Constraints on Transient Viscoelastic Rheology of the Asthenosphere From Seasonal Deformation

Kristel Chanard, Luce Fleitout, Eric Calais, Sylvain Barbot, Jean Philippe Avouac

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)


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 × 1017 Pa.s, suggesting that low values of transient asthenospheric viscosities reported in some postseismic studies cannot hold for the seasonal deformation global average.

Original languageEnglish
Pages (from-to)2328-2338
Number of pages11
JournalGeophysical Research Letters
Issue number5
Publication statusPublished (in print/issue) - 16 Mar 2018


  • asthenosphere
  • loading
  • postseismic
  • seasonal
  • transient viscosity
  • viscoelastic


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