  The variation in the figure axis in the Earth owing to the geophysical causes
directly reflects the physical state of the Earth and therefore, it is
important for understanding the Earth. Of the variations in the figure axis
arising from different causes, the variation owing to the Earth's geophysical
causes is determined from polar motion data. Equations that give the relation
between the figure axis and rotational axis are derived and the motion of the
figure pole with respect to the Earth's surface or the figure axis in the Earth
is determined by using these equations. Estimation of error suggests that the
accuracy of the determination for the position of the figure pole at each
moment is sufficiently good and that even a variation that occurs during a
short duration of time, such as one or two days, is significant. The determined
position of the figure pole exhibits a rapid and complicated motion in a short
duration. On the other hand, a long-range average of the pole shows stable
annual and semi-annual variations, but it is quite independent of the Chandler
wobble.
