Gravity Anomalies and the Crust-mantle Structure in Japan

Abstract

Most probable depth of the Moho discontinuity in Japan is determined mainly from the gravity analysis. Comparison of the results with other inferences from explosion and surface wave studies indicates the lower value of P and S waves in the upper mantle in Japan. This reduction in the seismic wave velocity may be attributed either to increase in the Poisson's ratio due to the temperature effects or to elastic anisotropy of rock-forming crystals which must await further studies.