The structual anomaly beneath the Kirisima-Sakurazima volcanoes estimated from P wave velocity is concerned. The travel time residuals O-C at KVO (Kirisima Volcano Observatory, a branch station of Earthquake Research Institute) are discussed using intermediate earthquakes beneath the Kyushu-Ryukyu arc (Figs. 1 and 2). The Jeffreys-Bullen and Ichikawa-Mochizuki travel time tables are used for the calculation of arrival times. The flat layered model obtained from surface wave analyses is also used (Fig. 3). A clear discrepancy between O-C of earthquakes in south and in north at KVO is found. O-C from soutn at KVO is +1～2 seconds and few seconds larger than from north (Fig. 4). This positive anomaly of O-C means that P wave velocity beneath the Kirisima-Sakurazima volcanoes is smaller than that beneath the north part of Kirisima. There are two reasons to suspect that the low P wave velocity occurs not in the crust but in the upper mantle; 1 (O-C from only south is positive anomaly in spite of the fact that the incident angle at KVO is larger than 70 degrees (see Fig. 4), 2) O-C of earthquake with the depth of 160 km is larger than that with 120～130 km.

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The isotopic and chemical composition of neutral chloride thermal waters (≦100℃) tapped by drillholes at Atagawa, Katase-Shirada, Inatori, Mine and Yazu, Izu p eninsula, Japan, together with neutral sulfate thermal waters (37°～63℃) from Otaki, Yugano, Kochi and Rendaiji hot springs, Izu, have been determined. The isotopic and chemical data suggest that the deep chloride thermal waters are derived from the mixture of local surface water and sea water. Sulfate ion could be derived from the anhydrite deposited in the Yuga-shima formation (common country rock of the thermal waters examined). Sulfate concentration in the thermal waters is limited by the solubility of anhydrite at the bottom of drillholes, except at Mine and Yazu. The behavior of sodium, potassium and calcium ions is also controlled by thermal water-rock equilibria.

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Measurements of mass flow of SO₂ at Asama Volcano were carried out by means of a Barringer correlation spectrometer on April 28, 1974, one year after the eruptive activity. The spectrometer was carried on the Jeep and the scanning was made with its telescope directed vertically along the drive way which runs eastward of the volcano. The wind velocity at the relevant altitude was measured with pilot ballons. Several runs of measurement syielded the total emission of SO₂ from the summit crater as 780 tons/day. Comparing with the previous value (142 tons/day) in June, 1972, SO₂ emission increased remarkably probably as the consequence of the recent eruptive activity. Global discharge of SO₂ to the atmosphere is evaluated as 3×10⁷ tons per year. From the volcanological point of view, one of the essential problem is to estimate the bulk discharge of H₂O from the individual volcano. If we carry out the similar observation at a volcano where the mole ratio of H₂O/SO₂ is known, we can evaluate the total emission of H₂O and consequently the thermal energy transported by H₂O from a volcano may be estimated.

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