HR: 0800h
AN: G31B-0797    [Abstracts]
TI: Crustal Deformation Velocities From Episodic Regional Measurements at Canadian Base Network Sites
AU: * Henton, J A
EM: jhenton@nrcan.gc.ca
AF: Natural Resources Canada, Geodetic Survey Division (Canada Centre for Remote Sensing) 615 Booth Street, Ottawa, ON K1A 0E9 Canada
AU: Craymer, M R
EM: craymer@nrcan.gc.ca
AF: Natural Resources Canada, Geodetic Survey Division (Canada Centre for Remote Sensing) 615 Booth Street, Ottawa, ON K1A 0E9 Canada
AU: Piraszewski, M
EM: Mike.Piraszewski@nrcan-rncan.gc.ca
AF: Natural Resources Canada, Geodetic Survey Division (Canada Centre for Remote Sensing) 615 Booth Street, Ottawa, ON K1A 0E9 Canada
AU: Lapelle, E
EM: Earl.Lapelle@nrcan-rncan.gc.ca
AF: Natural Resources Canada, Geodetic Survey Division (Canada Centre for Remote Sensing) 615 Booth Street, Ottawa, ON K1A 0E9 Canada
AB: Initiated in 1994, the Canadian Base Network (CBN) is a network of pillar monuments with forced-centering mounts for Global Positioning System (GPS) receiver antennae. Accurately positioned three-dimensionally with GPS, the CBN can serve as a monitoring network for deformation studies of the Canadian landmass. By combining nearly ten years of repeated multi-epoch (episodic) GPS measurements, we estimate velocities at the CBN sites to provide an increased spatial sampling of crustal deformation throughout Canada. To determine individual station velocities, we systematically combine regional CBN solutions for each measurement epoch into a single Canada-wide, multi-epoch cumulative solution. In order to generate time series of consistent, high-accuracy coordinates for velocity estimation, it is necessary to ensure consistency in the realization of the reference frame. We accomplish this by aligning each of the individual CBN solutions to the IGS realization of ITRF using a subset of stations from a recent IGS cumulative solution for the IGS global network. Fortunately, there are many IGS stations in Canada and most were included in each regional CBN solution to strengthen the realization of the reference frame and ensure consistency between epochs. We also ensure consistent and realistic weighting of the individual CBN solutions though the estimation of variance components relative to the IGS global solution. After the individual CBN solutions are aligned and weighted, they are combined together in a simultaneous cumulative solution for velocities at each site. Preliminary results from the analysis of CBN time series in eastern Canada exhibit a spatially coherent pattern of uplift consistent with the expected post-glacial rebound (PGR) signal. For this region the highest observed uplift rates are in the vicinity of James Bay through to southwestern Labrador; the rates then decrease to the south and towards the coastal Atlantic margins. Indeed, the Nouveau Quebec-Labrador region was the site of one of the major ice domes of the Laurentide Ice Sheet and the surrounding region is predicted to experiencing contemporary postglacial rebound. We compare these preliminary site-by-site results with those from our simultaneous cumulative solution, as well as those predicted by PGR models. In order to densify the velocity field in the Arctic and Great Lakes regions, future investigations will include additional, recent continuous and episodic GPS measurements in these areas of interest as well as continuous GPS measurements at selected CORS sites in the northern U.S. states.
DE: 8110 Continental tectonics--general (0905)
DE: 1208 Crustal movements--intraplate (8110)
DE: 1229 Reference systems
DE: 1243 Space geodetic surveys
DE: 1299 General or miscellaneous
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting