Fennoscandian strain rates from BIFROST GPS: A gravitating, thick-plate approach

• Published in: Journal of Geodynamics
• Language: English
• Published: Elsevier 2011
• Subjects: Space Geodesy; Recent Crustal Motions; Glacial Isostatic Adjustment; Canada; Curl; Chalmers; Fennoscandian; Lapland
• Online Access: http://hdl.handle.net/2262/60280; https://doi.org/10.1016/j.jog.2009.11.005

Abstract The aim of this investigation is to develop a method for the analysis of crustal strain determined by station networks that continuously collect measurements of Global Navigation Satellite Systems (GNSS). The major new ingredient is that we require a simultaneous minimum of the observation error and the elastic and potential energy of a thick elastic and gravitating slab. From this outset the method pursues a general approach not limited to the origin of the deforming process nor to assumptions of lateral homogeniety of the elastic and density structure. One present limitation, however, is the assumption of vertical uniformity in elasticity, which is relevant in the flexure mode. The observations that we analyse come from eight years worth of daily solutions from continuous BIFROST GPS measurements in the permanent networks of the Nordic countries and their neighbours. Reducing the observed three-dimensional velocities with best-fitting predictions for the effects of glacial isostatic adjustment (GIA) we find strain rates of typically 4?6 nano/yr in the interior of the rebound area, shear strain being slightly more pronounced compared to areal strain. The largest strain rates, 12 nano/yr, accompanied by a curl feature of 4 nrad/yr, are found in the Finnmarken area where, however, the GNSS network density is much lower than in the central and southern parts. The somewhat poor network geometry is found to create spurious curl at 1 to 2 nrad/yr in the Lapland-Finnmarken area. We also find that the strain generated by flexure due to GIA is important. In th emodel, the extensional regime seen at the surface turns over into a compressive style already at moderate depth, some 50km. correspondance: Corresponding author. (Scherneck, H.-G.) [e-mail] (Scherneck, H.-G.) Chalmers University of Technology--> , Department of Radio and Space Science--> , SE-412 96 Goteborg--> - SWEDEN (Scherneck, H.-G.) Chalmers University of Technology--> , Department of Radio and Space Science--> , SE-412 96 Goteborg--> - SWEDEN (Scherneck, H.-G.) National Land Survey of Sweden--> , SE-801 82 Gavle--> - SWEDEN (Lidberg, M.) Chalmers University of Technology--> , Department of Radio and Space Science--> , SE-412 96 Goteborg--> - SWEDEN (Haas, R.) Chalmers University of Technology--> , Department of Radio and Space Science--> , SE-412 96 Goteborg--> - SWEDEN (Johansson, Jan M.) University of Ottawa--> , Department of Geodsciences--> , Ottawa--> , Ont.--> - CANADA (Milne, G.A.) CANADA SWEDEN Received: 2008-11-22 Revised: 2009-09-25 Accepted: 2009-11-16