Abstract
R. G. A. (Residual Gravity Anomaly) was calculated along a section across the Hawaiian Ridge near Oahu Island by use of both the gravity data and the crustal velocity structure obtained by the explosion seismology. Anomalies of lithospheric thickness in this region were estimated from the result of the calculation of R. G. A. It is concluded that the thickness of lithosphere beneath the island is about 20k mthinner than that beneath the surrounding area as expected from the lithospheric thinning model.
The values of R. G. A. in the Emperor Seamount Chain are smaller than those in the Hawaiian Region obtained in this work, so the thinner lithosphere beneath the seamount approaches the normal state with increasing the age of the seamount in the Hawaiian-Emperor Seamount Chain. This agrees with the lithospheric thickening model.
