HR: 09:10h
AN: G31D-05    [Abstracts]
TI: Constraints on Glacial Isostatic Adjustment in Europe and Tectonics in the Western Mediterranean from Permanent GPS array solutions
AU: * Nocquet, J
EM: nocquet@ensg.ign.fr
AF: COMET, University of Oxford, Department of Earth Sciences, Parks Road, Oxford, 0X1 3PR United Kingdom
AU: * Nocquet, J
EM: nocquet@ensg.ign.fr
AF: LAREG/IGN, 6-8, avenue Blaise Pascal, Champ sur Marne, 77455 France
AU: * Nocquet, J
EM: nocquet@ensg.ign.fr
AF: CNRS - G‚osciences Azur, 250, rue Albert Einstein, Valbonne, 06560 France
AU: Calais, E
EM: ecalais@purdue.edu
AF: Department of Earth and Atmospheric Sciences, University of Purdue, 550 Stadium Mall Drive, West Lafayette, IN 47907-1 United States
AU: Parsons, B
EM: barry.parsons@earth.ox.ac.uk
AF: COMET, University of Oxford, Department of Earth Sciences, Parks Road, Oxford, 0X1 3PR United Kingdom
AB: We present a new velocity field for Europe and the Mediterranean spanning 8 years of data between 1996.0-2004.7 period, derived from a rigorous combination of (1) a selection of sites from the ITRF2000 solution, (2) a subset of sites from the European Permanent GPS Network solution, (3) a solution of the French national geodetic permanent GPS network (RGP), and (4) a solution of a permanent GPS network in the western Alps (REGAL). The resulting velocity field describes horizontal crustal motion at $\sim$150 sites with an accuracy of the order of 1 mm/yr or better. We first investigate the Glacial Isostatic Adjustment deformation in Europe south of Fennoscandia. Uplift in Fennoscandia is surrounded by a subsidence trough reaching as far south as the Alps, with a maximum subsiding rate of 1.5~mm/yr located at latitude 50.5-53$^\circ$N. The vertical GPS velocities agree with the model prediction of Milne et al. (2001) at 0.7 mm/yr (wrms). Looking at the horizontal velocities, shortening occurs between Fennoscandia and northern central Europe with magnitude of strain rate of the order 10$^{-9}$ $yr^{-1}$. The principal direction of shortening changes longitudinally and systematically points toward the Gulf of Botnia. No deformation can be detected south of latitude 52$^\circ$N. In particular, A stability analysis shows that no motion can be resolved across the Rhine Graben as well as across the Pyrenees and the islands of western Mediterranean. As a consequence, the totality of the shortening must be accommodated in Northern Africa and in the Betics in Spain. In Italy, although a counter-clockwise rotation of the Adriatic plate explains the general pattern of velocities, detailed study indicates internal deformation of the microplate and NE-SW extensional strain rates as high as 40 ń 10 .10$^{-9}$ yr$^{-1}$ occurs in the Apennines. Finally, we find that the Dinarides accommodates $\sim$3.5 mm/yr of NE-SW shortening between Dubrovnik and Sarajevo.
DE: 8110 Continental tectonics--general (0905)
DE: 1206 Crustal movements--interplate (8155)
DE: 1208 Crustal movements--intraplate (8110)
DE: 1229 Reference systems
DE: 1236 Rheology of the lithosphere and mantle (8160)
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting