Observations of postglacial uplift at Churchill, Manitoba

Churchill, Manitoba, is located near the centre of postglacial uplift caused by the Earth's recovery from the melting of the Laurentide Ice Sheet. The value of present-day uplift at Churchill has important implications in the study of postglacial uplift in that it can aid in constraining the thickness of the ice sheet and the rheology of the Earth. The tide-gauge record at Churchill since 1940 is examined, along with nearby Holocene relative sea-level data, geodetic measurements, and recent absolute gravimetry measurements, and a present-day rate of uplift of 8–9 mm/a is estimated. Glacial isostatic adjustment models yield similar estimates for the rate of uplift at Churchill. The effects of the tide-gauge record of the diversion of the Churchill River during the mid-1970's are discussed.

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3D glacial-isostatic adjustment models using geodynamically constrained Earth structures

10.5194/egusphere-egu21-13479 ◽

2021 ◽

Author(s):

Meike Bagge ◽

Volker Klemann ◽

Bernhard Steinberger ◽

Milena Latinović ◽

Maik Thomas

Keyword(s):

Solid Earth ◽

Sea Level ◽

Ice Sheet ◽

Sea Level Change ◽

Glacial Isostatic Adjustment ◽

Level Change ◽

Isostatic Adjustment ◽

Mantle Viscosity ◽

The Earth ◽

Earth Structures

<p>The interaction between ice sheets and the solid Earth plays an important role for ice-sheet stability and sea-level change and hence for global climate models. Glacial-isostatic adjustment (GIA) models enable simulation of the solid Earth response due to variations in ice-sheet and ocean loading and prediction of the relative sea-level change. Because the viscoelastic response of the solid Earth depends on both ice-sheet distribution and the Earth&#8217;s rheology, independent constraints for the Earth structure in GIA models are beneficial. Seismic tomography models facilitate insights into the Earth&#8217;s interior, revealing lateral variability of the mantle viscosity that allows studying its relevance in GIA modeling. Especially, in regions of low mantle viscosity, the predicted surface deformations generated with such 3D GIA models differ considerably from those generated by traditional GIA models with radially symmetric structures. But also, the conversion from seismic velocity variations to viscosity is affected by a set of uncertainties. Here, we apply geodynamically constrained 3D Earth structures. We analyze the impact of conversion parameters (reduction factor in Arrhenius law and radial viscosity profile) on relative sea-level predictions. Furthermore, we focus on exemplary low-viscosity regions like the Cascadian subduction zone and southern Patagonia, which coincide with significant ice-mass changes.</p>

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A glacial isostatic adjustment model for the central and northern Laurentide Ice Sheet based on relative sea level and GPS measurements

Geophysical Journal International ◽

10.1093/gji/ggw103 ◽

2016 ◽

Vol 205 (3) ◽

pp. 1618-1636 ◽

Cited By ~ 21

Author(s):

K.M. Simon ◽

T.S. James ◽

J.A. Henton ◽

A.S. Dyke

Keyword(s):

Sea Level ◽

Ice Sheet ◽

Laurentide Ice Sheet ◽

Glacial Isostatic Adjustment ◽

Gps Measurements ◽

Relative Sea Level ◽

Isostatic Adjustment ◽

Adjustment Model

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Comparing a thermo-mechanical Weichselian ice sheet reconstruction to GIA driven reconstructions: aspects of earth response and ice configuration

Solid Earth Discussions ◽

10.5194/sed-5-2345-2013 ◽

2013 ◽

Vol 5 (2) ◽

pp. 2345-2388 ◽

Cited By ~ 1

Author(s):

P. Schmidt ◽

B. Lund ◽

J-O. Näslund

Keyword(s):

Sea Level ◽

Ice Sheet ◽

Younger Dryas ◽

Slow Phase ◽

Glacial Isostatic Adjustment ◽

Relative Sea Level ◽

Isostatic Adjustment ◽

Earth Models ◽

Uplift Rates ◽

Best Fit

Abstract. In this study we compare a recent reconstruction of the Weichselian ice-sheet as simulated by the University of Main ice-sheet model (UMISM) to two reconstructions commonly used in glacial isostatic adjustment (GIA) modeling: ICE-5G and ANU (also known as RSES). The UMISM reconstruction is carried out on a regional scale based on thermo-mechanical modelling whereas ANU and ICE-5G are global models based on the sea-level equation. The Weichselian ice-sheet in the three models are compared directly in terms of ice volume, extent and thickness, as well as in terms of predicted glacial isostatic adjustment in Fennoscandia. The three reconstructions display significant differences. UMISM and ANU includes phases of pronounced advance and retreat prior to the last glacial maximum (LGM), whereas the thickness and areal extent of the ICE-5G ice-sheet is more or less constant up until LGM. The final retreat of the ice-sheet initiates at earliest time in ICE-5G and latest in UMISM, while ice free conditions are reached earliest in UMISM and latest in ICE-5G. The post-LGM deglaciation style also differs notably between the ice models. While the UMISM simulation includes two temporary halts in the deglaciation, the later during the Younger Dryas, ANU only includes a decreased deglaciation rate during Younger Dryas and ICE-5G retreats at a relatively constant pace after an initial slow phase. Moreover, ANU and ICE-5G melt relatively uniformly over the entire ice-sheet in contrast to UMISM which melts preferentially from the edges. We find that all three reconstructions fit the present day uplift rates over Fennoscandia and the observed relative sea-level curve along the Ångerman river equally well, albeit with different optimal earth model parameters. Given identical earth models, ICE-5G predicts the fastest present day uplift rates and ANU the slowest, ANU also prefers the thinnest lithosphere. Moreover, only for ANU can a unique best fit model be determined. For UMISM and ICE-5G there is a range of earth models that can reproduce the present day uplift rates equally well. This is understood from the higher present day uplift rates predicted by ICE-5G and UMISM, which results in a bifurcation in the best fit mantle viscosity. Comparison of the uplift histories predicted by the ice-sheets indicate that inclusion of relative sea-level data in the data fit can reduce the observed ambiguity. We study the areal distributions of present day residual surface velocities in Fennoscandia and show that all three reconstructions generally over-predict velocities in southwestern Fennoscandia and that there are large differences in the fit to the observational data in Finland and northernmost Sweden and Norway. These difference may provide input to further enhancements of the ice-sheet reconstructions.

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Relative sea-level data from the SEAMIS database compared to ICE-5G model predictions of glacial isostatic adjustment

Data in Brief ◽

10.1016/j.dib.2019.104600 ◽

2019 ◽

Vol 27 ◽

pp. 104600 ◽

Cited By ~ 2

Author(s):

Thomas Mann ◽

Maren Bender ◽

Thomas Lorscheid ◽

Paolo Stocchi ◽

Matteo Vacchi ◽

...

Keyword(s):

Sea Level ◽

Glacial Isostatic Adjustment ◽

Relative Sea Level ◽

Isostatic Adjustment ◽

Level Data ◽

Model Predictions

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A century of sea level data and the UK's 2013/14 storm surges: an assessment of extremes and clustering using the Newlyn tide gauge record

Ocean Science Discussions ◽

10.5194/osd-11-1995-2014 ◽

2014 ◽

Vol 11 (4) ◽

pp. 1995-2028 ◽

Cited By ~ 11

Author(s):

M. P. Wadey ◽

I. D. Haigh ◽

J. M. Brown

Keyword(s):

Sea Level ◽

Return Period ◽

Tide Gauge ◽

Storm Surges ◽

High Water ◽

Lower Probability ◽

Tide Gauge Record ◽

Storm Activity ◽

Sea Levels ◽

Level Data

Abstract. For the UK's longest and most complete sea level record (Newlyn), we assess extreme high water events and their temporal clustering; prompted by the 2013/2014 winter of flooding and storms. These are set into context against this almost 100 yr record. We define annual periods for which storm activity, tides and sea levels can be compared on a year-by-year basis. Amongst the storms and high tides which affected Newlyn the recent winter produced the largest recorded high water (3 February 2014) and five others above a 1 in 1 yr return period. The large magnitude of tide and mean sea level, and the close inter-event spacings (of large return period high waters), suggests that the 2013/2014 high water "season" may be considered the most extreme on record. However, storm and sea level events may be classified in different ways. For example in the context of sea level rise (which we calculate linearly as 1.81 ± 0.1 mm yr−1 from 1915 to 2014), a lower probability combination of surge and tide occurred on 29 January 1948, whilst 1995/1996 storm surge season saw the most high waters of ≥ 1 in 1 yr return period. We provide a basic categorisation of five types of high water cluster, ranging from consecutive tidal cycles to multiple years. The assessment is extended to other UK sites (with shorter sea level records and different tide-surge characteristics), which suggests 2013/2014 was extreme, although further work should assess clustering mechanisms and flood system "memory".

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Constraints on Glacial Isostatic Adjustment from GOCE and Sea Level Data

Pure and Applied Geophysics ◽

10.1007/s00024-004-0503-3 ◽

2009 ◽

Vol 166 (8-9) ◽

pp. 1261-1281 ◽

Cited By ~ 5

Author(s):

L. L. A. Vermeersen ◽

H. H. A. Schotman

Keyword(s):

Sea Level ◽

Glacial Isostatic Adjustment ◽

Isostatic Adjustment ◽

Level Data ◽

And Sea Level

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Glacial isostatic adjustment and the anomalous tide gauge record of eastern North America

Nature ◽

10.1038/379848a0 ◽

1996 ◽

Vol 379 (6568) ◽

pp. 848-848

Author(s):

James L. Davis ◽

Jerry X. Mitrovica

Keyword(s):

North America ◽

Tide Gauge ◽

Eastern North America ◽

Glacial Isostatic Adjustment ◽

Tide Gauge Record ◽

Isostatic Adjustment

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State-of-the-art in studies of glacial isostatic adjustment for the British Isles: a literature review

Earth and Environmental Science Transactions of the Royal Society of Edinburgh ◽

10.1017/s1755691016000074 ◽

2015 ◽

Vol 106 (3) ◽

pp. 145-170 ◽

Cited By ~ 3

Author(s):

Julia Stockamp ◽

Paul Bishop ◽

Zhenhong Li ◽

Elizabeth J Petrie ◽

Jim Hansom ◽

...

Keyword(s):

Literature Review ◽

Sea Level ◽

Glacial Isostatic Adjustment ◽

British Isles ◽

Data Types ◽

Geological Evidence ◽

Trend Surface ◽

Isostatic Adjustment ◽

Absolute Gravimetry ◽

Mantle Rheology

ABSTRACTUnderstanding the effects of glacial isostatic adjustment (GIA) of the British Isles is essential for the assessment of past and future sea-level trends. GIA has been extensively examined in the literature, employing different research methods and observational data types. Geological evidence from palaeo-shorelines and undisturbed sedimentary deposits has been used to reconstruct long-term relative sea-level change since the Last Glacial Maximum. This information derived from sea-level index points has been employed to inform empirical isobase models of the uplift in Scotland using trend surface and Gaussian trend surface analysis, as well as to calibrate more theory-driven GIA models that rely on Earth mantle rheology and ice sheet history. Furthermore, current short-term rates of GIA-induced crustal motion during the past few decades have been measured using different geodetic techniques, mainly continuous GPS (CGPS) and absolute gravimetry (AG). AG-measurements are generally employed to increase the accuracy of the CGPS estimates. Synthetic aperture radar interferometry (InSAR) looks promising as a relatively new technique to measure crustal uplift in the northern parts of Great Britain, where the GIA-induced vertical land deformation has its highest rate. This literature review provides an in-depth comparison and discussion of the development of these different research approaches.

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