Tides and nutation of the earth: I. Models of an earth with an inelastic mantle and homogeneous,inviscid, liquid core

The use of very-long-baseline radio interferometers during the past 10–15 years has increased the accuracy of amplitude measurements of the Earths forced nutation by more than two orders of magnitude (from 3–5 arc ms to 20 arc s). At the same time, cryogenic gravimeters (which depend for their action on the repulsion of two superconductive rings in a gravitational field) have made it possible to also improve the accuracy of measurements of tidal variations in the gravitational force by two orders of magnitude. This opens up new avenues for the investigation of the mechanical properties of the Earths interior at ultralow frequencies. A brief review is given here of the basic results of interpreting astrometric data and measurements of tidal variations in the gravitational force. Problems suggested by the new observational techniques are formulated.Translated from Astronomicheskii Vestnik, Vol. 38, No. 6, 2004, pp. 542–558.Original Russian Text Copyright © 2004 by Molodensky.