Excel spreadsheet containing all benchmark parameters and data, model setup information, and mode... more Excel spreadsheet containing all benchmark parameters and data, model setup information, and model results. (XLSX 180 kb)
The degree of anisotropic viscosity and the grain size of upper mantle minerals are two important... more The degree of anisotropic viscosity and the grain size of upper mantle minerals are two important rheological parameters that influence the dynamics of flow in the mantle. Both parameters, however, are generally poorly constrained. We use numerical models of asthenospheric flow to determine the grain size and anisotropic viscosity required to explain the observed confinement of seismic anisotropy to a layer at the top of the convecting upper mantle. We find that a grain size larger than 10mm gives the best fit to the observations. The ratio of shear viscosity to normal viscosity is 0.3 or higher (less anisotropic), depending on the grain size. Width of the layer in the upper mantle which exhibits sufficient shear strain to present seismic anisotropy, plotted as a function of the grain size and the magnitude of anisotropic viscosity (ratio between shear to normal viscosities).
Excel spreadsheet containing all benchmark parameters and data, model setup information, and mode... more Excel spreadsheet containing all benchmark parameters and data, model setup information, and model results. (XLSX 180 kb)
The degree of anisotropic viscosity and the grain size of upper mantle minerals are two important... more The degree of anisotropic viscosity and the grain size of upper mantle minerals are two important rheological parameters that influence the dynamics of flow in the mantle. Both parameters, however, are generally poorly constrained. We use numerical models of asthenospheric flow to determine the grain size and anisotropic viscosity required to explain the observed confinement of seismic anisotropy to a layer at the top of the convecting upper mantle. We find that a grain size larger than 10mm gives the best fit to the observations. The ratio of shear viscosity to normal viscosity is 0.3 or higher (less anisotropic), depending on the grain size. Width of the layer in the upper mantle which exhibits sufficient shear strain to present seismic anisotropy, plotted as a function of the grain size and the magnitude of anisotropic viscosity (ratio between shear to normal viscosities).
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