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Transient polar motions and the nature of the asthenosphere for short time scalesA uniformly valid mathematical formalism is developed to study the secular motions of the rotational axis of a layered viscoelastic earth due to seismic excitation. The changes required for implementing the formulation within the framework of the faulting problem. The rationale of adopting the chosen nrheological model, which contains a low-viscosity zone beneath the lithosphere and is based on linear Maxell constitutive relationship, is discussed. The impact of this low-viscosity channel on thhe two families of relaxation time, governing both isostatic readjustment and rotational processes, is considered. It is found that the polar motions depend sensitively on the viscosity structure of the asthenosphere and not at all on the underlying mantle. A gloal low-velocity zone with short-term asthenospheric viscosities less than about 5 x 10 to the 18th Pa-s and widths greater than 50 km is ruled out.
Document ID
19850048376
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Boschi, E.
(Istituto Nazionale di Geofisica, Rome; Bologna, Universita Bologna, Italy)
Sabadini, R.
(Bologna, Universita Bologna, Italy)
Yuen, D. A.
(Colorado, University Boulder, CO; Arizona State University, Tempe, AZ, United States)
Date Acquired
August 12, 2013
Publication Date
April 10, 1985
Publication Information
Publication: Journal of Geophysical Research
Volume: 90
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
85A30527
Funding Number(s)
CONTRACT_GRANT: NSF EAR-82-14094
CONTRACT_GRANT: NAG5-400
CONTRACT_GRANT: NSF EAR-81-17439
Distribution Limits
Public
Copyright
Other

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