HR: 1340h
AN: G33A-0017    [Abstracts]
TI: Ongoing Glacio-Isostatic Crustal Deformation Around Vatnajokull ice cap, Iceland due to Ice Retreat: Observations and Finite Element Modeling
AU: * Pagli, C
EM: carolina@hi.is
AF: Nordic Volcanological Center, Institute of Earth Sciences, University of Iceland, Sturlugata 7, Reykjavik, 101 Iceland
AU: Sigmundsson, F
EM: fs@hi.is
AF: Nordic Volcanological Center, Institute of Earth Sciences, University of Iceland, Sturlugata 7, Reykjavik, 101 Iceland
AU: Sturkell, E
EM: sturkell@hi.is
AF: Nordic Volcanological Center, Institute of Earth Sciences, University of Iceland, Sturlugata 7, Reykjavik, 101 Iceland
AU: Geirsson, H
EM: dori@vedur.is
AF: Icelandic Meteorological Office, Bustadavegur 9, Reykjavik, 150 Iceland
AU: Einarsson, P
EM: palli@raunvis.hi.is
AF: Institute of Earth Sciences, University of Iceland, Sturlugata 7, Reykjavik, 101 Iceland
AU: Lund, B
EM: Bjorn.Lund@geo.uu.se
AF: Department of Earth Sciences, Uppsala University, Villavagen 16, Uppsala, 752 36 Sweden
AU: Arnadottir, T
EM: thora1@hi.is
AF: Nordic Volcanological Center, Institute of Earth Sciences, University of Iceland, Sturlugata 7, Reykjavik, 101 Iceland
AB: Glacial rebound at the end of the Weichselian glaciation was completed in Iceland around 9000 years BP, but extensive ice volume retreat has occurred in Iceland in historical times. Since 1890 the Vatnajokull ice cap has lost about 300 km3 of ice. Unloading of the crust due to ice melting induces glacio-isostatic deformation around the ice cap. Ongoing uplift around the edges of Vatnajokull has been measured by lake leveling, continuous GPS and campaign GPS. GPS measurements around the south and east edges of Vatnajokull from 1996 to 2003 are consistent with vertical velocities between 23-16 mm/yr. The vertical velocities decay over a distance from 40 to 70 km from the center of the ice cap. Lake leveling measurements at Lake Langisjor at the SW edge of Vatnajokull from 1959 to 1991 show uplift rate of about 4 mm/yr between benchmarks spaced 15 km perpendicular to the ice edge. This uplift rate is consistent with GPS measurements. We use geodetic measurements of crustal deformation around Vatnajokull to constrain the rheological structure beneath Iceland. We have constructed an axisymmetric finite element model, using the software package ANSYS, to study the dynamic response of the Earth to a gradual ice load removal over the edges of the glacier. The model consists of an elastic plate overlying a Maxwell viscoelastic medium in an infinite half-space. The elastic plate corresponds to the uppermost crust that behaves in an elastic manner while the viscoelastic substrate corresponds to the lower crust and upper mantle. Preliminary results suggest a thickness of the elastic layer of about 10-20 km and a viscosity of about 1x1018 Pa s, while values lower than 1x1017 are unlikely. Higher uplift rates are expected in the future at the edges of the ice cap due to low viscosity under Iceland and increased ice thinning due to global warming.
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
SC: Geodesy [G]
MN: Fall Meeting 2005