大島における重力変化の研究(II)
1972 年 18 巻 3 号 p. 104-111
詳細
1972 年 18 巻 3 号 p. 104-111
Since 1963, the Geographical Survey Institute has been engaged in gravity observations in Ooshima Island, one of the most active volcanoes in Japan. This is the second report and gives the results of observations made in 1969 and 1972. At Gojinka Chaya, very close to the crater of Mt. Miharayama, we have six gravity values obtained at different period. By comparing these values, it is proved that gravity at Gojinka Chaya was gradually decreased after the great eruption of 1950 till 1967. This decrease reaches to 0.9 mgal. During the period from 1967 till now gravity begins to increase by 0.1 mgal. The authors emphasize the importance of repeated gravity observations also in future in order to get useful informations about volcanic activities in this volcano.
