Viscoelastic relaxation of a Burgers half-space: implications for the interpretation of the Fennoscandian uplift

• Published in: Geophysical Journal International
• Main Authors: Rümpker, Georg, Wolff, Detlef
• Format: Text
• Language: English
• Published: Oxford University Press 1996
• Subjects: Treitel Section; Fennoscandia; Fennoscandian; Ice Sheet
• Online Access: http://gji.oxfordjournals.org/cgi/content/short/124/2/541; https://doi.org/10.1111/j.1365-246X.1996.tb07036.x

We investigate the load-induced response of a Burgers earth model. In particular, using the incremental field equations and interface conditions of viscoelastodynamics, we give closed-form solutions for a two-layer half-space subjected to surface loading. In the special case of homogeneity, the solution shows that the Burgers half-space is characterized by two fundamental normal modes: M o and M ∞ . They correspond to the short-and long-time viscosities, η o and η ∞ , which describe the creep behaviour of the transient Burgers rheology at short and long times after the onset of loading. In the more general case of a Burgers substratum overlain by an elastic layer, the number of normal modes increases to four: M o , L o , M ∞ , L ∞ . Values of the parameters specifying the Burgers substratum are estimated by predicting the observed post-glacial uplift in Fennoscandia with a simple model of the Pleistocene glaciation history. The calculations return the following results: (1) an upper bound on η ∞ cannot be determined; (2) a comparison with uplift curves for a steady-state Maxwell substratum shows that the marginal and peripheral regions of the Fennoscandian ice sheet are most sensitive to transient creep in the Earth's mantle; and (3) an estimate of η ∞ cannot be obtained without a priori knowledge of the other parameters of Burgers rheology.