Mathematics – Logic
Scientific paper
Oct 1997
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997geoji.131....1t&link_type=abstract
Geophysical Journal International, Vol. 131, No. 1, p. 1 - 8
Mathematics
Logic
29
Geoid: Geodynamics, Geoid: Models, Earth Mantle: Viscosity
Scientific paper
The authors address several of the most straightforward problems inherent in geoid modelling, namely the issues of viscosity structure resolution, uncertainties in appropriate boundary conditions, and differences among mantle heterogeneity models. A robust feature of all models is a lower-mantle viscosity at least a factor of 30 greater than that of the upper mantle, but there is little resolution with regard to finer details such as lithospheric or uppermost mantle ("low-viscosity zone") viscosity. Ironically, free-slip boundary conditions result in the best fits to the geoid in all cases, but all boundary conditions exhibit predictable trade-offs with the uppermost-mantle viscosity. Models with a single viscosity layer representing the lower mantle yield similar dynamic topography estimates of the order of 700-1000 m in amplitude, regardless of the finer details of upper-mantle viscosity structure, boundary conditions or input heterogeneity models. Comparing mantle heterogeneity models based on two independent seismological determinations (Harvard and Berkeley models) and on the history of subduction, the authors find that these models are virtually indistinguishable regarding inferences of mantle viscosity structure and amplitude of dynamic topography, and in terms of the effects of different boundary conditions. Uncertainties concerning which type of boundary condition is appropriate are much more important than which mantle heterogeneity model is chosen. Given other uncertainties in modelling the geoid, particularly the strong effects due to lateral viscosity variations for intermediate (<10,000 km) wavelengths, the authors conclude that the class of dynamic geoid models explored so far cannot reliably elucidate the details of upper-mantle viscosity structure.
Richards Anita M.
Thoraval Catherine
No associations
LandOfFree
The geoid constraint in global geodynamics: viscosity structure, mantle heterogeneity models and boundary conditions. does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The geoid constraint in global geodynamics: viscosity structure, mantle heterogeneity models and boundary conditions., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The geoid constraint in global geodynamics: viscosity structure, mantle heterogeneity models and boundary conditions. will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1770840