本州中部地域のアイソスタシー
1984 年 37 巻 4 号 p. 569-578
詳細
1984 年 37 巻 4 号 p. 569-578
Isostasy over central Honshu area is examined by the following four methods.
(1) Cross-spectrum technique is applied to analyse a correlation between Bouguer anomalies and topographic relief over the area. Admittance functions derived from this technique for the area show good agreement with those for stable continents.
(2) Residual Bouguer anomalies (R. B. A.) over the area are calculated by subtracting a gravity effect of the subducting Philippine sea plate from the observed Bouguer anomalies. The relationship between the R. B. A. and topographic releaf shows a higher correlation than that between the observed Bouguer anomalies and topographic relief.
(3) Theoretical Bouguer anomalies calculated by using the admittance functions in central Honshu and topographic relief in stable continents are in good agreement with the R. B. A. over the area.
(4) Hydrostatic pressure at the Moho along the Atsumi-Noto explosion seismological observation line satisfies the empilical rule between depth of Moho and pressure at it, which was found in tectonically stable continental and oceanic areas.
It is shown from these results that the isostatic state is achieved over central Honshu as it does over stable continents, though the area is tectonically quite active.
