3. Gravity Measurements Near Japan and Study of the Upper Mantle Beneath the Oceanic Trench-Marginal Sea Transition Zones

  1. George H. Sutton,
  2. Murli H. Manghnani,
  3. Ralph Moberly and
  4. Ethel U. Mcafee
  1. Jiro Segawa and
  2. Yoshibumi Tomoda

Published Online: 17 MAR 2013

DOI: 10.1029/GM019p0035

The Geophysics of the Pacific Ocean Basin and Its Margin

The Geophysics of the Pacific Ocean Basin and Its Margin

How to Cite

Segawa, J. and Tomoda, Y. (1976) Gravity Measurements Near Japan and Study of the Upper Mantle Beneath the Oceanic Trench-Marginal Sea Transition Zones, in The Geophysics of the Pacific Ocean Basin and Its Margin (eds G. H. Sutton, M. H. Manghnani, R. Moberly and E. U. Mcafee), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM019p0035

Author Information

  1. Ocean Research Institute, University Of Tokyo, Tokyo 164, Japan

Publication History

  1. Published Online: 17 MAR 2013
  2. Published Print: 1 JAN 1976

ISBN Information

Print ISBN: 9780875900193

Online ISBN: 9781118663592

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Keywords:

  • Geophysics—Pacific area—Congresses;
  • Woolard, George Prior, 1908

Summary

A free-air gravity anomaly map of Japan and the surrounding seas is presented, compiled primarily from data obtained by the Tokyo Surface Ship Gravity Meter. By use of gravity and the presently available seismic refraction data obtained for the crustal structures, the density anomalies in the upper mantle near the Japan and Izu-Bonin arcs have been estimated. Plausibilities of the densityanomalies thus obtained have been examined by comparing them with the results from anomalous seismic velocities and density-velocity relationships. The residual gravity anomalies near oceanic trenches, which have been considered to be discordant with seismic results, have been estimated as accurately as possible, and then explained in terms of a concentration of mass within a bending lithosphere due to possible elastic compression, phase transformations, or magmatic flows.