八丈島・鳥島における重力測定
1964 年 10 巻 1 号 p. 24-35
詳細
1964 年 10 巻 1 号 p. 24-35
Gravity observations were carried out by the Geographical Survey Institute in Hachijo and Torishima islands with gravimeter as a part of the synthetic geophysical investigation about Idzu-Mariana arc island in March and April, 1963. This works are separated into two parts. The one is to establish a precise fundamental gravity station in each island refered to Tokyo, G. S. I. The results are; g Hachijo-g Tokyo, G. S. I.= -39.25±0.02(m. e.) mgals (with Worden gravimeter No. 346 and La Coste and Romberg gravimeter G-29) g Torishima-g Tokyo, G. S. I.= -234.09±0.04(m. e.) mgals (with La Coste and Romberg gravimeter G-29) The other is to find the general trend of the distribution of the gravity anomalies in each island and this was performed with the one way observation method by a gravimeter. Also the observations of the vertical gradient of gravity were made at some places in both island. One of the remarkable results of the observation in Hachijo was to find a relatively negative gravity anomaly at the center of Higashiyama caldera.
