Nature, 387, 169-173, 1997.
Changes of the Earth's rotation axis owing to
advection of mantle density heterogeneities:
Bernhard Steinberger and Richard J. O'Connell
Abstract:
Polar wander, the secular motion of the Earth's rotation axis
relative to its surface, has been of interest for many years. Dynamical
arguments show that the redistribution of mass in a plastic,
deformable Earth can lead to polar wander; the rate depends on both the
rate of mass redistribution and the rate at which the Earth's
rotational bulge can readjust to the changing rotation axis. Here we
use a viscosity structure obtained through geoid modeling, a
mantle flow field consistent with tomographic anomalies and
time-dependent lithospheric plate motions to calculate advection
of mantle density heterogeneities and corresponding changes in the
degree two geoid during the Cenozoic. We show that the rotation axis
will follow closely any imposed changes of the axis of maximum
non-hydrostatic moment of inertia. The resulting path of the rotation
axis agrees well with paleomagnetic results. The model predicts a
current rate of the polar motion that is a significant fraction (40%)
of that observed geodetically.
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