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Polar motion, 1994-1997
Solid line : mean pole displacement, 1900-1996.


International Earth Rotation Service

*The numbers 1935, 1950, & 1960 were added by MW Mandeville from extrapolation with other charts


The Y Axis is longitude, 80 degrees W. The North Axis is "drifting" south approximately down longitude 80 degrees west. Or, North America is slowly drifting up longitude 80 towards the North Axis. Since 1935, the "true mean" axis has moved nearly .4 arcseconds.

This is a long term secular trend. It is true polar wander in addition to the normal randam fluctations caused by strong winds, earthquakes, ocean tides, other unknown variables, and of course, the normal "Chandler Wobble" and Precession of the Equinox. Scores of geophysicists have been studying the measuring techniques, the mathematical formulas, and the results since the 1950's. They are very certain that the exact location of the axis of the earth is highly sensitive to winds, tides, earthquakes, and changes in the distribution of mass in or on earth. And they are very certain that the axis of the earth is progressively "tilting".

Notice the marked shift in the direction of the axis between 1935 and 1940. In 1932, Edgar Cayce predicted that the earth in 1936 would change its axis position in response to some change inside the earth induced by "outside forces". This chart clearly proves Cayce correct.

Notice the change in direction at approximately 1950 and the slow steady creep back to the "Y" baseline at 1960. Notice the jag just past 1960, which very likely reflects the 1964 Alaska Earthquake which caused an uplift of half of the North American continent. Cayce predicted in the early 1930's that long term "earth changes" would commence in 1958 and intensify in 1998 as "omens" of a major shifting of the pole. This chart is chillingly consistant with that prediction. Other predictions made by Cayce about the long term earth changes prove Cayce correct.

Without question, this chart shows that the Phoenix is already taxiing of the runway...and demonstrates the delicate poise of the earth's orientation in space. The dashed lines show the regular "Chandler's Wobble", except that Chandler's Wobble is not nearly so smooth as you might think. The various dents and shift of the circle from year to year in what should be a perfect circlar shape are caused by solar and lunar tides, winds, shifts in the earth's mass (earthquakes) and unknown factors.

This chart was prepared by the The International Earth Rotation Service (IERS) which is an interdisciplinary service that maintains key connections between astronomy, geodesy and geophysics.The global observing effort involves Very Long Baseline radio Interferometry (VLBI), Lunar Laser Ranging (LLR) and several satellite tracking techniques: Global Positioning System (GPS), Satellite Laser Ranging (SLR) and DORIS (Doppler Orbit determination and Radiopositioning Integrated on Satellite), all based on worldwide networks totalling over 300 sites.

The terrestrial reference system established by the IERS is recommended by the International Association of Geodesy and the International Union of Geodesy and Geophysics as the International Terrestrial Reference System (ITRS). IERS is in charge of its maintenance.

The analyses of the observational data provide rapid service and long-term monitoring of the Earth's orientation, as well as the determination of crustal motions and other dynamical parameters. The Earth rotation and reference frame results compiled and distributed by IERS are accurate at the level of +/-0.3 milliarcseconds , corresponding to 1 cm on the surface of the Earth.

The major Earth system fluid components, namely the atmosphere, ocean, and the core are known to participate in forcing motions of the Earth, including Earth rotation and polar motion, and to modify the gravitational fields and the motions of the Geocenter.This is why the IERS extends its activities to the Monitoring of Global Geophysical Fluids in order to help relate properties of the various global geophysical fluids to motions of the Earth, including those of its three-dimensional rotation vector.

Copyright 1997, Trudy Weddington, all rights reserved

Last Revision: January 16, 1997