic gas from Sakurajima volcano: Corrlation to the volcanic activity (8). Rep.8th Join Obs. Sakurajima Volc., pp. 55-70.

**Hirabayashi, J., Ohba, T., Nogami, K., Eto, T., Iguchi, M. and Sakamoto, H. (1998a) Chemical composition of volcanic gas from Sakurajima volcano: Corrlation to the volcanic activity (9). Rep. 9th Join Obs. Sakurajima Volc., pp. 91-100.

**Hirabayashi, J., Ohba, T., Nogami, K., Ohta, K., Shimizu, H., Matsuo, N., Kazahaya, K. and Shinohara, H. (1998b) SO2 flux from Sakurajima volcano. Rep. 9th Join Obs. Sakurajima Volc., pp. 113-118.

*Horiuchi, K., Sakai, Y., Seki, S. and Kogure, K. (1996) On the thermal springs and radon concentration in Gunma prefecture. Jour. Balneol. Soc. Japan, 46, 79-86.

*Igarashi, J., Shimoike, Y., Sato, M., Notsu, K., Takahata, N. and Sano, Y. (1997) A new system for continuous measurements of elemental and isotopic ratios of gases dissolved in groundwater using a quadrupole mass spectrometer and a gas-permeable membrane. Chikyukagaku, 31, 81-88.

**Iizasa, K. (1997) Too late: The discovery of sulfide chimneys in the Myojin knoll caldera. Chishitsu News, 514, 30-37.

Iriyama, J. (1995) Geothermal activity and process of the Yakedake volcano, Gifu-Nagano, Japan. Geotherm. Resour. Counc. Bull., 24, 305-310.

Iriyama, J., Kobayashi, Y., Hotaka, A. and Higashigawa, T. (1995) Nature of the Yakedake volcano, Gifu-Nagano, Japan: Hot water and geothermal activity. Mem. Coll. Eng. Chubu. Univ., 31, 133-137.

**Ishibashi, J. (1997) Investigation of hydrothermal system at sea floor based on helium. Gekkan-Chikyu, 18, 88-92.

Ishibashi, J., Sano, Y., Wakita, H., Gamo, T., Tsutsumi, M. and Sakai, H. (1995) Helium and carbon geochemistry of hydrothermal fluids from the Mid-Okinawa trough back arc basin, southwest of Japan. Chem. Geol., 123, 1-15.

Ishibashi, J., Wakita, H., Okamura, K., Feely, R. A., Lebon, G. T. and Marumo, K. (1997) Hydrothermal methane and manganese variation in the plume over the superfast-spreading southern East Pacific Rise. Geochim. Cosmochim. Acta, 61, 485-500.

Itoi, R., Kai, T. and Fukuda, M. (1997) Volcanic activity of Kuju volcano and its effects on acidification of rain in the local area. Proc. Int. Cong. Acid Snow Rain 1997, pp. 148-153.

*Iwasaki, I. (1995) Juvenile water and magmatic water. Jour. Balneol. Soc. Japan, 45, 1-12.

*Kagiyama, T. and Koyama, E. (1997) On a relation between fumarolic temperature and atmospheric pressure. Bull. Volcanol. Soc. Japan, 42, 423-428.

**Kajiwara, Y. (1996) Hydrothermal vent ores in the mid-oceanic ridges: Transitory products of the deep-sea hydrothermal ecosystems. Chishitsu News, 497, 34-45.

Kaneko, T., Kaneoka, I. and Kawachi, S. (1996) Geochemistry of Quaternary basalts from the Yatsugadake volcano, central Japan: generation of an unusually deep Wadachi-Benioff zone beneath the volcanic front by double-overlapping subduction. Geochem. Jour., 30, 155-173.

Kaneoka, I. (1998a) Noble gas signatures in the Earth's interior-coupled or decoupled behavior among each isotope systematics and problems related to their implication. Chem. Geol., 147, 61-76.

Kaneoka, I. (1998b) Xenon's inside story. Science, 280, 851-852.

Kaenoka, I. (1998c) Noble gas signatures in the Earth's interior -coupled or decoupled behavior among each isotope systematics and problems related to their implication. Chem. Geol., 147, 61-76.

*Kaneoka, I., Hanyu, T. and Kumagai, H. (1997) Noble gas isotopes and characteristics of magma sources -present status and problems-. Bull. Volcanol. Soc. Japan, 42, S313-S319

*Kawabe, H. (1997) Flow of geothermal water around Mayu-yama, Unzen volcano. Bull. Volcanol. Soc. Japan, 42, 359-366.

Kawahata, H., Kusakabe, M. and Scott, S. D. (1997) Sulfate in plagiogranites from the Troodos ophiolite, Cyprus. Geochem. Jour., 31, 119-124.

**Kawano, T. and Kawasaki, Y. (1998) Chemical composition of spontaneous gush springs, ground water and the like in Kuju volcanic zone. Rep. Oita Hot spring Res. Assoc., 49, 1-3.

*Kazahaya, K. (1996) Volatiles and magmatic processes - contribution to prediction of volcanic eruptions -. Bull. Volcanol. Soc. Japan, 42, 119-123.

*Kazahaya, K. (1997) Discharged H2O from acitve island arc volcanoes: Origin and flux. Jour. Japan. Assoc. Hydrol. Sci., 27, 105-116.

*Kazahaya, K. and Shinohara, H. (1996) Excess degassing of active volcanoes: processes and mechanisms. Mem. Geol. Soc. Japan, 46, 91-104.

Kikawada, Y., Oi, T., Ossaka, T., Kakihana, H. and Honda, T. (1995) Leaching of lanthanoids from andesitic rocks by acidic aqueous solutions. Geochem. Jour., 29, 67-84.

**Kita, I. (1995) Implication of magmatic N2/Ar and 3He/4He ratios in strange state of plate subduction beneath the Beppu-Shimabara graben, Kyusyu, Japan. Chishitsu News, 488, 19-23.

**Kita, I. (1997) Magmatic gas and petrochemical features of volcanic rocks from Beppu-Shimabara graben: implication to the magmatism. Gekkan-Chikyu, 18, 42-47.

**Kita, I. and Nagao, K. (1996) Evaluation of collection methods and He isotopic ratios of gas samples from deep oil exploration wells. Chishitsu News, 506, 29-34.

*Kita, I., Hasagawa, H., Takizawa, H., Nitta, K. and Taguchi, S. (1995) Carbon isotopic difference of magmatic CO2 between northeast and southwest Japan. Rep. Res. Inst. Underground Res., Mining Coll. Akita Univ., 60, 35-38.

**Kitaoka, K., Ohsawa, S. and Oue, K. (1996b) Tritium content in the fumarolic gas and hot spring waters from Kuju-Iwoyama volcano. Rep. Oita Hot spring Res. Assoc., 47, 21-28.

*Kitaoka, K., Ohsawa, S., Yusa, Y. and Kusakabe, M. (1996a) Changes in the chemical and isotopic compositions of deep geothermal waters through subsurface boiling at Kuju-Iwoyama volcano, central Kyushu, Japan. Jour. Balneol. Soc. Japan, 46, 156-175.

**Kitaoka, K., Ohsawa, S., Oue, K. and Yusa, Y. (1997) A deep circulation of hydrothermal water inferred from Tritium content. Rep. Oita Hot spring Res. Assoc., 48, 21-29.

Kiyosu, Y. and Asada, N. (1995) Light hydrocarbons in volcanic gases from the Japanese island arc. Geochem. Jour., 29, 231-242.

Kiyosu, Y. and Okamoto, Y. (1998) Variation in fumarolic H2 gas andvolcanic activity at Nasudake in Japan. Jour. Volcanol. Geotherm. Res., 80, 27-37.

*Koga, A., Kita, I., Hikino, E., Nitta, K. and Taguchi, S. (1995) New gas geothermometers using CO2/H2 and CH4/H2 ratios. Jour. Geotherm. Res. Soc. Japan, 17, 201-211.

**Koizumi, N., Kazahaya, K., Takahashi, M. and Kitagawa, Y. (1997) Changes in the content of magmatic gases due to the change of permeability -the case of Koshimizu observation well, Izu-Oshima. Gekkan-Chikyu, 18, 36-40.

*Komatsu, R., Ikeuchi, K., Doi, N., Sasaki, M., Uchida, T. and Sasada, M. (1998) Charactesistics of the Quaternary Kakkonda granite and geothermal system clarified by fluid inclusions study of deep investigation well, Kakkonda, Japan. Jour. Geotherm. Res. Soc. Japan, 20, 209-224.

**KSVO (1996a) The activity on February, 1996 of Kusatsu-Shirane volcano. Rep. Coord. Commit. Pred. Volc. Eruption, 65, 29-32.

**KSVO (1996b) Geochemical study on volcanic activity of Kuju volcano, after the 1995 eruption. Rep. Coord. Commit. Pred. Volc. Eruption, 65, 73-79.

**KSVO (1997) The occurrence of sudden gas jet and water dome at Yugama crater on 2nd May, 1997. Rep. Coord. Commit. Pred. Volc. Eruption, 68, 33-34.

Kumagai, H. and Kaneoka, I. (1998) Variations of noble gas abundances and isotope ratios in a single MORB pillow. Geophys. Res. Lett., 25, 3891-3894.

Kumagai, H., Kaneoka, I. and Ishii, T. (1996) The active period of the Ayu trough as estimated from K-Ar ages: the southeastern spreading center of Philippine Plate. Geochem. Jour., 30, 2, 81-87.

**Kuriya, T., Ishizaka, N. and HIrano, T. (1997) Characteristics of the hot springs in Kanagawa. Bull. Hot Spring Res. Inst. Kanagawa Pref., 28, 53-76.

**Kusakabe, M. (1996a) Accumulation of magmatic CO2 in the lake water of Nyos. Gekkan-Chikyu, 16, 126-130.

*Kusakabe, M. (1996b) D/H variations during magma degassing -a case study for the Unzen 1991 and Mt. Fuji 1707 eruptions-. Mem. Geol. Soc. Japan, 46, 105-113.

*Kusakabe, M. (1996c) International cooperation towards mitigation of lake Nyos-type gas disasters. Bull. Volcanol. Soc. Japan, 42, 99-103.

**Kusakabe, M. (1997) Sulfur and oxygen isotopic ratios of sulfate ion in lake water at active volcanic craters: implication to magma-hydrothermalsystem. Gekkan-Chikyu, 18, 82-86.

Kusakabe, M. and Takano, B. (1998) Sulfur and oxygen isotopic variations of dissolved sulfate in crater lake, Mt Ruapehu, New Zealand. Proc.9th Int. Symp. Water-Rock Interaction, pp. 463-466.

Kusakabe, M., Tanyileke, G. Z., Nojiri, Y. and Kita, I. (1995) Decreasing thermal and chemical fluxes at Lake Nyos, Cameroon. Proc.8th Int. Symp. Water-Rock interaction, pp. 311-313.

**LEC (1995) Temporal variations in 3He/4He ratios of hot spring gases around Unzen-dake Volcano. Rep. Coord. Commit. Pred. Volc. Eruption, 63, 86-87.

**LEC (1996) Carbon isotopic composition of methane in volcanic gas from Hokkaido-Komagatake volcano. Rep. Coord. Commit. Pred. Volc. Eruption, 65, 8.

**LEC (1997) Temporal variations in 3He/4He ratios of hot spring gases around Unzen-dake volcano (November 1995-December 1996). Rep. Coord. Commit. Pred. Volc. Eruption, 67, 72-73.

**LEC (1998) Continuous measurement of chemical composition of fumarolic gas at Izu-Oshima volcano. Rep. Coord. Commit. Pred. Volc. Eruption, 70, 28-31.

Lesniak, P. M., Sakai, H., Ishibashi, J. and Wakita, H. (1997) Mantle helium signal in the west Carpathians, Poland. Geochem. Jour., 31, 383-394.

**LGT (1996a) Thermal and mass flow measurements after 1995 eruption of Kuju volcano. Rep. Coord. Commit. Pred. Volc. Eruption, 65, 66-70.

**LGT (1996b) Thermal and mass flow measurements after the 1995 eruption of Kuju volcano (part 2). Rep. Coord. Commit. Pred. Volc. Eruption, 66, 88-92.

**LGT (1997a) Thermal and mass flow measurements after the 1995 eruption of Kuju volcano (part 3). Rep. Coord. Commit. Pred. Volc. Eruption, 67, 52-54.

**LGT (1997b) Thermal and mass flow measurements after the 1995 eruption of Kuju volcano (part 4). Rep. Coord. Commit. Pred. Volc. Eruption, 68, 69-72.

**LGT (1998) Thermal and mass flow measurements after the 1995 eruption of Kuju volcano (part 5). Rep. Coord. Commit. Pred. Volc. Eruption, 69, 91-95.

Lima, E., Fujino, T., Mcnitt, J. R., Klein, C. W., Greensfelder, R. W., Robertsontait, A., Roldan, A. and Palmaj (1996) A hydrogeological and geochemical model of the high-temperature geothermal system of Amatitlan, Guatemala. Trans. Geotherm. Resour. Counc., 20, 347-352.

**Maekawa, T. (1997) Layered structure of water in volcanic crater lake and helium isotope in the lake water. Gekkan-Chikyu, 18, 103-108.

Mahara, Y. (1995) Noble gases dissolved in groundwater in a volcanic aquifer: Helium isotopes in the Kumamoto Plain. Environ. Geol., 25, 215-224.

Matsubara, K. and Matsuda, J. (1995) Laboratory experiments on the Ne enrichments in terrestrial natural glasses. Geochem. Jour., 29, 293-300.

Matsubaya, O. (1995) Two geothermal systems of volcanic and meteoric origins within the same area in Hachimantai, Akita, Japan. Proc.8th Int. Symp. Water-Rock Interaction, pp. 519-522.

**Matsubaya, O. (1996) Geothermal systems in Japan based on hydrogen and oxygen isotope of thermal water. Gekkan-Chikyu, 16, 154-158.

*Matsubaya, O. (1997) Isotopic and chemical features of hot springs in Akita prefecture. Jour. Balneol. Soc. Japan, 47, 104-110.

*Matsubaya, O. (1998) Necessity of understanding the structure of geothermal reservoir. Jour. New Energy Foundation, 23, 125-131.

Matsuda, J. and Marty, B. (1995) The 40Ar/36Ar ratio of the undepleted mantle: a reevaluation. Geophys. Res. Lett., 22, 1937-1940.

Minami, M., Masuda, A. and Matsuda, N. (1995) Experimental studies on behaviors of lanthanides in interaction between water and basaltic rock grains. Bearings of tetrad effect on conditions. Proceed. Japan. Acad. Ser B, 71, 10-14.

Miyagi, I., Matsubaya, O. and Nakashima, S. (1998) Change in D/H ratio, water content and color during dehydration of hornblende. Geochem. Jour., 32, 33-48.

Miyagi, I. and Yurimoto, H. (1995) Water content of melt inclusions in Phenocrysts using secondary ion mass spectrometer. Bull. Volcanol. Soc. Japan, 40, 349-355.

Miyagi, I., Yurimoto, H. and Takahashi, E. (1997) Water solubility in albite-orthoclase join and JR-1 rhyolite melts at 1000 C and 500 to 2000 bars, determined by micro-analysis with SIMS. Geochem. Jour., 31, 57-61.

*Miyake, Y. and Ossaka, J. (1998) Steam explosion of February 11th, 1995 at Nakanoyu hot spring, Nagano prefecture, central Japan. Bull. Volcanol. Soc. Japan, 43, 113-121.

**Miyazaki, T., Touda, T. and Shutou, T. (1998) Survey on the actual conditions of hot springs around Mt. Io-zan caused by its phreatic explosion. Rep. Oita Hot spring Res. Assoc., 49, 43-47.

**Mori, T. (1997) Remote observation of chemical composition in volcanic gas using infrared spectrometry. Gekkan-Chikyu, 18, 59-63.

Mori, T. and Notsu, K. (1997) Remote CO, COS, CO2, SO2, HCl detection and temperature estimation of volcanic gas. Geophys. Res. Lett., 24, 2047-2050.

Mori, T., Notsu, K., Tohjima, Y., Wakita, H., Nuccio, P. M. and Italiano, F. (1995) Remote detection of fumarolic gas chemistry at Vulcano, Italy, using an FT-IR spectral radiometer. Earth Planet. Sci. Lett., 134, 219-224.

Muramatsu, Y. and Wedepohl, K. H. (1998) The distribution of iodine in the earth's crust. Chem. Geol., 147, 201-216.

Nakai, S., Wakita, H., Nuccio, M. and Italiano, F. (1997) MORB-type neon in an enriched mantle beneath Etna, Sicily. Earth Planet. Sci. Lett., 153, 57-66.

Nedachi, M., Nedachi, Y. and Taguchi, S. (1995) Preliminary study on the hotspring waters in the Ladolam gold deposit area, Lihir island, Papua New Guinea. South Pacific Study, 16, 117-126.

Nishio, Y., Sasaki, S., Gamo, T., Hiyagon, H. and Sano, Y. (1998) Carbon and helium isotope systematics of north Fiji basin basalt glasses: carbon geochemical cycle in the subducttion zone. Earth Planet. Sci. Lett., 154, 127-138.

Nogami, K. and Yoshida, M. (1995) Leaching rates of rock-forming components through acidic alteration. Jour. Volcanol. Geotherm. Res., 65, 41-49.

**Notsu, K. (1995) Changes in underground fluid after the eruption of Unzen volcano caused by the magma ascending. Gekkan-Chikyu, 15, 156-160.

**Notsu, K. (1997) Geochemical observation and research for the prediction of earthquakes and volcanic eruptions. Gekkan-Chikyu, 18, 53-58.

*Ohba, T. (1997) Chemical equilibrium in high temperature volcanic gas. Chikyukagaku, 31, 99-110.

Ohba, T., Nogami, K. and Hirabayashi, J. (1995) Isotope ratios of lake water in the active crater at Kusatsu-Shirane volcano, Japan. Proc. 8th Int. Symp. Water-Rock Interaction, pp. 321-322.

*Ohsawa, S., Yusa, Y. and Wang, Y. (1995a) Geochemical modelling of hydrothermal system in Tengchong volcanic region, Yunnan province, China. Jour. Balneol. Soc. Japan, 45, 13-25.

*Ohsawa, S., Yusa, Y. and Kitaoka, K. (1995b) Inert gas compositions of fumarolic gases discharged from Kirishima volcano, southwestern Japan. Jour. Balneol. Soc. Japan, 45, 290-294.

*Ohsawa, S., Oue, K. and Yusa, Y. (1996) Discoloration of hot-spring deposits of the hot pool "Chinoike-Jigoku", in Beppu geothermal area, central Kyushu, Japan. Jour. Balneol. Soc. Japan, 46, 13-19.

*Ohsawa, S., Yusa, Y., Oue, K. and Kitaoka, K. (1997a) Inert gas compositions of fumarolic gases discharged from the Aso volcanic-geothermal region, Japan. Jour. Balneol. Soc. Japan, 47, 56-67.

*Ohsawa,S., Yusa,Y., Kitaoka,K (1997b) Estimation of HCl and magmatic steam fluxes from the fumarole area at Kuju-Iwoyama volcano, central Kyushu, Japan. Jour. Geotherm. Res. Soc. Japan, 19, 73-83.

*Ohsawa, S., Yusa, Y. and Oue, K. (1998b) Chemical compositions of gases discharged from fumaroles and steam wells in the Takenoyu geothermal area, Kyushu, Japan. Jour. Geotherm. Res. Soc. Japan, 20, 289-292.

*Ohsawa, S., Yusa, Y., Oue, K. and Kitaoka, K. (1998a) Low N2/He ratio magmatic gas discharged from Ogasawara-Iwojima in Izu-Mariana arc along an oceanic subduction zone between Pacific and Philippine-sea plates. Jour. Balneol. Soc. Japan, 48, 9-14.

Oi, T., Ikeda, K., Nakano, M., Ossaka, T. and Ossaka, J. (1996) Boron isotope geochemistry of hot spring waters in Ibusuki and adjacent areas, Kagoshima, Japan. Geochem. Jour., 30, 273-287.

*Ossaka, J. (1995) Rock alteration and chemical components in hot spring water. Jour. Balneol. Soc. Japan, 45, 159-167.

*Ossaka, J., Nogami, K. and Hirabayashi, J. (1998a) Water-soluble components on volcanic ashes from Tokachi-dake volcano, Hokkaido, Japan during the 1988-1989 eruption. Bull. Volcanol. Soc. Japan, 43, 25-31.

*Ossaka, J., Hirabayashi, J., Nogami, K., Tsuchiide, S. and Adachi, N. (1996) Chemical composition of discolored seawater corresponding to activity of Fukutoku-oka-no-ba submarine volcano. As an index of submarine volcanism. Bull. Volcanol. Soc. Japan, 41, 107-113.

*Ossaka, J., Yamamoto, M., Kurosaki, M., Yoshida, M., Nogami, K. and Hirabayashi, J. (1997a) Change of chemical compositions of fumarolic gases at Unzen spa on the 1990-1995 eruption of Fugen-dake. Jour. Balneol. Soc. Japan, 47, 22-28.

*Ossaka, J., Ossaka, T., Hirabayashi, J., Oi, T., Ohba, T., Nogami, K., Kikawada, K. and Hida, N. (1998b) Water quality changes of Kusatsu hot springs caused by the emergence of Bandaiko hot spring. Bull. Volcanol. Soc. Japan, 47, 166-178.

*Ossaka, J., Ossaka, T., Oi.T., Kikawada, K., Yamano, M., Hukuhara, H., Hirabayashi, J., Ohba, T. and Nogami, K. (1997b) Volcanic activity of Kusatsu-Shirane volcnao, Gunma, and secular change in water quality of crater lake, Yugama. Chikyukagaku, 31, 119-128.

*Oue, K., Ohsawa, S., Yusa, Y. and Kawano, T. (1996) A new chemical geothermometer for strongly acidic hydrothermal water. Jour. Balneol. Soc. Japan, 46, 87-96.

*Oue, K., Ohsawa, S., Nakagawa, R., Takamatsu, N. and Yusa, Y. (1998) Changes in chemical compositions of hot spring water and deposits associated with discoloration of the Chinoike-Jigoku hot pool in Beppu, central Kyushu, Japan. Jour. Balneol. Soc. Japan, 47, 157-165.

Perez, N.M., Nakai, S., Wakita, H., Hernandez, P.A. and Salazar, J.M. (1996) Helium-3 emission in and around volcano, Tenerife, Canary islands, Spain. Geophys. Res. Lett., 24, 3531-3534.

*Saito, G. (1997) A report of the 6th field workshop on volcanic gases. Bull. Volcanol. Soc. Japan, 42, 367-371.

**Sakamoto, H. (1995) Change in the chemical composition of bubble gas from Motiki-Asinage kaigan hot spring: correlation to the activity of Sakurajima volcano (2). Rep. 8th Join Obs. Sakurajima Volc., pp. 71-80.

**Sakamoto, H. (1998) Change in the chemical composition of bubble gas from Motiki-Asinage kaigan hot spring: correlation to the activity of Sakurajima volcano (3). Proc. 9th Int. Symp. Water-Rock Interaction, pp. 101-112.

Sakamoto, H., Tomiyasu, T. and Yonehara, N. (1995) The contents and chemical forms of mercury in sediments from Kagoshima Bay, in comparison with Minamata Bay and Yatsushiro Sea, southwestern Japan. Geochem. Jour., 29, 97-105.

*Sano, Y. (1996) Helium and carbon isotope study on magmatic hydrothermal process at subsurface region. Mem. Geol. Soc. Japan, 46, 83-90.

Sano, Y. and William, S. N. (1996) Fluxes of mantle and subducted carbon along convergent plate boundaries. Geophys. Res. Lett., 23, 2749-2752.

Sano, Y., Takahata, N. and Gamo, T. (1995) Helium isotopes in South Pacific deep seawater. Geochem. Jour., 29, 377-384.

Sano, Y., Gamo, T. and Williams, S. N. (1997) Secular variations of helium and carbon isotopes at Galeras volcano, Colombia. Jour. Volcanol. Geotherm. Res., 77, 255-265.

*Sano, Y., Hirabayashi, J., Ohba, T. and Gamo, T. (1996) Isotopic ratio of carbon and Helium in the fumarolic gases and spring waters around Kusatsu-Shirane volcano. Rep. 3th Join Obs. Kusatsu-Shirane Volc., pp. 73-82.

Sano, Y., Nishio, Y., Sasaki, S., Gamo, T. and Nagao, K. (1998a) Helium and carbon isotope systematics at Ontake volcano, Japan. Jour. Geophys. Res., 103, 23863-23873.

Sano, Y., Takahata, N., Nishino, Y. and Marty, B. (1998b) Nitrogen recycling in subduction zones. Geophys. Res. Lett., 25, 2289-2292.

Sasada, M. and Goff, F. (1995) Fluid inclusion evidence for rapid formation of the vapor-dominated zone at Sulphur Springs, Valles caldera, New Mexico, USA. Jour. Volcanol. Geotherm. Res., 67, 161-169.

Sasaki, M., Iizawa, K. and Sawaki, T. (1995) Characteristics of gases in fluid inclusions from the Nurukawa Kuroko deposit and submarine sulfide deposits of the Izu-Ogasawara arc. Resource Geol., 45, 1-10.

*Sasaki, N. (1997) A hundred year history of the natural monument Hokutolite. Jour. Balneol. Soc. Japan, 47, 115-124.

Seki, Y. (1995) Geochemical characteristics of the Oku-aizu geothermal system, Fukushima, Japan. Proc. 8th Int. Symp. Water-Rock interaction, pp. 543-547.

*Seki, Y. (1996) Geochemical characteristics of the Oku-aizu geothermal system, Japan. Bull. Geol. Surv. Japan, 47, 273-289.

**SEVO (1995) Emission rate of SO2 at Kuju volcano in October, 1995. Rep. Coord. Commit. Pred. Volc. Eruption, 63, 58-59.

**SEVO (1996) Emission rate of SO2 at Kuju volcano (2). Rep. Coord. Commit. Pred. Volc. Eruption, 65, 71-72.

**SEVO (1997a) Emission rate of SO2 at Kuju volcano (3). Rep. Coord. Commit. Pred. Volc. Eruption, 67, 57-58.

**SEVO (1997b) Emission rate of SO2 at Sakurajima volcano. Rep. Coord. Commit. Pred. Volc. Eruption, 67, 76.

**SEVO (1997c) Emission rate of SO2 at Kuju volcano (4). Rep. Coord. Commit. Pred. Volc. Eruption, 68, 78-79.

Shigeno, H., Takahashi, M. and Noda, T. (1995) Gas chemistry for Hijiori hot dry rock circulation tests conducted in 1989 and 1991. Proc. 8th Int. Symp. Water-Rock Interaction, pp. 549-552.

*Shimoike, Y., Notsu, K. and Wakita, H. (1997) Development of a continuous monitoring system of volcanic gas chemistry and its application to the observation at Izu-Oshima volcano. Chikyukagaku, 31, 111-117.

*Shinohara, H. and Kazahaya, K. (1995) Role of volatiles components in eruption processes. Bull. Volcanol. Soc. Japan, 40, S59-S77.

*Shinohara, H. and Hedenquist, J. W. (1997) Constraints on magma degassing beneath the Far Southeast porphyry Cu-Au deposit, Philippines. Jour. Petrol., 38, 1741-1752.

Shinohara, H., Kazahaya, K. and Lowenstern, J. B. (1995) Volatile transport in a convecting magma column: Implications for porphyry Mo mineralization. Geology, 23, 1091-1094.

Strchio, N. C., Areart, G., Ohsawa, S., Kitaoka, K., Yusa, Y. and Sano, Y. (1996) Geochemical characteristics of the Yufuin outflow plume, Beppu hydrothermal system, Japan. Geothermics, 25, 215-230.

Sugisaki, R. and Nagamine, K. (1995) Evolution of light hydrocarbon gases in subsurface processes: constraints from chemical equilibrium. Earth Planet. Sci. Lett., 133, 151-161.

Symonds, R. B., Mizutani, Y. and Briggs, P. H. (1996) Long-term geochemial surveillance of fumaroles at Showa-Shinzan dome, Use volcano, Japan. Jour. Volcanol. Geotherm. Res., 73, 177-211.

**Takahashi, M. (1996) Relationship between formation mechanisms of high and low salinity type of geothermal fluids and Quaternary volcanic activities. Chishitsu News, 502, 48-53.

**Takahashi, M. and Endo, H. (1997) Geochemical survey for hot and mineral springs, related to the 1997 May 11 Sumikawa landslide, Akita prefecture. Chishitsu News, 515, 49-52.

*Takamatsu, N., Oue, K., Ohsawa, S., Kato, N. and Yusa, Y. (1998) Vertical distributions of major, minor and trace elements in a sediment core of Chinoike-Jigoku hot pool in Beppu, central Kyushu, Japan. Jour. Balneol. Soc. Japan, 48, 36-43.

**Takano, B. (1996) Field survey of sulfur compounds in crater lake in Kamchatka. Chishitsu News, 504, 40-47.

**Takano, B. (1997) Inventry of carbon and sulfur in volcanic crater with strong acidic lake water. Gekkan-Chikyu, 18, 64-69.

Takano, B., Matsuo, M. and Suzuki, K. (1995) Bathymetry and chemical investigation of crater lake at Maly Semiachik volcano, Kamchatka. Proc. 8th Int. Symp. Water-Rock interaction, pp. 47-49.

Taran, Y., Fischer, T. P., Pokrovsky, B., Sano, Y., Armienta, M. A. and Macias, J. L. (1998) Geochemistry of the volcano-hydrothermal system of El Chichon volcano, Chiapas, Mexico. Bull. Volcanol., 59, 436-449.

Terakado, Y. and Nakajima, W. (1995) Characteristics of rare-earth elements, Ba, Sr and Rb abundances in natural zeolites. Geochem.Jour., 29, 337-345.

Terakado, Y. and Fujitani, T. (1998) Behavior of the rare earth elements and other trace elements during interactions between acidic hydrothermal solutions and silicic volcanic rocks, southwestern Japan. Geochim. Cosmochim. Acta, 62, 1903-1917.

*Tsuji, H., Yamasaki, Y., Awano, N., Chayama, K., Teranishi, K., Isomura, K. and Ichihashi, K. (1997) Studies of Arima type spring water in Arima spa of Hyogo prefecture. Jour. Balneol. Soc. Japan, 47, 1-13.

**Tsunogai, U. (1997) Carbon isotope measurement of methane plume in ocean. Gekkan-Chikyu, 18, 93-98.

**Tsunogai, U., Ishibashi, J., Wakita, H. and Gamo, T. (1996) Origin of methane dissolved in thermal water discharged during arc magmatisum: comparison of hydrothermal systems on sea floor and subaerial one. Gekkan-Chikyu, 16, 34-39.

**Ueda, A. (1996) Isotope geochemistry of Sumikawa geothermal system. Gekkan-Chikyu, 16, 175-181.

Usui, A. and Mita, N. (1995) Geochemistry and mineralogy of a modern buserite deposit from a hot spring in Hokkaido, Japan. Clay Miner., 43, 116-127.

Usui, A. and Terashima, S. (1997) Deposition of hydrogenetic and hydrothermal manganese minerals in the Ogasawara (Bonin) arc area, northwest Pacific. Mar. Georesources Geotechnol., 15, 127-154.

Watanabe, S., Tsurushima, N., Tsunogai, S. and Kusakabe, M. (1995) Methane in Izena cauldron, Okinawa trough. Jour. Oceanogr., 51, 239-255.

Xu, S., Nakai, s., Wakita, H. and Wang, X. (1995) Mantle derived noble gases in natural gases from Songliao Basin. Geochim. Cosmochim. Acta, 59, 4675-4683.

Yamamoto, K. (1995) Gold deposits of the Seta area, Kamishihoro town,eastern Hokkaido, Japan. Mining Geol., Spec. Issue 18, 249-256.

*Yamamoto, M., Koike, T., Masui, F., Shiota, A., Tsurita, H., Ohtsuka, A., Nogami, K. and Ossaka, J. (1997) Isotope geochemistry of hot spring waters on the eastern side of Kusatsu-Shirane volcano, Gunma prefecture, Japan. Jour. Balneol. Soc. Japan, 47, 68-75.

*Yamano, M., Ossaka, T., Oi, T. and Ossaka, J. (1995) Contents of halide ions of hot spring waters in the Kusatsu-Shirane volcano area. Jour. Chem. Soc. Japan, 8, 656-659.

Yamashita, S., Kitamura, T. and Kusakabe, M. (1997) Infrared spectroscopy of hydrous glasses of arc magma compositions. Geochem. Jour., 31, 169-174.

*Yanagisawa, T. (1997) Tamagawa hot spring and radioactivity. Jour. Balneol. Soc. Japan, 47, 98-103.

Yokoyama, T., Nakao, S., Sugioka, H., Hayashi, S. and Izawa, E. (1996) Determination of gold in geothermal water by anion exchange and inductively coupled plasma mass spectrometry. Geochem. Jour., 30, 183-187.

*Yusa, Y. (1996) Origin of hot spring, with reference to origin of chlorine. Jour. Balneol. Soc. Japan, 46, 105-108.

(* In Japanese with English abstract. ** In Japanese)