hide
Free keywords:
Cryosphere; Gravity anomalies and Earth structure; geodesy and gravity; Satellite geodesy; tectonophysics
Abstract:
Viscoelastic deformations of an earth structure in response to a time-varying surface load are analyzed in
glacial isostatic adjustment (GIA). When solving this problem, aspects like flexure of the lithosphere and
retarded response of mantle material become evident. Quantified are these by flexural rigidity and relaxation
times. The concepts partly lose their relevance when changing from a 1D earth structure (only radial variations)
to a 2D or a 3D earth structure (lateral variations). In regions like Fennoscandia and Laurentide, which are
affected by GIA, lateral variations of the lithosphere and mantle structure are moderate and, so, the application
of a 1D earth structure is widely accepted. But, also for these two regions one has to keep in mind that the
respective 1D earth structures differ and that such an approximation mainly holds in the central part of the
respective region. In contrast, lateral variations or a local structure of different viscosity have to be considered
in areas like Patagonia, Antarctica or Alaska which is located above tectonic activity or covers a region with
significant lateral changes in earth structure. But, already for the two former examples one has to keep in mind
that the respective 1D earth structures inferred from GIA modelling differ between the two regions.
Focusing on the relaxation behavior and the mantle-material transport, we discuss the effect of lateral
variations on the deformation process. We will assess to which extent a 1D earth structure can
represent lateral variability in structural features, and, at which point a 3D earth structure has to be
considered. Such questions are of concern, when discussing GIA for geodetic applications as well as
in earth system modeling as this study contributes to the climate modeling initiative Palmod.
