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Constraints on Transient Viscoelastic Rheology of the Asthenosphere From Seasonal Deformation

Chanard, Kristel and Fleitout, Luce and Calais, Eric and Barbot, Sylvain and Avouac, Jean-Philippe (2018) Constraints on Transient Viscoelastic Rheology of the Asthenosphere From Seasonal Deformation. Geophysical Research Letters, 45 (5). pp. 2328-2338. ISSN 0094-8276. doi:10.1002/2017GL076451.

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We discuss the constraints on short‐term asthenospheric viscosity provided by seasonal deformation of the Earth. We use data from 195 globally distributed continuous Global Navigation Satellite System stations. Surface loading is derived from the Gravity Recovery and Climate Experiment and used as an input to predict geodetic displacements. We compute Green's functions for surface displacements for a purely elastic spherical reference Earth model and for viscoelastic Earth models. We show that a range of transient viscoelastic rheologies derived to explain the early phase of postseismic deformation may induce a detectable effect on the phase and amplitude of horizontal displacements induced by seasonal loading at long wavelengths (1,300–4,000 km). By comparing predicted and observed seasonal horizontal motion, we conclude that transient asthenospheric viscosity cannot be lower than 5 × 10^(17) Pa.s, suggesting that low values of transient asthenospheric viscosities reported in some postseismic studies cannot hold for the seasonal deformation global average.

Item Type:Article
Related URLs:
URLURL TypeDescription
Chanard, Kristel0000-0001-9934-9621
Fleitout, Luce0000-0003-1114-3616
Calais, Eric0000-0002-5935-8117
Barbot, Sylvain0000-0003-4257-7409
Avouac, Jean-Philippe0000-0002-3060-8442
Additional Information:© 2018 American Geophysical Union. Received 18 NOV 2017; Accepted 7 FEB 2018; Accepted article online 12 FEB 2018; Published online 15 MAR 2018. This work benefits from gravity data processed by the CNES/GRGS ( and of GNSS data processed by the Nevada Geodetic Laboratory ( This work was partially supported by NSF grant EAR‐1345136, the Laboratorie de Recherche Commun “Yves Rocard” (ENS‐CEA‐CNRS), and CNRS/TOSCA grant 2925. We thank Matt King and one anonymous reviewer for providing useful comments and help improving this manuscript.
Group:Seismological Laboratory
Funding AgencyGrant Number
Commissariat à l’Energie Atomique (CEA)UNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)2925
Subject Keywords:viscoelastic; loading; asthenosphere; transient viscosity; postseismic; seasonal
Issue or Number:5
Record Number:CaltechAUTHORS:20180411-105832773
Persistent URL:
Official Citation:Chanard, K., Fleitout, L., Calais, E., Barbot, S., & Avouac, J.‐P. (2018). Constraints on transient viscoelastic rheology of the asthenosphere from seasonal deformation. Geophysical Research Letters, 45, 2328–2338.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85745
Deposited By: Tony Diaz
Deposited On:11 Apr 2018 18:29
Last Modified:15 Nov 2021 20:31

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