Subglacial flood path development during a rapidly rising jökulhlaup from the western Skaftá cauldron, Vatnajökull, Iceland

Einarsson, Bergur; Jøhannesson, Tómas; Þorsteinsson, Þorsteinn; Gaidos, Eric; Zwinger, Thomas

doi:10.1017/jog.2017.33

Cited by 18 publications

(28 citation statements)

References 47 publications

(114 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Recent research has identified that, like other rapidly-rising floods, some of the floods in Skaftá cannot be explained by Nye's (1976) jökulhlaup theory and instead the passage of a subglacial pressure wave forms the initial flood path (Einarsson et al, 2016a(Einarsson et al, , 2016b. This assertion supports other work on rapidly rising jökulhlaups, which have been identified in Iceland and elsewhere (e.g.…”

Section: Volcanically-generated Jökulhlaups In Icelandsupporting

confidence: 77%

A review of glacier outburst floods in Iceland and Greenland with a megafloods perspective

Carrivick

Tweed

2019

Earth-Science Reviews

View full text Add to dashboard Cite

The very largest glacier outburst floods have been termed 'megafloods' given their volume and peak discharge. That definition might be revised because those floods have become understood due to their distinctive and pervasive landscape impacts. At least three floods in Iceland can be categorized as megafloods since they produced impressive bedrock canyons and giant fluvially-transported boulders. Glacier lake outburst floods (GLOFs) in Greenland might also have megaflood-type attributes given the enormous lake volumes drained. We therefore here present the first review of glacier outburst floods in Greenland: sites Isvand, Russell Glacier, Kuannersuit Glacier, Lake Tininnilik, two unnamed lakes near Amitsulooq Ice Cap, and Iluliallup Tasersua, Base Camp Lake, Lake Hullett, Qorlortorssup Tasia, Imaersartoq, Tordensø, North Midternaes and an outlet glacier of the A. P. Olsen Ice Cap. Overall, megaflood-type landscape impacts in Iceland tend to be best-preserved and most easily identified inland although there has also been extensive offshore sedimentation. There are very few reported impacts of glacier outburst floods in Greenland. In Greenland ice-dam failure causes frequent flooding compared to the volcanically-triggered floods in Iceland and this combined with the proximity of the Greenland glacier lakes to the coast means that most proglacial channels in Greenland are flood-hardened and most landscape impact is likely to be offshore in estuaries and fjords. Future floods with megaflood-type attributes will occur in Iceland induced by volcanic activity. In Greenland they will be induced by extreme weather and rapid ice melt. Any potential landscape impact of these future floods remains open to question.

show abstract

Section: Volcanically-generated Jökulhlaups In Icelandsupporting

confidence: 77%

A review of glacier outburst floods in Iceland and Greenland with a megafloods perspective

Carrivick

Tweed

2019

Earth-Science Reviews

View full text Add to dashboard Cite

show abstract

“…At moderate elevations in our study area, this hypothesis appears to be inconsistent with late‐season ice deceleration that is generally associated with subglacial channelization because while ice velocity at these elevations begins to fall following the lake drainage event on day ~188, basal uplift continues to increase (Figures b–c; Bartholomew et al, ; Chandler et al, ; Hoffman et al, ). However, supraglacial drainage events, like fast‐rising jökulhlaups, are generally thought to occur so rapidly that subglacial channels cannot effectively develop in the vicinity of lake drainages and subglacial water flows as a turbulent sheet (Dow et al, ; Einarsson et al, ; Flowers et al, ; Werder & Funk, ). Increased subglacial efficiency, however, need not be confined to channelization alone (e.g., Andrews et al, ; Hoffman & Price, ; Meierbachtol et al, ).…”

Section: Discussionmentioning

confidence: 99%

Seasonal Evolution of the Subglacial Hydrologic System Modified by Supraglacial Lake Drainage in Western Greenland

et al. 2018

View full text Add to dashboard Cite

The impact of summer surface melt on Greenland Ice Sheet dynamics is modulated by the state of the subglacial hydrologic system. Studies of ice motion indicate that efficiency of the subglacial system increases over the melt season, decreasing the sensitivity of ice motion to surface melt inputs. However, the behavior of the subglacial hydrologic system is complex and some characteristics are still poorly constrained. Here we investigate the coevolution of subglacial hydrology and ice motion in the Pâkitsoq region of western Greenland during the 2011 melt season. We analyze measurements from 11 Global Positioning System stations, from which we derive ice velocity, longitudinal strain rates, and basal uplift, alongside observations of surface ablation and supraglacial lake drainages. We observe ice acceleration after the onset of local surface melting, followed by gradual ice deceleration, consistent with increasing subglacial efficiency. In the study area, supraglacial lake drainages cooccur with a change in regional strain rate patterns and ice deceleration, suggesting that lake drainages contribute to rapid subglacial reorganization. At lower ice surface elevations (below ~900 m above sea level), ice motion is correlated with both total basal uplift and its rate of change, while at higher elevations (~900–1,100 m above sea level), ice motion correlated only with the basal uplift rate. This pattern suggests that continued cavity growth or subglacial sediment dynamics may be important in the apparent increase in subglacial drainage efficiency at higher elevations in the ablation zone. Our results further suggest that transient subglacial behavior is important in the seasonal evolution of ice motion.

show abstract

“…Several following reports showed that rapidly-rising jökulhlaups are often observed (e.g. Einarsson and others, 2016, 2017), and can also occur in non-volcanic environments outside of Iceland (e.g. Grinsted and others, 2017).…”

Section: Introductionmentioning

confidence: 98%

Seismic characterization of a rapidly-rising jökulhlaup cycle at the A.P. Olsen Ice Cap, NE-Greenland

et al. 2020

View full text Add to dashboard Cite

Rapidly-rising jökulhlaups, or glacial outburst floods, are a phenomenon with a high potential for damage. The initiation and propagation processes of a rapidly-rising jökulhlaup are still not fully understood. Seismic monitoring can contribute to an improved process understanding, but comprehensive long-term seismic monitoring campaigns capturing the dynamics of a rapidly-rising jökulhlaup have not been reported so far. To fill this gap, we installed a seismic network at the marginal, ice-dammed lake of the A.P. Olsen Ice Cap (APO) in NE-Greenland. Episodic outbursts from the lake cause flood waves in the Zackenberg river, characterized by a rapid discharge increase within a few hours. Our 6 months long seismic dataset comprises the whole fill-and-drain cycle of the ice-dammed lake in 2012 and includes one of the most destructive floods recorded so far for the Zackenberg river. Seismic event detection and localization reveals abundant surface crevassing and correlates with changes of the river discharge. Seismic interferometry suggests the existence of a thin basal sedimentary layer. We show that the ballistic part of the first surface waves can potentially be used to infer medium changes in both the ice body and the basal layer. Interpretation of time-lapse interferograms is challenged by a varying ambient noise source distribution.

show abstract

Subglacial flood path development during a rapidly rising jökulhlaup from the western Skaftá cauldron, Vatnajökull, Iceland

Cited by 18 publications

References 47 publications

A review of glacier outburst floods in Iceland and Greenland with a megafloods perspective

A review of glacier outburst floods in Iceland and Greenland with a megafloods perspective

Seasonal Evolution of the Subglacial Hydrologic System Modified by Supraglacial Lake Drainage in Western Greenland

Seismic characterization of a rapidly-rising jökulhlaup cycle at the A.P. Olsen Ice Cap, NE-Greenland

Contact Info

Product

Resources

About