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TitleSinking of the upper midwest, rise of the Great Lakes, and collapse of the Laurentide Ice Sheet forebulge
AuthorArgus, D F; Ratliff, B; DeMets, C; Borsa, A, a; Wiese, D N; Kreemer, C; Lau, N; Lyman Kilb, D; Mumma, S; Crowley, J WORCID logo
SourceAmerican Geophysical Union Fall Meeting 2019, abstracts; G53A-02, 2019 p. 1 Open Access logo Open Access
LinksOnline - En ligne
Alt SeriesNatural Resources Canada, Contribution Series 20190253
PublisherAmerican Geophysical Union
MeetingAmerican Geophysical Union Fall Meeting 2019; San Francisco, CA; US; December 9-13, 2019
DocumentWeb site
Mediaon-line; digital
File formathtml; pdf
ProvinceOntario; Quebec; Manitoba
NTS30; 31; 32; 40; 41; 42; 52; 62
AreaGreat Lakes; Michigan; Wisconsin; Canada; United States of America
Lat/Long WENS-100.0000 -74.0000 51.0000 35.0000
Subjectstectonics; geophysics; hydrogeology; Nature and Environment; Science and Technology; glacial history; deglaciation; tectonic history; isostasy; isostatic rebound; isostatic compensation; crustal movements; crustal uplift; subsidence; crustal models; displacement; surface waters; lakes; viscosity; hydrologic environment; geodesy; water loading; Laurentide Ice Sheet; Gravity Recovery and Climate Experiment (GRACE); Global positioning systems; Phanerozoic; Cenozoic; Quaternary
Illustrationsgeoscientific sketch maps
ProgramCanadian Geodetic Survey Geodetic Analysis and Development - Gravity and heights systems
Released2019 12 01
AbstractThe Great Lakes rose sharply by 0.6-1 m from 2013 to 2016, increasing surface water volume by 220 km3. Solid Earth's elastic response to the increased mass load is approximately known: the seafloor beneath the Great Lakes fell 8-18 mm, and the adjacent land fell 3-12 mm and moved horizontally inward toward the Great Lakes 0-2 mm. Correcting GPS site positions for Great Lakes loading straightens the evolution of position as a function of time, making the time series more nearly a straight line reflecting a constant velocity. Michigan, Wisconsin, and southern Ontario have sunk at 1-4 mm/yr over the past 12 years. We find this subsidence to be caused secondarily by solid Earth's elastic response to Great Lakes water increase and primarily by viscous collapse of the forebulge of the Laurentide ice sheet (in model ICE6G/VM5a). We use residual GPS vertical displacements to infer changes in total water storage at Earth's surface. We find seasonal water volume in the Great Lakes is maximum around August, 5 months after the maximum volume of total water on land in March. We furthermore deduce from GPS and GRACE that seasonal changes in total water are understated by a factor of 2 in hydrology models. An inference of this study is that vertical rates of motion of Earth's surface estimated using GPS should be corrected for Great Lakes loading before they are used to constrain models of postglacial rebound. This study provides the set up to integrate GPS and GRACE to more accurately infer change in total water storage across the United States. After explicitly removing change in Great Lakes water, we combine GRACE and GPS to infer changes in total water reflecting the total of all water cycle processes: precipitation, river runoff, evaporation, groundwater change, the seeping of rain water and melting snow into the ground, and being parched from the ground.

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