Crustal Structure under the Kanto Plain and Its Relation to Tectonics

Abstract

Studies of the crust and upper mantle structure in and around the Kanto Plain was reviewed. It has been revealed that the crust under the Kanto Plain has no distinct granitic layer and that the crust and the upper mantle under the southern half of the Kanto Plain is the Philippine Sea Plate which is subducting under the North American Plate. It is supposed that the anomalous crustal structure, i.e., lack of the granitic layer, is a cause of low activity of shallow earthquake under the Kanto Plain. The tearing of the Philippine Sea Plate under the Tokyo Bay is considered to be the cause of the occurrence of destructive earthquakes in the metropolitan Tokyo.