Did you know
Did you know | Questions and answers
How much ice melts annually where the glacier snouts reach down into the outwash plains by Hornafjörður?
Nearly 10 metres.
What is the likely maximum velocity of glacier snouts above Hornafjörður?
It could be approximately 1 m every 24 hours. The greatest velocity is where the glacier is steep, thick and cramped. The ice flows fastest at the surface of the glaciers middle, but at the base and margin the ice meets resistance. Glaciers are often thickest at the firn line, where they are quite steep, as firn is discharged there from the entire accumulation area. In the ablation area, the velocity of the glacier decreases, as less ice needs to be discharged. At this point, ice melts and runs off the glacier. The flow at the glaciers base is greatest where water pressure is high under the glacier. The highest flow rates occur during surges.
Is it likely that glaciers move faster during summer than in winter?
Yes. The flow at the base of glaciers depends on waterflow, which is greater in summer than in winter. There are known examples of increased flow in heavy rain.
Where would you look for a backpack you forgot during the autumn in a glacier’s accumulation area?
If it has snowed over, it is borne a long way down the flowline and emerges in the ablation area. Aircraft, which have crashed on the top of glaciers, have emerged at the snouts. If you lose the backpack in the ablation area, you should find it in the same place the following summer.
Where can crevasses be expected? How deep are they?
Crevasses form when tension rips the ice apart. They form across elevations, when the ice travels across elevation in the underlying landscape. The topmost crevasse can be dangerous when hiking down the glacier, as it does not come into sight until the hiker is almost at the brink. Over vertical cliffs there are ice falls, as gaps are formed in the glacier when it comes lose from vertical cliffs. When a glacier flows down a mountain slope, it is torn apart by frictional resistance, so that crevasses are directed approximately 45° upwards from the slope. If crevasses from both sides of the glacier are connected in its centre, they are shaped like a horseshoe. Longitudinal crevasses are formed when a glacier spreads out on lowland. Crevasses are rarely more than 20-30 m deep. At the depth, the ice is compressed by its own weight. The most dangerous crevasses are those, which are concealed under snow in the accumulation area or under recently fallen snow.
How long does it take water to flow from the Grímsvötn volcano down to the Skeiðarársandur outwash plain in glacial bursts?
At the peak flow rate of a glacial burst in Grímsvötn, the water could cover this 50 km distance in 3-5 hours.
How old is the oldest ice in Vatnajökull?
The oldest ice emerges at the margins of the ice cap after having been buried at the top and discharged near the base. Age determination of ash layers by glacier snouts shows that there is still ice in Vatnajökull from approximately AD 1200 and possibly earlier.
When was Vatnajökull formed?
During the last glacial epoch, which ended approximately 10,000 years ago, and in the following 1,000 years, ice retreated quickly from most of Iceland. It is believed that 2,500 years ago glaciers only existed in Iceland in the highest mountains, as the mean annual temperature was 2-3°C higher than today.
Following this period, the climate cooled and precipitation increased. Glaciers began to grow and flow down from the highest mountains, converging and forming the main ice caps still existing today, i.e. Vatnajökull, Langjökull, Hofsjökull and Mýrdalsjökull. The peak of their size was reached in the late 19th century, at the close of a cold period spanning several centuries.
How fast does erosion occur under Vatnajökull?
The ground under Vatnajökull is believed, to be dug approximately 3-4 mm each year and from each square kilometer thousands of tons of sediment are discharged annually. During glacier bursts and surges, the discharge rate is much higher. Each glacier burst in Grímsvötn, lasting for several days, discharges 30-150 million tons. During the burst of the Brúarjökull glacier in 1963-1964, the discharge of the glacial river Jökulsá á Brú amounted to 25 million tons, corresponding to a 14 mm annual subsidence of the glacier’s base. However, no glacier base has undergone such rapid abrasion as that of the eastern tongue of the Breiðamerkurjökull glacier when it advanced during the cold period between AD 1200 and 1900. During that time, the base subsided at an annual average of 10-20 cm.
Why is glacial ice blue?
The blue colour of icebergs in crevasses and ice caves is intriguing. Its spectrum spans everything from aquamarine to deep blue. The eye perceives clear ice as blue because as the light travels through the ice, its red, yellow and green components fade, while the blue colour travels the furthest. Sunlight needs to penetrate several metres of ice for this effect to emerge. This is why the domes of ice caves are blue. Bubbly ice, on the other hand, appears white, as the multifarious light reflected from the sides of the bubbles outweighs the single blue colour.
- surface area of 8,100 km²
- earth’s largest ice cap outside the polar regions
- average thickness of over 400 metres
- the highest and the lowest surfaces in Iceland
- the warmest and the coldest places in Iceland
- the wettest and the driest parts of Iceland
Hvannadalshnjúkur in Öræfajökull, a part of Vatnajökull, is the highest mountain peak in Iceland (2119 metres). Just eastwards, however, the Breiðamerkurjökull outlet glacier has carved a deep valley whose floor reaches some 300 metres below sea level.
Grímsvötn is within Vatnajökull and is the most active Icelandic volcano, but not far to its northwest the glacier reaches its maximum thickness of about 950 metres.
Whereas the area with Iceland’s highest precipitation is found by Kvísker, just south of Vatnajökull, the driest area in the country lies north of Breiðabunga, in the east part of Vatnajökull.
History of the exhibition
The Glacier exhibition in Höfn has been open for several years now. In the summer of 2000 there was an exhibition in Sindrabæ in Höfn as a part of the programme of Reykjavík - European City of Culture. The exhibition proved itself and was moved in the year 2002 in a more suitable housing, a former warehouse. In the spring of 2005 it was reopened after drastic improvements.
The idea of a glacier museum is not old. It can be traced back to a speech that Helgi Björnsson, a glacier expert from the scientific foundation of the University of Iceland, gave about a glacier museum in Hornafjörður in the year 1998. The idea is based upon two factors. First, to bring more knowledge about glaciers, nature and the locations around them, in a more appealing way than before. Second, to build up entertainment for tourists in Hornafjörður, involving the town itself, because it’s built in one of the most beautiful landscapes on the island. With the glacier exhibition new opportunities are created for a powerful international cooperation involving glaciology.
The position of the exhibition in Höfn í Hornafirði is geologically correct. Höfn is built in the surroundings of a dramatic mountain circle, where the outlet glaciers of Vatnajökull reach out to the community. Recently the national park Skaftafell was expanded and a big part of Vatnajökull is now a part of the national park.
The main purpose of the exhibition is to expand and bring more knowledge about glaciers and the effects they have on the country and its people. This purpose will be gained by:
- Running Ís-land, the glacier exhibition in Höfn in a lively and interesting way, for example with changeable exhibitions and lectures, seminars and more.
- Offering culturally connected traveling services with specifics.
- Collecting and deliver knowledge about the glaciers, how they appear and the effects on the way they appear, for example on the land, nature and weather.
- Collecting and deliver the history and culture that connects the glaciers, and life close to them.
- Encouraging more scientific explorations and researches related to the glacier.
- Working side by side with other foundations and organizations that care about these materials both in this country and abroad.