Free Air and Bouguer Gravity Anomaly in the West Pacific Calculated from Sea Gravity Data Obtained by T. S. S. G.(1963-1980)

Abstract

Sea gravity data obtained by use of T . S . S . G. in the west Pacific in the years 1963-1980 are compiled and maps of free air and Bouguer gravity anomaly were made. Gravity anomalies in the west Pacific, especially in the east part, are characterized by gravity high at seamount, gravimetric root around seamount, low gravity anomaly at trench, outer gravity high seaward of trench, and mutual interaction between sea amounts and trenches. Gravimetric and seismic results show that two kinds of seamount exist. One can easily subduct at the trench, in which case the seamount is supported by buoyancy of asthenosphere, and the other one cannot subduct easily because the seamount is supported by buoyancy of the crust.