Glacier Surge Mechanism: 1982-1983 Surge of Variegated Glacier, Alaska

Kamb, Barclay; Raymond, C. F.; Harrison, W. D.; Engelhardt, Hermann; Echelmeyer, Κ. A.; Humphrey, N. F.; Brugman, Melinda M.; Pfeffer, T.

doi:10.1126/science.227.4686.469

Cited by 730 publications

(810 citation statements)

References 40 publications

Supporting

Mentioning

745

Contrasting

Unclassified

Order By: Relevance

“…In previous studies the existence of turbid water has been related to a collapse of a linked-cavity drainage system (Kamb, 1987) and hence an abrupt end of the surge (Kamb et al, 1985). By 2012 the surge had been active for at least 10 years before flow rates decreased substantially and NGS reached shallow sea bed.…”

Section: Front Velocities Advance Rate and Surge Terminationmentioning

confidence: 96%

“…(Meier and Post, 1969;Dolgoushin and Osipova, 1975;Clarke et al, 1984;Cuffey and Patterson, 2010). Based on studies from the temperate Variegated Glacier, Alaska, a hydraulic mechanism was proposed where surges are explained by switches between an efficient tunnel-based basal drainage system and slow linked-cavity system (Kamb et al, 1985;Kamb, 1987). Some surges display an abrupt speed-up and slow-down (days to weeks), while other glaciers go through slower (years-long) accelerations and decelerations.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Surge dynamics in the Nathorstbreen glacier system, Svalbard

2014

View full text Add to dashboard Cite

Abstract. Nathorstbreen glacier system (NGS) recently experienced the largest surge in Svalbard since 1936, and this was examined using spatial and temporal observations from DEM differencing, time series of surface velocities from satellite synthetic aperture radar (SAR) and other sources. The upper basins with maximum accumulation during quiescence corresponded to regions of initial lowering. Initial speed-up exceeded quiescent velocities by a factor of several tens. This suggests that polythermal glacier surges are initiated in the temperate area before mass is displaced downglacier. Subsequent downglacier mass displacement coincided with areas where glacier velocity increased by a factor of 100-200 times (stage 2). After more than 5 years, the joint NGS terminus advanced abruptly into the fjord during winter, increasing velocities even more. The advance was followed by up-glacier propagation of crevasses, indicating the middle and subsequently the upper part of the glaciers reacting to the mass displacement. NGS advanced ∼15 km, while another ∼3 km length was lost due to calving. Surface lowering of ∼50 m was observed in some up-glacier areas, and in 5 years the total glacier area increased by 20 %. Maximum measured flow rates were at least 25 m d −1 , 2500 times quiescent velocity, while average velocities were about 10 m d −1 . The surges of Zawadzkibreen cycle with ca. 70-year periods.

show abstract

Section: Front Velocities Advance Rate and Surge Terminationmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Surge dynamics in the Nathorstbreen glacier system, Svalbard

2014

View full text Add to dashboard Cite

show abstract

“…This reach is the lower part of a large ice fall that heads the glacier; it is evident in Figure 10 in terms of the high slopes and low ice thicknesses for x s -1.2 km. The high velocities there are due to rapid basal sliding, amounting to as much as 130m a· 1 , which was observed at the head of a tunnel driven to bedrock (Kamb and LaChapelle, 1968;Kamb, 1970, p. 706, example 4).…”

mentioning

confidence: 99%

Stress-Gradient Coupling in Glacier Flow: I. Longitudinal Averaging of the Influence of Ice Thickness and Surface Slope

1986

Self Cite

View full text Add to dashboard Cite

ABSTRACT. For a glacier flowing over a bed of longitudinally varying slope, the influence of longitudinal stress graruents on the flow is analyzed by means of a longitudinal flow-coupling equation derived from the •vertically" (cross-sectionaUy) integrated longitudinal stress equilibrium equation, by an extension of an approach originally developed by Budd (196g), Linearization of the flow-coupling equation, by treating the flow velocity ii ("vertically" averaged), ice thickness h, and surface slope a in terms of small deviations t:lii, llh, and Aa from overall average (datum) values ii 0 , h 0 , and ~· results in a differential equation that can be solved by Green's function methods, giving t:lii(x) as a function of M(x) and Aa(x), x being the longitudinal coordinate. The result has the form of a longitudinal averaging integral of the influence of local h(x) and a(x) on the flow u(x):where the integration is over the length L of the glacier. The A operator specified deviations from the datum state, and the term on which it operates, which is a function of the integration variable x' , represents the influence of local h(x' ), a(x' ), and channel-shape factor f(x' ), at longitudinal coordinate x' , on the flow ii at coorrunate x, the influence being weighted by the "influence transfer function• exp(-lx' -xl/1) in the integral. The quantity I that appears as the scale length in the exponential weighting function is called the longitudinal coupling length. lt is deter~ned by rheological parameters via the relationship I = 2h n{Ti/3'fl, where n is the flowlaw exponent, ii the effective longitudinal viscosity, and n the effective shear viscosity of the ice profile. ii is an average of the local effective viscosity n over the ice crosssection, and (l'lr 1 is an average of n-1 that gives strongly increased weight to values near the base. Theoretically, the coupling length I is generally in the range one to three times the ice thickness for vaUey glaciers and four to ten times for ice sheets; for a glacier in surge, it is even longer, J -12h. It is distinctly longer for non-linear (n • 3) than for linear rheology, so that the flow-coupling effects of longitudinal stress gradients are markedly greater for non-linear flow .The averaging integral indicates that the longitudinal variations in flow that occur under the influence of sinusoidal longitudinal variations in h or a, with wavelength >., are attenuated by the factor 1/(1 + (2nl/ >.) 2 ) relative to what they would be without longitudinal coupling. The short, intermediate, and long scales of glacier motion (Raymond, 19gO), over which the longitudinal flow variations are strongly, partially, and little attenuated, are for >. s 21 , 21 s >. s 201 , and >. ;;:; 201.

show abstract

“…2 and 10). The li thol ogy of these sedi ments and the basal pore-wa ter pres sure, which af fected the shear strength of the de pos its of the bed and the strength of the ice-bed cou pling, were di rectly re lated (see Kamb et al, 1985;Iverson et al, 1994Iverson et al, , 1995Piotrowski et al, 2004;Ev ans et al, 2006). The subglacial wa ter pres sure de pended on the rate of melt wa ter sup ply, but also on the granulometry of the sed i ments, which in flu enced the per me abil ity of the ice sheet sub stra tum (Boulton and Jones, 1979;Boulton et al, 2001;Piotrowski et al, 2004;Rob erts and Hart, 2005;Piotrowski et al, 2006).…”

Section: The Influence Of the Substratum's Lithology On The Lobe Devementioning

confidence: 99%

Basal till and subglacial conditions at the base of the Upper Odra ice lobe (southern Poland) during the Odranian (Saalian) Glaciation

Salamon

2014

View full text Add to dashboard Cite

Salamon, T., 2014. Basal till and subglacial con di tions at the base of the Up per Odra ice lobe (south ern Po land) dur ing the Odranian (Saalian) Gla ci ation. Geo log i cal Quar terly, 58 (4): 779-794, doi: 10.7306/gq.1176The ob jec tive of this con tri bu tion is de tail char ac ter is tics of the basal till and the con di tions at the base of the Up per Odra ice lobe. The lobe was formed in a foremountain area. Its cen tral part was a Niemodlin Plain and the W part of the Racibórz Basin, sur rounded by ar eas that have a much more var ied re lief. Par tic u lar at ten tion is paid to the con di tions at the ice sheet base, gen er at ing the dy nam ics of gla cier move ment. The study is based on anal y sis of the basal till. Three sites with basal till ly ing on dif fer ent types of sub stra tum (typ i cal for the study area) are pre sented. The basal till of the Up per Odra ice lobe is char ac ter ized by spa tial vari a tions. Dif fer ent in ten si ties of its de for ma tion in di cate that large lat eral dif fer ences in con di tions oc curred in the lobe sub stra tum. The li thol ogy con trolled the rate of basal wa ter pres sure, and thus the strength of both the subglacial sed i ments and the ice-bed cou pling. Var i ous strain rates in the till pro files in di cate that the con di tions at the ice sheet base also changed with time. The ice sheet was highly mo bile, even on the coarse-grained sub stra tum. The low perme abil ity of the Qua ter nary sub stra tum, and the rel a tively small thick ness of the Qua ter nary sands and grav els re sulted in a high wa ter pres sure at the ice sheet base. The move ment of the Up per Odra ice lobe was con cen trated in the basal zone of the ice sheet. The main mech a nisms of mo tion were slid ing and de for ma tion of the subglacial sed i ments. The de for ma tion oc curred in re stricted ar eas only, and did not have a per va sive char ac ter.

show abstract

Glacier Surge Mechanism: 1982-1983 Surge of Variegated Glacier, Alaska

Cited by 730 publications

References 40 publications

Surge dynamics in the Nathorstbreen glacier system, Svalbard

Surge dynamics in the Nathorstbreen glacier system, Svalbard

Stress-Gradient Coupling in Glacier Flow: I. Longitudinal Averaging of the Influence of Ice Thickness and Surface Slope

Basal till and subglacial conditions at the base of the Upper Odra ice lobe (southern Poland) during the Odranian (Saalian) Glaciation

Contact Info

Product

Resources

About