Constraints on mantle viscosity from relative sea level variations in Hudson Bay

• Main Authors: Mitrovica, J. X., Peltier, W. R.
• Format: Other/Unknown Material
• Language: unknown
• Published: 1992
• Subjects: 46; Hudson; Hudson Bay
• Online Access: http://ntrs.nasa.gov/search.jsp?R=19920064802

Frechet kernels for the RSL data in Hunson Bay are computed to determine the detailed depth-dependent sensitivity of the data to variations in a viscosity profile which is consistent with the past inferences. The RSL data provide a robust constraint on the average viscosity in the top half of the lower mantle only (the average must be near 10 exp 21 Pa s). The data admit models whose average viscosity in the deep mantle (below 1800 km depth) and in the upper mantle can differ significantly from the value (near 10 exp 21 Pa s) estimated for the top half of the lower mantle. The total variation in the viscosity from the surface to the CMB can exceed an order of magnitude or more and still satisfy the constraint provided by the Hudson Bay RSL data set. The necessity of invoking an isoviscous mantle model in previous studies is a consequence of the limited class of viscosity model solutions employed in those studies.