Deformation of the Earth's Crust in the Tempoku-Urakawa Zone

Abstract

It is the well known fact that notable relations exist between the distribution of Bouguer gravity anomalies and the structural units of the surface geology in Hokkaido, which have been formed by the orogenic movements since the Miocene period. For example, the Hidaka mountains which have been violently upheaved in the most recent geologic age, are areas of remarkably high gravity while the Tempoku-Urakawa Zone which have rapidly subsided in the same age is the area of strong negative anomalies running parallel to the mountains. In this paper, it is shown that the pattern of the strong negative anomalies of the Tempoku-Urakawa Zone can be explained by Vening Meinesz's theory of visco-elastic deformation of the crust by compressive stress. Time required for the deformation of the crust and density of sedimentary layer was also calculated and these results are in good harmony with the geohistorical evidence in this region. © 1962, The Geodetic Society of Japan. All rights reserved.