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<0.5 mm. The observed annual variations, however, disagree; this difference may be caused by some combination of local precipitation-induced site motion, unmodeled loading from other nearby sources, errors in the GSL model, and atmospheric errors." />



GEOPHYSICAL RESEARCH LETTERS, VOL. 30, NO. 3, 1111, doi:10.1029/2002GL016579, 2003



Crustal loading near Great Salt Lake, Utah



P. Elósegui and J. L. Davis



Harvard-Smithsonian Center for Astrophysics,

Cambridge, Massachusetts, USA



J. X. Mitrovica



Department of Physics, University of Toronto,

Toronto, Canada



R. A. Bennett



Harvard-Smithsonian Center for Astrophysics,

Cambridge, Massachusetts, USA



B. P. Wernicke



Division of Geological and Planetary Sciences, California Institute of Technology,

Pasadena, California, USA



Abstract



[1]   Two sites of the BARGEN GPS network are located ~30 km south of Great Salt Lake (GSL). Lake-level records since mid-1996 indicate seasonal water elevation variations of ~0.3 m amplitude superimposed on a roughly “decadal” feature of amplitude ~0.6 m. Using an elastic Green's function and a simplified load geometry for GSL, we calculate that these variations translate into radial crustal loading signals of ±0.5 mm (seasonal) and ±1 mm (decadal). The horizontal loading signals are a factor of ~2 smaller. Despite the small size of the expected loading signals, we conclude that we can observe them using GPS time series for the coordinates of these two sites. The observed amplitudes of the variations agree with the predicted decadal variations to <0.5 mm. The observed annual variations, however, disagree; this difference may be caused by some combination of local precipitation-induced site motion, unmodeled loading from other nearby sources, errors in the GSL model, and atmospheric errors.



Received 7 November 2002; revised 4 December 2002; accepted 23 December 2002; published 5 February 2003.



Index Terms: 1208 Geodesy and Gravity: Crustal movements—intraplate (8110); 1243 Geodesy and Gravity: Space geodetic surveys; 1299 Geodesy and Gravity: General or miscellaneous; 8164 Tectonophysics: Evolution of the Earth: Stresses—crust and lithosphere.