Mean Density of Mt. Fuji as Determined from the Intensity of Gravity at its Summit (II)

Abstract

In the previous paper (I), the present authors calculated the vertical attraction Am of Mt. Fuji at the summit stations S₁ and S₂ taking into account the exact form of the mountain. The values of A, n thus obtained are 105.37, 0 mgal for the station S₁ and 105.02, 0 mgal for S₂, where p is the mean density of the mountain under consideration. In this paper, value of Am is deduced from the gravity value obtained by Mendenhall at the summit, and, combining this value of Am with the result mentioned above, the value of pis calculated. The calculation should be made in consideration of the vertical attraction, C+A, at the summit station, due to the subterranean mass anomalies which may be expected from the theory of isostasy and subsurface geologic structure. Disregarding the effect of C*+A, the mean density of the mountain is 1.75 or 1.78, which seems to be too small. An approach to the estimation of C+A at the summit stations would be made possible by utilizing the already published data of Bouguer anomalies at Kofu, Shizuoka, Numazu and Odawara situated around and near the mountain, and the vertical gradients of gravity at these stations, which will be easily determined if we make use of a Worden gravity meter.