HR: 0800h
AN: G21B-0501    [Abstracts]
TI: Mega-Network GPS Solutions: Producing a Consistent, Global-Scale, and High-Resolution View of Plate Tectonic Stability, Rotation, and Deformation.
AU: * Blewitt, G
EM: gblewitt@unr.edu
AF: Nevada Bureau of Mines and Geology, and Seismological Laboratory, University of Nevada, Reno, 1664 N. Virginia St., Reno, NV 89557-0178, United States
AU: Kreemer, C
EM: kreemer@unr.edu
AF: Nevada Bureau of Mines and Geology, and Seismological Laboratory, University of Nevada, Reno, 1664 N. Virginia St., Reno, NV 89557-0178, United States
AB: We present a single self-consistent GPS solution for over 2000 stations with ambiguity resolution applied for the period 1994--2007. Here we demonstrate that such `mega-network' GPS solutions provide a consistent, global- scale, and high-resolution view of plate tectonics in action. Specifically our solution is used to investigate the stability of the North American plate, its rotation, intra-plate deformation, and deformation in the Pacific-North America Plate boundary zone. A significant improvement in precision and accuracy attributable to ambiguity resolution is quantified by (1) the reduction of variance of station position time series (`repeatability'), (2) the reduction of variance in motions between stations within stable plate interiors, and (3) the relative smoothness of the velocity field in the Great Basin of western North America. The software developed to produce this solution, AMBIZAP Version 2.0 (ftp://gneiss.nbmg.unr.edu/ambizap) was made publicly available in August 2007. The method builds seamlessly on the precise point positioning (PPP) method invented by Zumberge et al. in 1997, additionally providing improved accuracy at a fraction of the original computational cost. Like PPP, the computation time of AMBIZAP (including network adjustment) is linear with number of stations N, unlike previous algorithms that exhibit power-law behavior, which presents a barrier to processing N >> 100. The longer-term significance of this development is the ease with which the software could be applied to N ~ 10000 GPS networks worldwide within the foreseeable future, including the N > 1000 Plate Boundary Observatory, which is already nearing completion.
DE: 1209 Tectonic deformation (6924)
DE: 1229 Reference systems
DE: 1294 Instruments and techniques
DE: 8103 Continental cratons
DE: 8158 Plate motions: present and recent (3040)
SC: Geodesy [G]
MN: 2007 Fall Meeting