Gjálp
| Gjálp | ||
|---|---|---|
| location | Iceland | |
| Mountains | Vatnajokull | |
| Coordinates | 64 ° 30 '34 " N , 17 ° 22' 12" W | |
|
||
| Type | Subglacial volcano , crevice volcano | |
| Last eruption | 1996 | |
 Remains of the bridge on Skeiðarársandur, which was destroyed in 1996 |
||
Gjálp is a subglacial crevice volcano under the Vatnajökull glacier in southeast Iceland .
Surname
The name of the volcano Gjálp comes from Norse mythology . Gjálp is the name of one of the daughters of the giant Geirröðr in the Skáldskaparmál of the Prose Edda by Snorri Sturluson .
Position and shape
The eruption fissure is located between two large volcanoes under the ice of Vatnajökull, which is one of the largest glacier shields in Europe. Gjálp is about halfway between the central volcanoes Bárðarbunga and Grímsvötn , but is assigned to the system of the latter.
The roughly seven kilometers long volcanic fissure is roughly parallel to the main direction of the rift zones and the active volcanic zones in Iceland, i.e. it is oriented from southwest to northeast.
Eruption story
After a first eruption in 1938, the volcano made itself felt again through an eruption from September 30th to November 5th, 1996.
The eruption turned out to be an interaction of three volcanoes, whereby the central volcano of the Grímsvötn, however, played a more passive role as a collecting basin for the melt water, especially from the Gjálp.
Scientists from various universities found a connection between a directly preceding strong earthquake in the neighboring central volcano Bárðarbunga (5.4 on the Richter scale ) and the eruption in Gjálp. Accordingly, the caldera of the Bárðarbunga would have sunk as a whole in the earthquake. The pressure would have triggered the volcanic eruption in Gjálp, which in turn initiated a kind of chain reaction to run the glacier over the Grímsvötn below .
Initially, the eruption took place under a 400 to 600 m thick ice sheet. The eruption broke through the glacial ice on October 2, 1996, producing a column of eruption and at the same time caused a large amount of meltwater to flow towards the subglacial lake at the Grímsvötn volcano . It took a few more weeks, however, until the lake was filled, which u. a. as a tremor indicator on the seismometers on the night of November 4th to 5th, 1996. The amount of water finally broke through the ice barrier in front of it and tidal waves from 5 to 7 May. November 1996 as so-called Jökulhlaup poured down under the Skeiðarárjökull valley glacier , which floated on the water, down and onto the upstream sander plains . The floods mainly used the existing waterways on the Sander, i. H. that of the Skeiðará and Gígjukvísl rivers, and to a much lesser extent that of the Núpsvötn . At its peak, the tidal wave reached 45,000 cubic meters per second.
The ring road over the Sander was badly damaged by the course of the glacier.
On November 6, 1996, there was a brief eruption in the neighboring volcano Bárðarbunga , which was apparently caused by an intrusion from Gjálp.
See also
literature
- Hjörleifur Guttormsson, Oddur Sigurðson: Leyndardómur Vatnajökuls. Viðerni, fjöll and byggðir. Stórbrotin náttúra, eldgos og jökulhlaup. Reykjavík (Fjöll og firnindi) 1997 ISBN 9979-60-325-9
Web links
- Vulkanolog. Institute, Univ. Iceland (English)
- Film Það er ei nema eldur og ís (There's nothing but fire and ice): Film about volcanism in Iceland, especially Gjálp / Grímsvötn 1996 and Kraflaeldur 1975-84, video with Icelandic commentary
Individual evidence
- ↑ Snorri Sturluson, Friedrich Rühs: The Edda. Berlin 1812, p. 248. Accessed: August 24, 2010.
- ↑ cf. also: Hjörleifur Guttormsson, 1997, p. 24
- ↑ a b c The Gjálp eruption in Vatnajökull 30/9 - 13/10 1996. Accessed: 23 August 2010.
- ↑ a b Gjálp. Accessed August 23, 2010
- ^ Hjörleifur Guttormsson, 1997, p. 21
- ↑ Hjörleifur Guttormsson, 1997, p. 20
- ↑ http://rses.anu.edu.au/highlights/view.php?article=54 Retrieved December 30, 2010
- ↑ cf. Hjörleifur Guttormsson, 1997, p. 34f.