| Titre | Sinking of the upper midwest, rise of the Great Lakes, and collapse of the Laurentide Ice Sheet forebulge |
| Auteur | Argus, D F; Ratliff, B; DeMets, C; Borsa, A, a; Wiese, D N; Kreemer, C; Lau, N; Lyman Kilb, D; Mumma, S; Crowley, J W |
| Source | American Geophysical Union Fall Meeting 2019, abstracts; G53A-02, 2019 p. 1 (Accès ouvert) |
| Liens | Online - En ligne
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| Année | 2019 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20190253 |
| Éditeur | American Geophysical Union |
| Réunion | American Geophysical Union Fall Meeting 2019; San Francisco, CA; US; décembre 9-13, 2019 |
| Document | site Web |
| Lang. | anglais |
| Media | en ligne; numérique |
| Formats | html; pdf |
| Province | Ontario; Québec; Manitoba |
| SNRC | 30; 31; 32; 40; 41; 42; 52; 62 |
| Lat/Long OENS | -100.0000 -74.0000 51.0000 35.0000 |
| Sujets | antecedents glaciaires; déglaciation; antécédents tectoniques; isostasie; relèvement isostatique; compensation isostatique; mouvements de la croûte; soulèvement de la croûte; affaissement; modèles de la
croûte; déplacement; eaux de surface; lacs; viscosité; milieu hydrologique; géodésie; chargement d'eau; Calotte glaciaire Laurentide; système de positionnement global; tectonique; géophysique; hydrogéologie; Nature et environnement; Sciences et
technologie; Phanérozoïque; Cénozoïque; Quaternaire |
| Illustrations | geoscientific sketch maps |
| Programme | Levés géodésiques du
Canada, Analyse et développement géodésiques - Gravimétrie et systèmes altimétriques |
| Diffusé | 2019 12 01 |
| Résumé | (disponible en anglais seulement)
The 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. |
| GEOSCAN ID | 321477 |
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