Hekla
Hekla is a volcano located in the south of Iceland at 63.98 N, and 19.70W, with a height of 1,491 meters (4,890 ft). Hekla is Iceland's most active volcano; over 20 outbreaks having occurred in and around the volcano since 874. During the Middle Ages, Icelanders called the volcano the "Gateway to Hell."
Hekla is part of a volcanic ridge, 40 kilometers (25 miles) long. However, the most active part of this ridge, about 5 km (3 mi)long, is considered to be the volcano Hekla proper. Looking rather like an overturned boat, with its keel being in fact a series of craters, two of which are generally the most active.
Icelandic stamp depicting the 1947 eruption
The earliest recorded eruption of Hekla took place in the
ninth century, although very likely there had been
many before that date. Since then there have been between twenty
and thirty considerable eruptions, with the mountain sometimes remaining active for periods of six years
with little pause. Hekla took a long rest of more
than sixty years duration prior to 1845, when it suddenly
burst forth on September 2 (Anonymous, 1872):
- After a violent storm on the night of the 2nd of September in that year, the surface of the ground in the Orkney Islands was found strown with volcanic dust. There was thus conveyed to the inhabitants of Great Britain an intimation that Hecla (sic} had been again at work. Accordingly, tidings soon after arrived of a great eruption of the mountain. On the night of the 1st of September, the dwellers in its neighbourhood were terrified by a fearful underground groaning, which continued till mid-day on the 2nd. Then, with a tremendous crash, there were formed in the sides of the cone two large openings, whence there gushed torrents of lava, which flowed down two gorges on the flanks of the mountain. The whole summit was enveloped in clouds of vapour and volcanic dust. The neighbouring rivers became so hot as to kill the fish, and the sheep fled in terror from the adjoining heaths, some being burnt before they could escape.
- On the night of the 15th of September, two new openings were formed — one on the eastern, and the other on the southern slope — from both of which lava was discharged for twenty-two hours. It flowed to a distance of upwards of twenty miles, killing many cattle and destroying a large tract of pasturage. Twelve miles from the crater, the lava-stream was between forty and fifty feet deep and nearly a mile in width. On the 12th of October a fresh torrent of lava burst forth, and heaped up another similar mass. The mountain continued in a state of activity up to April 1846; then it rested for a while, and began again in the following month of October. Since then, however, it has enjoyed repose.
- The effects of these eruptions were disastrous. The whole island was strown with volcanic ash, which, where they did not smother the grass outright, gave it a poisonous taint. The cattle that ate of it were attacked by a murrain, of which great numbers died. The ice and snow, which had gathered about the mountain for a long period of time, were wholly melted by the heat. Masses of pumice weighing nearly half a ton were thrown to a distance of between four and five miles.
Eruptions in Hekla are extremely varied and difficult to predict. Some are very short (a week to ten days) whereas others can stretch into months and years (the 1947 eruption started
March 29,
1947 and ended April 1948).
The most recent eruption was on February 28, 2000.
Report on this last eruption in January, 2003: Up until now, it has always been assumed that Hekla was incapable of producing that most dangerous of volcanic phenomena, the pyroclastic flow. Now, however, at team from the Norwol Institute in Reykjavík (see link below), under the leadership of Dr. Ármann Höskuldsson, has reported that they have found traces of a small pyroclastic flow, roughly 5 kms long, stretching down the side of the mountain. This will call for a reappraisal of volancic eruptions of the basic rock type, which up to now were generally admitted never to produce pyroclastic flows. It will also require that the public and curious spectators who always rush to the scene at the start of a new outbreak, to be kept much further away from the volcanic activity than was thought necessary during previous outbreaks.
Eruptions in historical times:
2000-1991-1980-1970-1947-1845-1766-1693-1636-1597-1510-1434-1389-1341-1300-1222-1206-1158-1104.
Main eruptions in prehistoric times:
H5: -6.600 years ago, H4:-4.000, H3:-2.800, H2:~A.D.860
References
Some of this text is based on the book "Wonders of Creation - A Descriptive Account of Vulcanoes and Their Phenomena", Anonymous, 1872. See [1]
External link