Öræfajökull is quite rare amongst Icelandic volcanoes because it erupts violently. Melting part of the ice-cap on its summit, this causes 'glacier-bursts', which rush down the volcano as enormous, and dangerous, floods. Such was a local priest's description of the 'glacier-burst' in 1727.
A Change of Name, 1362
Öræfajökull is the highest mountain in Iceland, and one of Europe's largest volcanoes. It rises to 2,119m, almost directly from near sea-level, and much of its summit is hidden beneath a glacial ice-cap, or jökull, covering 14km2. The featureless plains of southeastern Iceland at its feet are so isolated that it is claimed that no mice have ever found their way there. This, though, is one of the most sheltered parts of the country, even warm by Icelandic standards, with good pastureland and birch woods. But the area is called Öræfi, 'wasteland'; and the name of its dominating volcano means 'wasteland glacier'. These paradoxical names came about in 1362, when the volcano erupted violently and the whole neighbourhood became no more than a wasteland. Before its great eruption, the volcano had the less emotive name of Knappafell, 'the knobbly mountain', and its coastal fringe was called Litlahérad. Thus the new place names immortalized the disaster.
Rather unusual things happen when a volcano erupts under an ice-cap that lies in a large crater. The hot gases, steam and molten rock, expelled at temperatures of well over 750°C, melt the lower parts of the ice. The meltwater accumulates under the ice, fills the crater, and then suddenly gushes out from beneath the ice-cap and rushes downhill at great speed like a river in flood. For perhaps a day or more, the rate of discharge can be higher than that measured at the mouth of the River Amazon - about 100,000m3 per second! The meltwater carries along vast quantities of ice and rock fragments that are eventually laid down on huge deltas or plains at the foot of the volcano. Jökulhlaup, or 'glacier-burst', is the graphic Icelandic term used to describe these powerful events. Generally speaking, they lie somewhere between flooding streams carrying unusual amounts of mud and rocks, and mudflows carrying unusual amounts of water. It was such a glacier burst that devastated the coastal areas south and southwest of Öræfajökull in 1362.
If the eruption goes on long enough, the hot materials will melt all the ice lying directly above the volcanic chimney. The hot fragments can then be thrown straight into the open air and scattered over a wide area, as in a normal eruption. This is what happened in 1362, when an area stretching at least 100km northeast of the volcano was covered by a thick blanket of ash and pumice.
Some of the effects of this eruption were pieced together from the fragmentary records by the Icelandic volcanologist, S. Thórarinsson. Iceland is lucky in having a recorded history that stretches back to the initial Viking settlement in AD 874. These records include the famous sagas, monastic accounts and cartularies, which are inventories of church property. Many, of course, are incomplete, and some of the accompanying commentaries are fanciful in the extreme.
About 1340, a cartulary indicates that Litlahérad had a population of some 200 people. There were four main churches, and thirty, maybe as many as forty, farms. Many of these were subdivided and were virtually small hamlets. Sheep, cattle and horses thrived onthe pasturelands. Very few amongst this small coastal community lived through the devastation in 1362.
The oldest surviving record of the event is in the Annals of Skálholt, written at the Monastery of Mödruvellir in northern Iceland in the late fourteenth century.
A volcanic eruption...kept burning from the flitting days [early June] until the autumn with such monstrous fury that it laid waste the whole of Litlahérad, as well as Hornafjördur and Lónshverfi districts [75-100km to the northeast]. At the same time, there was a glacier-burst from Knappafell into the sea, carrying such quantities of rocks, gravel and mud that they formed...a plain where there had previously been 300 fathoms [55m] of water. Two parishes, Hof and Raudilaekur, were entirely wiped out. On even ground [people] sank up to mid-leg into the sand, and the wind swept it up into drifts so that buildings were almost obliterated. So much ash was carried over the northern areas of Iceland that footprints showed up in it. So much pumice could be seen floating off the west coast that ships could hardly make their way through it.
Other records later commented that all Litlahérad was devastated. In the course of a single morning, the glacier-burst tore nearly every farm from its foundations and swept them into the sea. The wooden church at Raudilaekur was one of the few buildings - perhaps the only one - to remain upright. The darkness was so intense that the roads could not be distinguished even at noon. The glacier-burst cut the routes to the west; and the main river to the east completely changed its course. Hot ash and pumice rained down on the shore. Those who survived the initial glacier-burst faced a hazardous journey of almost 100km before they could reach safety. Few, if any, completed the exodus. Several hundred people may have died altogether, and most of these probably drowned. It was said that the priest and deacon of Raudilaekur church were the sole survivors of the catastrophe, but other tales claimed that only an old woman and a mare were spared.
Öraefi was to remain a wasteland for almost a century. In later years, people settled again in some of the hamlets, but others were abandoned for ever. Eventually, the details of the catastrophe were forgotten, and only the place-name remained. But a folk memory lived on in a legend recorded during the first decade of the eighteenth century. It goes something like this:
Once upon a time, Hallur, the shepherd at the hamlet of Svinafell, had collected the ewes together, and the maids had started milking them, when they heard a loud noise come from Öræfajökull. They were astonished. Soon afterwards, there was another noise. Hallur said that they would be well advised not to wait for a third one. He immediately took refuge in Flosi's Cave, in the mountainside east of Svinafell. [It seems that the maids, unwisely, did not follow him, perhaps because they preferred to take their chances with the booming mountain.] Whilst Hallur was sheltering in the cave, the third noise duly came. It was the sound of the glacier-burst. It swept down every gully on the mountainside, and carried with it so much water and rock that they destroyed all the people and animals in the district except Hallur himself and a single horse with a blaze on its face.
Amongst a number of lessons that may be drawn from this story, the first is that it is best to climb up away from plains when a glacier-burst threatens; and another lesson is that, in such an eventuality, milkmaids should not hesitate to follow shepherds into caves.
Excerpted from Alwyn Scarth's Vulcan's Fury: Man Against The Volcano, Yale University Press, New Haven, 1999.