1985 年 94 巻 6 号 p. 445-454
The hole with the depth of 150 m was drilled at Motoyama area. From ground surface to the depth of 24.7 m, pyroclastic rock was found, and trachy andesite was found under the pyroclastic rock. Beneath these, additional two units of this type were recognized. The temperature at the bottom of the hole was 167 °C. According to electrical logging, under the sea level, the self-potential was changed from possitive to negative, and the resistivity index was about zero.