Global plate tectonics and the secular motion of the pole
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Date
1977-02
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Publisher
Ohio State University. Division of Geodetic Science
Abstract
Astronomical data compiled during the last 70 years by the international organizations (ILS-IPMS, BIH) providing the coordinates of the instantaneous pole, clearly shows a persistent drift of the "mean pole" ( barycenter of the wobble). This study was undertaken with a specific objective in mind: to investigate the possibility of a true secular motion of the barycenter; that is, an actual movement of the earth pole of figure resulting from differential mass displacement due to lithospheric plate rotations. The method developed assumes the earth modeled as a mosaic of 1° x 1° crustal blocks, each one moving independently in accordance with their corresponding absolute plate velocities. The differential contributions to the earth's second-order tensor of inertia were obtained and applied, resulting in no significant displacement of the earth's principal axis. In view of the above, the effect that theoretical geophysical models for absolute plate velocities may have on an apparent displacement of the "mean pole" as a consequence of station drifting was analyzed. The investigation also reports new values for the crustal tensor of inertia (assuming an ellipsoidal earth) and the orientation of its axis of figure, reopening the old speculation of a possible sliding of the whole crust over the upper mantle, including the supporting geophysical and astronomic evidence.
Description
Prepared for National Aeronautics and Space Administration, Washington, D.C.: Grant No. NGR 36-008-204, OSURF Project No. 3820-A1