HR: 0800h
AN: G51A-0141    [Abstracts]
TI: On the Combined Use of GRACE and Geodetic Observations for Vertical Motion in the Great Lakes Region
AU: Rangelova, E
EM: evrangel@ucalgary.ca
AF: Department of Geomatics Engineering, Schulich School of Engineering, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada
AU: Fotopoulos, G
EM: georgia.fotopoulos@utoronto.ca
AF: Department of Civil Engineering, University of Toronto, 35 St. George Street, Toronto, ON M5S 1A4, Canada
AU: * Sideris, M G
EM: sideris@ucalgary.ca
AF: Department of Geomatics Engineering, Schulich School of Engineering, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada
AB: As the measurements from geodetic observations become more accurate, they are implemented to not only empirically derive velocity surfaces but also to infer mantle viscosity. Accurate empirical models for vertical crustal motion are of particular interest in the Great Lakes region, where the line of zero motion (hinge line) is an important constraint for postglacial rebound modelling. With the abundance of geodetic observations in this region, the gradient of the velocity surface can be described relatively well. However, the hinge line can deviate from one data set to another due to datum inconsistencies, different time span and accuracy of measurements, different spatial resolution and presence of erroneous data, as well as the underlying mathematical model. Reliably estimated error bounds of the empirical rates of crustal displacement are required to define the uncertainty with which the mantle viscosity profile can be inferred in the inversion of the empirical rates. In this study, we combine the most recent GRACE-observed rates of gravity change converted to vertical crustal motion, water gauge (and altimetry) data, and GPS velocity data. The combined vertical motion model is realized via a least-squares adjustment procedure, which incorporates variance-component estimation and robust outlier detection. The latter is necessary to ensure reliable estimates of relative errors in the combined least-squares adjustment (via re-scaling of covariance matrices) and to ensure that the final vertical motion model is not distorted by erroneous data. The combined vertical motion model shows a subsidence of -2 mm/yr along the southern shores and uplift of 3 – 4 mm/yr along the northern shores.
DE: 1217 Time variable gravity (7223, 7230)
DE: 1295 Integrations of techniques
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
SC: Geodesy [G]
MN: 2007 Fall Meeting