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Large earthquakes and Earth rotation: The role of mantle relaxation
Author(s) -
Soldati Gaia,
Spada Giorgio
Publication year - 1999
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 - 10.1029/1999gl900144
Subject(s) - geology , mantle (geology) , asthenosphere , geophysics , earth's rotation , induced seismicity , polar motion , lithosphere , mantle convection , moment of inertia , seismology , geodesy , tectonics , physics , quantum mechanics
By means of a radially stratified spherical model and using the available moment tensor solutions, we evaluate the contribution of large earthquakes to polar drift in the last two decades. In contrast to previous analyses, which only considered the elastic response of the Earth to the release of seismic moment, we account for mantle rheology and thus for the time‐dependent postseismic inertia changes driven by global seismicity. We confirm that during the last twenty years the global seismic activity has not significantly altered the rotational parameters of the Earth. However, we find that for values of asthenospheric viscosity suggested by recent studies of postseismic stress diffusion, the delayed relaxation of the mantle amplifies the average rate of polar drift by a factor of 1.2 to 1.7 (depending on the width of the asthenosphere) even on a decade time‐scale.