HR: 0830h
AN: S31E-0812    [PDF]
TI: Surface Wave Studies of the Greenland Shield
AU: Larsen, T B
EM: tbl@kms.dk
AF: National Survey and Cadastre, Rentemestervej 8, Copenhagen NV, DK-2400 Denmark
AU: * Darbyshire, F A
EM: fiona@seismo.nrcan.gc.ca
AF: Geological Survey of Canada, 7 Observatory Crescent, Ottawa, ON K1A 0Y3 Canada
AU: Mosegaard, K
EM: klaus@gfy.ku.dk
AF: University of Copenhagen, Juliane Maries Vej 30, Copenhagen {\O}, DK-2100 Denmark
AU: Dahl-Jensen, T
EM: tdj@geus.dk
AF: Geological Survey of Denmark and Greenland, {\O}ster Voldgade 10, Copenhagen K, DK-1350
AU: Gudmundsson, {
EM: og@dlc.ku.dk
AF: Danish Lithosphere Centre, {\O}ster Voldgade 10, L, Copenhagen K, DK-1350 Denmark
AU: Bach, T
EM: torben.bach@geo.au.dk
AF: University of Aarhus, Nordre Ringgade 1, Aarhus C, DK-8000 Denmark
AU: Gregersen, S
EM: srg@kms.dk
AF: National Survey and Cadastre, Rentemestervej 8, Copenhagen NV, DK-2400 Denmark
AU: Pedersen, H
EM: helle.pedersen@obs.ujf-grenoble.fr
AF: Universit{\'e} Joseph Fourier, BP 53, Grenoble, Cedex 9, 38041 France
AU: Hanka, W
EM: hanka@gfz-potsdam.de
AF: Geoforschungszentrum Potsdam, Telegrafenberg, Potsdam, D-14473 Germany
AB: We investigate the lithospheric structure beneath Greenland using Rayleigh waves recorded by 21 broadband seismograph stations deployed across Greenland. This study forms part of the ongoing 'GLATIS' (Greenland Lithosphere Analysed Teleseismically on the Ice Sheet) project. Phase velocity curves are generated for paths between pairs of seismograph stations, using the two-station method of Gomberg et al. (1988). Dispersion curves for 45 paths have been obtained, for the period range 25-160 seconds. The results from the dispersion curves are combined to produce phase velocity maps for several Rayleigh wave periods, assuming isotropic conditions. Each map shows robust lateral structural variations across Greenland. At intermediate periods, we see a significant high-velocity anomaly in the southwest, and a low-velocity anomaly in the east is seen at intermediate and long periods. The results of the phase velocity inversion are used to construct localised dispersion curves for two parallel north-south profiles in southern Greenland. These curves are then inverted for shear-wave velocity structure. The results show a high-velocity 'lid' structure, which we interpret as the seismological lithosphere. The 'lid' overlies a zone of relatively low velocity, beneath which the shear wave velocity increases gradually with depth. A large data set of local and regional earthquakes is used to generate several hundred group velocity curves for the Greenland / western North Atlantic region. The individual dispersion curves are combined to produce a set of detailed group velocity maps for the region. The study provides us with important new information about the structure and properties of the lithosphere and upper mantle beneath Greenland and the surrounding region.
DE: 0905 Continental structures (8109, 8110)
DE: 7218 Lithosphere and upper mantle
DE: 7255 Surface waves and free oscillations
DE: 9315 Arctic region
SC: Seismology [S]
MN: 2003 Fall Meeting