Deep Continental Roots: The Effects of Lateral Variations of Viscosity on Post-Glacial Rebound
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The existence of lateral viscosity variations in the earth mantle could be inferred by recent tomographic results. This can potentially cause substantial changes in the interpretation of the results from usual postglacial uplift modelling which assumes a uniform mantle. In this work we study the impact of a high viscosity craton located below the lithosphere in Fennoscandia. The solution is obtained using a finite element code which treats the surface rebound of an axisymmetrical viscoelastic half-space. The effects on the vertical displacements and velocity fields could be of the order of 30% in the centre of deglaciated areas and become larger for horizontal displacements, strain-fields and vertical velocities at the peripheral region. Viscosity increases beneath continental regions with respect to oceanic regions may be able to explain the systematically lower viscosity values inferred from sea-level data from Pacific Island sites. Our findings are potentially very important in the interpretation of GPS data.
KeywordsGravity Anomaly Horizontal Displacement Maximum Shear Stress Global Position System Data Uniform Model
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