Hot springs in Japan are divided into three groups which are distributed respetively in younger volcanic, semi-volcanic and non-volcanic areas, according to the relation of younger volcanic zones to hot springs. On the other hand, hot springs are classified into two types, namely the one high in Cl' content and the other moderate. Hot springs characterized by high content of Cl' derived from aqueous or igneous origin are situated in tertiary oil fields, tertiary volcanic or hypabyssal rock areas and granite areas. The following phenomena recognized in thermal areas are important to know properties of hot springs distributed in younger volcanic areas : (1) Volcanic gases are higher in content of HCl than fumarolic gases. (2) Hot springs emitted from fumarolic areas are divided into two types, the one is saline water type characterized by higher content of Cr and the other is ground water type by lower of Cl' in ground water. (3) According to the abundance of Cl' content in thermal areas, there are two types of hot springs in the centre of thermal activity of altered rock areas. One is the type showing high content of Cl', the other is low. The above-mentioned phenomena are considered to depend upon the diffusing flow of volcanic or fumarolic gases through the mother rocks and the depth of circulating ground water. Accordingly, it is probable that HCl contained in volcanic gases is not only dissolved in deep vadose water, but also fixed as halide salts in the wall rocks on the way up to the surface from a volatile source. Properties of hot springs of such a various range from acidic to alkaline, distributed in younger volcanic areas seems to be influenced by shallow volcanic or fumarolic action in addition to the diffusing flow of volcanic or fumarolic gases and the ascending distance of thermal water to the surface.
1. Obama hot springs, situated on the east coast of Shimabara peninsula, Nagasaki prefecture, are now prosperously utilized for the salt-making industry, and its daily consumption of hot water (9°C-100°C) amounts 60, 000t containing the heat energy 4.6 × 109 kcal (equivalent to 750 ton coal). This amount in much excess discharge against the capacity of heat and the transfering velocity, of hydrothermal solutions. 2. Consequently, there have provoked much serious accidents, that is, the areal retrenchment of flowing zone, the fall of the rock temperatune (20°C at the bottom of the bore hole) and others. For these troubles, the temporary restriction of discharge has put in operation, and the recovery indications are now percieved. 3. Analysing these supercritical phenomena, the writer has presumed the dimensions, energies in the order estimating calaulations. The results are as follows : (a) heat energy of this magma 0.26 × 1014 Kcal (b) dimension of this magma 0.06 Km3 (a sphere with 200m radius) 4. From the geochemical point of view, there are very much interesting facts concerning the relation among sea water, ground water, and hydrothemal solutions. The spring water has recently the content of 12, 000 p. p. m. Cl' that is above two-fold of the older spring water. Table 4 shows the ultimate answer about this problem. Potash and silica rich solution is normal in such a condition as alkaline. The juvenile water ratio of this hot spring is as follows : Juvenile water vadose water The older spring 67% 33% The present spring 15% 85% Therefore its natural steam is too wet and faint for the electric power engineering.
The Tsuruno-yu hot spring was sunk in the reservoir (Okutama lake). But it was reconstructed on the lakeside before that time. The writers found the spring source by the invesitgative tunnel on the left reach of the Tama river, and the hot spring was gathered by the boring (44 holes) in that tunnel. The temperature of this spring is 31.2°C, and its flow is 320 l/mim. On the other hand, it was connected between the lakeside and the boring points with the humepipe which is set in the tunnel and the vertical shaft. The hot spring was carried in the humepipe to the vertical shaft, and after then it pumped up to lakeside by the submersible-motor pump. It is closely related to the level of hot spring (A) in the vertical shaft and the water level of reservoir (B). Always, the level of hot spring is higher than the water level of reservoir. As the ascent of the descent of the water level of reservoir, the level of hot spring become of the same conditions too. As the ascent of the water level of reservoir, it decreases the value of A-B, and on the contray, as the descent of the water level of reservoir, it increases the value of A-B.
In the western district of the Northern Alps of Japan, the Tetori groups are scattered, each in rather small area on the high mountains, such as Yakushi-dake, Kitanomata-dake, Kurobegoro-dake and others. In this paper the writer treats especially the group in the Kitanomata-dake area. The area is covered mainly by the Oritate-toge conglomerate, which is the basal one of the Itoshiro subgroup occupying the middle division of the Tetori group and is composed of the rounded pebbles of granite, gneiss, quartz-porphyry, cherty rocks, sandstone, hornfels and so on. The conglomerate along the upper drainage of the Kitanomata River, forming a monoclinic structure, is a southeastern part of the large basin structure situating in the southern district of Toyama Prefecture. On the eastern margin of this basin, the conglomerate unconformably overlies the basement of the Shimonomoto-type granitic rocks which intruded in late Palaeozoic, whereas on the southeastern margin is normal fault contact with the plutonic rocks of the same type. In the valley of the Kitanomata River the fossil plants are found, such as Cladophlbis exiliformis (Geyler), Onychiopsis elongata (Geyler), Podozarnites lanceolatus (Lindley and Hutton) and Xenoxylon latiporosum (Gramen), the discovery of the last of which is significant of its extensive distribution on the Tetori group.