Land uplift near Vatnajökull, Iceland, as observed by GPS in 1992, 1996 and 1999

Sjöberg, Lars E.; Pan, Ming; Erlingsson, Sigurður; Asenjo, Erick; Arnason, K.

doi:10.1111/j.1365-246x.2004.02353.x

Cited by 21 publications

(30 citation statements)

References 18 publications

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“…Although a detailed parameter space study was not carried out, our assumed viscosity (10 18 [37]). These results are compared with recent GPSbased up-lift rates [38]. Model 6, with a channel thickness of 50 km, gives a reasonable fit to the observations.…”

Section: Discussionmentioning

confidence: 70%

The lithosphere–asthenosphere boundary in the North-West Atlantic region

Kumar

Kind

Hanka

et al. 2005

Earth and Planetary Science Letters

138

107

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Section: Discussionmentioning

confidence: 70%

The lithosphere–asthenosphere boundary in the North-West Atlantic region

Kumar

Kind

Hanka

et al. 2005

Earth and Planetary Science Letters

138

107

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“…Table 1 summarizes the values inferred for lithosphere thickness and asthenosphere viscosity from interpretations of GIA. These values are the result of efforts to resolve the underlying structure of Iceland and Vatnajo¨kull, since the vertical-displacement rates are primarily dependent upon the asthenosphere viscosity, and the shape of the vertical-displacement rate curve crossing the center of the ice cap depends strongly upon the lithosphere thickness (e.g., SJO¨BERG et al, 2004). SIGMUNDSSON (1991) used sea-level observations from the period following the retreat of the late-Pleistocene ice sheet, assuming a 10 km-thick elastic lithosphere (the maximum depth to earthquakes in Southwest Iceland and to a lowresistivity layer found by magnetotellurics).…”

Section: Iceland's Underlying Viscosity Structurementioning

confidence: 99%

“…While asthenosphere viscosities lower than 1 Â 10 18 Pa s cannot be ruled out, we find the low values of ca. 10 17 Pa s discussed in the literature unnecessary (e.g., SJO¨BERG et al, 2004).…”

Section: Present-day Glacial-isostatic Response Around Vatnajo¨kullmentioning

confidence: 99%

Glacial-isostatic Adjustment and the Viscosity Structure Underlying the Vatnajökull Ice Cap, Iceland

Fleming

Martinec

Wolf

2007

Pure appl. geophys.

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We examine the dependence of glacial-isostatic adjustment (GIA) due to changes in the Vatnajo¨kull Ice Cap, Iceland, on the underlying viscosity structure. Iceland offers a unique case study for GIA research, with a thinner elastic lithosphere underlain by a low-viscosity zone or asthenosphere, as opposed to regions such as Fennoscandia or North America described by a thicker lithosphere, while not necessarily featuring an asthenosphere.A laterally homogeneous spherical earth model is used consisting of an elastic lithosphere, a viscoelastic asthenosphere, a viscoelastic upper and lower mantle and a fluid core. We examine the response of the earth model to three ice models with circular plans and cross-section profiles based on the assumption of perfectly plastic material, but with different load histories. These are: (1) A history where the ice cap grows from a AD 900 minimum to a maximum at 1890, followed by a uniform decrease until 1991, continuing to the present day at an average rate based on recent mass-balance measurements, (2) a history that is the same as the first, except for constant ice volumes prior to 1890, and (3) a history that is again the same as the first model, except that the post-1991 changes correspond to the measured mass-balance values. We first compare the response to each ice model using typical earth-model parameters for Iceland presented in the literature. We then undertake a parameter-space search, where we assess the importance of lithosphere thickness, asthenosphere viscosity and basal asthenosphere depth, to predicted vertical-displacement rates, and compare them to rates determined from GPS measurements obtained from campaigns conducted between 1991 and 1999.The earth-viscosity structure that provides the optimum predictions with respect to the GPS-derived vertical-displacement rates consists of an elastic lithosphere with a thickness of between 20 and 30 km, an asthenosphere viscosity between 1 and 2 · 10 18 Pa s, and a basal asthenosphere depth between 250 km and possibly greater than 400 km. We find that the very low asthenosphere viscosity values of ca. 10 17 Pa s sometimes suggested in the literature are not necessary to account for the rapid vertical-displacement rates observed, which are the result of the contemporary decrease in the mass of the ice cap not considered previously.

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“…Sjöberg et al (2004) Table 2), suggests that it is difficult to observe far from the thinning area by using gravimeters.…”

Section: Observations Of Deformation and Gravity Variationmentioning

confidence: 99%

“…Past and present-day ice thinning induce a deformation at the Earth surface that has been observed in GPS and gravity measurements close to the shrinking ice bodies (Pagli et al, 2007;Sato et al, 2006;Sjöberg et al, 2004;Khan et al, 2007). Knowing the current ice-thickness variations, from differential analysis of digital elevation models (DEMs), one can estimate the ground deformations and the gravity changes.…”

Section: Introductionmentioning

confidence: 99%

Ground deformation and gravity variations modelled from present-day ice thinning in the vicinity of glaciers

Mémin¹,

Rogister²,

Hinderer³

et al. 2009

Journal of Geodynamics

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To cite this version:A. Memin, Y. Rogister, J. Hinderer, M. Llubes, E. Berthier, et al.. Ground deformation and gravity variations modelled from present-day ice thinning in the vicinity of glaciers. Journal of Geodynamics, Elsevier, 2009, 48 (3-5) This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractThe solid Earth deforms because of post-glacial rebound due to the viscous relaxation following the last deglaciation but also because of present-day elastic deformation induced by ice thinning. In this paper, we compute elastic loading Green's function associated to the tilt of the ground in the vicinity of glaciers using a Love number formalism for a stratified non-rotating spherical Earth model. We compare this global approach with the plane approximation in terms of height, gravity and tilt changes as a function of the distance from the measurement point to the load. We find that Green's functions for the vertical displacement (resp. horizontal displacement, elastic part of the tilt) agree to within 1% up to ∼ 400 m (resp. 2 km, 5km) from the glaciers. A c c e p t e d M a n u s c r i p t Svalbard (Norway) glaciers by considering the ice model SVAL. We show that the rates of ground tilt are well above the limit of detection of up-todate long base hydrostatic tiltmeters, which, if installed next to the glaciers, could be used to monitor the time evolution of ice thinning. We also show that the topography has a strong influence on the gravity variations near the glaciers.

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Land uplift near Vatnajökull, Iceland, as observed by GPS in 1992, 1996 and 1999

Cited by 21 publications

References 18 publications

The lithosphere–asthenosphere boundary in the North-West Atlantic region

The lithosphere–asthenosphere boundary in the North-West Atlantic region

Glacial-isostatic Adjustment and the Viscosity Structure Underlying the Vatnajökull Ice Cap, Iceland

Ground deformation and gravity variations modelled from present-day ice thinning in the vicinity of glaciers

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