HR: 0800h
AN: G21B-0497    [Abstracts]
TI: Uncertainty in the Motion of the North American Plate and its Impact
AU: * Freymueller, J T
EM: jeff.freymueller@gi.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK 99775, United States
AU: Elliott, J
EM: juliie@giseis.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK 99775, United States
AB: The motion of the North American plate in a geodetic reference frame is difficult to describe, because of the broad region of distributed tectonic activity in the west and the broad area of glacial-isostatic adjustment (GIA) in the north. Despite the large number of GPS sites in North America, the limited geographic extent of unambiguously stable North America increases the uncertainty in the estimate of the plate's angular velocity and makes the estimate sensitive to biases caused by even small systematic errors. Most estimates of the North American plate's angular velocity have not considered the effects of systematic biases, which is one reason why competing estimates often lie outside of the 95% confidence regions of each other. Additional uncertainty in the motion of the stable plate (in a geodetic frame such as ITRF) results from uncertainties in the realization of the frame itself, especially in the motion of the geocenter. The most recent estimates of the angular velocity come from Sella et al. (2007) and from the SNARF v.1 estimate. In the southeastern United States, these two angular velocities predict velocities that differ by only 0.1-0.3 mm/yr, so distinguishing between them using data from that region is exceptionally difficult. In the tectonically active western US, the difference between the two reaches 0.5 mm/yr, but in the far northwest, in Alaska and NE Russia, the difference can exceed 1 mm/yr. We estimate a more robust uncertainty for the motion of the plate in ITRF and test whether any sites in far northwestern North America can be considered to lie on the stable North American plate.
DE: 1209 Tectonic deformation (6924)
DE: 1211 Non-tectonic deformation
DE: 1229 Reference systems
DE: 1241 Satellite geodesy: technical issues (6994, 7969)
SC: Geodesy [G]
MN: 2007 Fall Meeting