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1960 Chile: New estimate of polar motion excitation
Author(s) -
Slade M. A.,
Yoder C. F.
Publication year - 1989
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl016i010p01193
Subject(s) - polar motion , excitation , polar , context (archaeology) , geodesy , geology , seismology , geophysics , physics , earth's rotation , astronomy , paleontology , quantum mechanics
A recent reanalysis of the ILS polar motion data has been processed using Kalman filtering techniques to generate the polar motion excitation function over the time‐span from 1960 to 1965. The resulting excitation function has been examined for the effects of 1960 Chile in an attempt to determine experimentally how large earthquakes affect polar motion. The examination was deliberately not placed in the context of any theory of seismic or postseismic excitation. The resulting upper bound of ∼75. × 10 22 N‐m. for a 10° dip (∼36. × 10 22 N‐m for 20° dip) is consistent with results obtained from previous seismic studies, including a recent normal mode excitation result. Following future great earthquakes, monitoring of polar motion by space‐based techniques such as VLBI should continue at high temporal resolution for several weeks in order to directly measure the rheological parameters of the upper mantle.