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TitleGPS coordinate time series measurements in Ontario and Quebec, Canada
AuthorAlinia, H S; Tiampo, K F; James, T S
SourceJournal of Geodesy 2017 p. 1-31,
Alt SeriesEarth Sciences Sector, Contribution Series 20160263
Mediaon-line; digital
File formatpdf
ProvinceNunavut; Ontario; Quebec
NTS30; 40; 41; 31; 20; 21; 22; 32; 42; 43; 33; 23; 44; 34; 24; 45; 35; 25; 26; 36; 46
AreaSouthern Ontario Seismic Zone; Western Quebec Seismic Zone; Charlevoix Seismic Zone; Lower St. Lawrence Seismic Zone; Boothia Ungava Zone
Lat/Long WENS -88.0000 -72.0000 66.0000 42.0000
Subjectsisostatic rebound; models; GPS position time series; Bernese GPS processing; Reference frame
Illustrationslocation maps; tables; graphs; plots
ProgramWestern Canada Geohazards Project, Public Safety Geoscience
Released2017 01 16
AbstractNew precise network solutions for continuous GPS (cGPS) stations distributed in eastern Ontario and western Québec provide constraints on the regional three dimensional crustal velocity field. Five years of continuous observations at fourteen cGPS sites were analyzed using Bernese GPS processing software. Several different sub-networks were chosen from these stations and the data processed and compared to in order to select the optimal configuration to accurately estimate the vertical and horizontal station velocities and minimize the associated errors. The coordinate time series were then compared to the crustal motions from global solutions and the optimized solution is presented here. A noise analysis model with power law and white noise, which best describes the noise characteristics of all three components, was employed for the GPS time series analysis. The linear trend, associated uncertainties, and the spectral index of the power law noise were calculated using a Maximum Likelihood Estimation (MLE) approach. The residual horizontal velocities, after removal of rigid plate motion, have a magnitude consistent with expected glacial isostatic adjustment (GIA). The vertical velocities increase from subsidence of almost 1.9 mm/year south of the Great Lakes to uplift near Hudson Bay, where the highest rate is approximately 10.9 mm/year. The residual horizontal velocities range from approximately 0.5 mm/year, oriented south-southeastwards, at the Great Lakes to nearly 1.5 mm/year directed toward the interior of Hudson Bay at stations adjacent to its shoreline. Here, the velocity uncertainties are estimated at less than 0.6 mm/year for the horizontal component and 1.1 mm/year for the vertical component. A comparison between the observed velocities and GIA model predictions, for a limited range of Earth models, shows a better fit to the observations for the Earth model with the smallest upper mantle viscosity and the largest lower mantle viscosity. However, the pattern of horizontal deformation is not well explained in the north, along Hudson Bay, suggesting that revisions to the ice thickness history are needed to improve the fit to observations.
Summary(Plain Language Summary, not published)
The paper describes the collection and analysis of Global Positioning System (GPS) measurements made at bedrock sites in Ontario and Quebec, the determination of crustal motions from the measurements, and the interpretation of the crustal motion in terms of glacial isostatic adjustment (GIA). GIA is the ongoing response of the solid Earth to the unloading of the surface of the Earth that occurred thousands of years ago when the ice sheet that covered most of Canada shrank and disappeared. The crustal motion measurements are largely consistent with the model predictions, except in northern Quebec where revisions to the GIA model may be needed.