Geodetic constraints on glacial isostatic adjustment in Europe

Direct measurements of surface deformation due to Glacial Isostatic Adjustment (GIA) in Europe have been so far mostly limited to the present-day uplift area. Here, we use permanent GPS networks results to investigate the significance of GIA effects in Europe south of Fennoscandia. We show that uplift in Fennoscandia is surrounded by subsidence reaching as far south as the Alps, with a maximum vertical rate of 1.5 mm/yr between 50.5 - 53 degrees N. Horizontal velocity gradients show shortening between Fennoscandia and north-central Europe with strain rates of similar to 10(-9) yr(-1) and principal compressional strain axis pointing to the Gulf of Bothnia in a radial pattern. We find a very good quantitative agreement with the 3D surface displacement predicted by Milne et al. ( 2001), although the increase of misfit in far-field of Fennoscandia suggests that geodetic data outside of the uplift area may bring additional constraints to the rheological parameters used in GIA models.