Observation of glacial isostatic adjustment in "stable" North America with GPS

Giovanni F. Sella*, Seth Stein, Timothy H. Dixon, Michael Craymer, Thomas S. James, Stephane Mazzotti, Roy K. Dokka

*Corresponding author for this work

Research output: Contribution to journalArticle

259 Scopus citations

Abstract

Motions of three hundred and sixty Global Positioning System (GPS) sites in Canada and the United States yield a detailed image of the vertical and horizontal velocity fields within the nominally stable interior of the North American plate. By far the strongest signal is the effect of glacial isostatic adjustment (GIA) due to ice mass unloading during deglaciation. Vertical velocities show present-day uplift (∼10 mm/yr) near Hudson Bay, the site of thickest ice at the last glacial maximum. The uplift rates generally decrease with distance from Hudson Bay and change to subsidence (1-2 mm/yr) south of the Great Lakes. The "hinge line" separating uplift from subsidence is consistent with data from water level gauges along the Great Lakes, showing uplift along the northern shores and subsidence along the southern ones. Horizontal motions show outward motion from Hudson Bay with complex local variations especially in the far field. Although the vertical motions are generally consistent with the predictions of GIA models, the horizontal data illustrate the need and opportunity to improve the models via more accurate descriptions of the ice load and laterally variable mantle viscosity.

Original languageEnglish (US)
Article numberL02306
JournalGeophysical Research Letters
Volume34
Issue number2
DOIs
StatePublished - Jan 28 2007

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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    Sella, G. F., Stein, S., Dixon, T. H., Craymer, M., James, T. S., Mazzotti, S., & Dokka, R. K. (2007). Observation of glacial isostatic adjustment in "stable" North America with GPS. Geophysical Research Letters, 34(2), [L02306]. https://doi.org/10.1029/2006GL027081