| 1. |
- Ingolfsson, Olafur, et al.
(author)
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Glacial geological studies of surge-type glaciers in Iceland — Research
- 2016
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In: Earth-Science Reviews. - : Elsevier BV. - 0012-8252. ; 152, s. 37-69
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Journal article (peer-reviewed)abstract
- Surging glaciers are potential analogues for land-terminating palaeo-ice streams and surging ice sheet lobes, and research on surge-type glaciers is important for understanding the causal mechanisms of modern and past ice sheet instabilities. The geomorphic signatures left by the Icelandic surge-type glaciers vary and range from glaciotectonic end moraines formed by folding and thrusting, crevasse-squeeze ridges, concertina eskers, drumlins and fluted forefields, to extensive dead-ice fields and even drift sheets where fast ice-flow indicators are largely missing. We outline some outstanding research questions and review case studies from the surge-type outlets of Brúarjökull, Eyjabakkajökull and Tungnaárjökull (Vatnajökull ice cap), Múlajökull and Sátujökull (Hofsjökull ice cap), Hagafellsjökull and Suðurjökull (Langjökull ice cap), Kaldalónsjökull, Leirufjarðarjökull and Reykjarfjarðarjökull (Drangajökull ice cap), as well as the surge-type cirque glaciers in northern Iceland. We review the current understanding of how rapid ice flow is sustained throughout the surge, the processes that control the development of the surge-type glacier landsystem and the geological evidence of surges found in sediments and landforms. We also examine if it is possible to reconstruct past surge flow rates from glacial landforms and sediments and scale-up present-day surge processes, landforms and landsystems as modern analogues to past ice streams. Finally,we also examine if there is a climate/mass-balance control on surge initiation, duration and frequency.
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| 2. |
- Schomacker, Anders, et al.
(author)
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Late Holocene and modern glacier changes in the marginal zone of Solheimajokull, South Iceland
- 2012
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In: Jökull: Journal of the Glaciological and Geological Societies of Iceland. - 0449-0576. ; 62, s. 111-130
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Journal article (peer-reviewed)abstract
- The forefield of the Solheimajokull outlet glacier, South Iceland, has a variety of glacial landforms and sediments that are products of late Holocene and modern glacier oscillations. Several sets of moraine ridges reflect past ice front positions and river-cut sedimentary sections provide information about past environments. Here, we describe sediments and landforms deposited during the late Holocene. Chronology is obtained by C-14 dating and cosmogenic exposure dating. The age determinations suggest that Solheimajokull had major advances in the late Holocene prior to the Little Ice Age, and more restricted advances during the Little Ice Age, after AD 1539. Oscillations of the Solheimajokull ice margin between 1938 and 2010 are documented by aerial photographs. Digital elevation models were produced from selected years in order to quantify ice thickness changes at the glacier margin over the last 50 years. The glacier margin thickened 70-100 m front 1960 to 1996 and then thinned 120-150 m between 1996 and 2010. In 2010, the glacier snout was 20-40 in thinner than in 1960. Additionally, the DEM time-series detect areas of erosion and deposition in the forefield.
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| 3. |
- Schomacker, Anders, et al.
(author)
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Postglacial relative sea level change and glacier activity in the early and late Holocene: Wahlenbergfjorden, Nordaustlandet, Svalbard
- 2019
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In: Scientific Reports. - : Springer Nature. - 2045-2322. ; 9:1
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Journal article (peer-reviewed)abstract
- Sediment cores from Kløverbladvatna, a threshold lake in Wahlenbergfjorden, Nordaustlandet, Svalbard were used to reconstruct Holocene glacier fluctuations. Meltwater from Etonbreen spills over a threshold to the lake, only when the glacier is significantly larger than at present. Lithological logging, loss-on-ignition, ITRAX scanning and radiocarbon dating of the cores show that Kløverbladvatna became isolated from Wahlenbergfjorden c. 5.4 cal. kyr BP due to glacioisostatic rebound. During the Late Holocene, laminated clayey gyttja from lacustrine organic production and surface runoff from the catchment accumulated in the lake. The lacustrine sedimentary record suggests that meltwater only spilled over the threshold at the peak of the surge of Etonbreen in AD 1938. Hence, we suggest that this was the largest extent of Etonbreen in the (mid-late) Holocene. In Palanderbukta, a tributary fjord to Wahlenbergfjorden, raised beaches were surveyed and organic material collected to determine the age of the beaches and reconstruct postglacial relative sea level change. The age of the postglacial raised beaches ranges from 10.7 cal. kyr BP at 50 m a.s.l. to 3.13 cal. kyr BP at 2 m a.s.l. The reconstructed postglacial relative sea level curve adds valuable spatial and chronological data to the relative sea level record of Nordaustlandet.
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| 4. |
- Svennevig, Kristian, et al.
(author)
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Uncovering a 70-year-old permafrost degradation-induced disaster in the Arctic : the 1952 Niiortuut landslide tsunami in central West Greenland
- 2022
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In: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 859
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Journal article (peer-reviewed)abstract
- On December 15th 1952, at approximately 14:00 local time a mass of 5.9 × 106 m3 of permafrozen talus deposits failed in a landslide close to the Niiortuut mountain on the south coast of the Nuussuaq peninsula, central West Greenland. Between 1.8 and 4.5 × 106 m3 of the material entered the sea and generated a tsunami that propagated through the Vaigat strait (Sullorsuaq). Here we describe this catastrophic event for the first time by analysis of historical material supplemented by recent fieldwork and discuss the implications for the state of contemporary permafrozen slopes. The tsunami killed a fisherman working on the shore of southern Nuussuaq, 10 km south-east of the landslide. In the mining town of Qullissat, 30 km south of the landslide, it had a runup height of 2.2–2.7 m and caused minor material damage. Morphological evidence show that the basal surface of rupture was 80 m inside the permafrost cemented talus slope, whose degradation was a dynamic conditioning factor for the landslide. The 1952 Niiortuut landslide is the first historically recorded event of permafrost degradation induced landslide-tsunamis in the Arctic. We infer that the landslide and its cascading consequences occurred due to the early-twentieth century warming that started in the late 1910's in the Arctic. Warming is now increasingly affecting this region, as shown by an enhanced recent landslide activity.
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