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Features of the Chandlerian Nutation

Published online by Cambridge University Press:  25 April 2016

H. J. M. Abraham
H. J. M. Abraham*
Affiliation:
Formerly Mount Stromlo and Siding Spring Observatories, Research School of Physical Sciences, The Australian National University, Canberra, Australia
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Abstract

Reported data on the Chandlerian nutation show that there are irregular yet related changes in the rate of energy gain, the damping and the phase, changes which were remarkably great in the late 1920s. Dynamical interpretations need a model that has friction elements as well as springs and dashpots; it then offers further applications as well; e.g. to a correlation between reported values of the Love number k and tidal potentials. The model is used in discussing the increases in amplitude and the advances in phase; the short and long-term rates of energy gain and their interruptions and damping; the correlation between short Chandlerian periods and large amplitudes in the annual nutation; and the correlation between damping and the apparent frequency. Doubts are expressed about nutational values of Q. A geophysical interpretation of the model is obtained from seismic data. It was found that every large rise in the nutational energy was preceded by an earthquake in the Andes region; and that the secular rate of energy gain varied with the circum-Pacific seismicity. Decreases in these were accompanied by rises in the Earth’s rotational acceleration and were followed by deep earthquakes in a diminishing region east of the Andes. It appears that the nutational and seismic events are due to tectonic stress, and intermittently this is relieved by subduction.

Type
Contributions
Information
Publications of the Astronomical Society of Australia , Volume 6 , Issue 4 , 1986 , pp. 416 - 424
Copyright
Copyright © Astronomical Society of Australia 1985

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