Torfajokull

from Wikipedia, the free encyclopedia
Torfajokull
Vondugil and Háalda

Vondugil and Háalda

height 1190  m
location Iceland
Coordinates 63 ° 53 '39 "  N , 19 ° 0' 37"  W Coordinates: 63 ° 53 '39 "  N , 19 ° 0' 37"  W.
Torfajokull (Iceland)
Torfajokull
Type Subglacial volcano
rock Rhyolite
Last eruption 1477
Kaldaklofsfjöll

Kaldaklofsfjöll

Template: Infobox Berg / Maintenance / BILD1
Torfajokull area
Laugahraun
In the Torfajökull area, in the background the Bláhnúkur
Obsidian in the Laugahraun lava field
Rock at Torfajokull

The Torfajökull is a 1,190 meter high active volcano in southern Iceland , north of Mýrdalsjökull . It is only partially covered by the eponymous glacier with an area of ​​15 km². The warm springs of Landmannalaugar and Hrafntinnusker belong to his area . Torfajökull is located in the municipality of Rangárþing ytra and Skaftárhreppur .

Shape and appearance of the volcano

The 12 km × 18 km caldera of Torfajökull was created by the collapse of a magma chamber during a huge eruption during the last ice age .

The area of ​​Torfajökull includes the 100 km² largest high temperature area in Iceland, the largest rhyolite area in Iceland with an area of ​​approx. 350 km² and extensive obsidian lava flows.

The volcano is an exception among Iceland's central volcanoes as the ratio of rhyolite to basalt lavas in its area is 4: 1, as opposed to the ratio of 1: 5 in most of the other central volcanoes in the country.

Outbreak story

Ice age

The oldest recorded eruptions took place in the Torfajökull system about 100,000 years ago, ie during the last ice age . While in developed interglacials Rhyolithlaven and appropriate tephra layers.

In the colder periods, the mountains formed under glaciers along a system of crevasses surrounding the caldera, which at the beginning of the 21st century represent the edge of the caldera. These are z. B. around Rauðufossafjöll , Bláhnúkur , Torfajökull glacier . Many of them are rhyolite lava domes, such as Brennisteinsalda . Some of these mountains penetrated the ice sheet and became tabular volcanoes, such as the z. B. is the case with the southeastern Rauðufossafjöll, which belong to the rare rhyolite tabular volcanoes.

Modern eruptions

The last three recorded series of eruptions were linked to those in the Bárðarbunga system, provided that the nearby Veiðivötn such as the geologist Halldór Kjartansson are included in this system.

Around the year 200

1800 years ago, the Dómadalshraun lava field was formed in the Torfajökull system and is made up of basalt and rhyolite laves . At the same time, the Hnausagígar craters in the Veiðivötn system produced basalt lavas . Interestingly, the eruption sites in both systems are arranged in a row. In fragments of the tephra of these eruptions one finds Felsic , i.e. H. SiO 2 -rich pumice with mafish , d. H. basaltic ashes are baked.

871

In 871 the next known eruption occurred. This created a very characteristic ash layer, the so-called land acquisition ash layer (isl. Landnámslag ). The series of outbreaks began in the Torfajökull system. Subsequently, there were very strong eruptions in the Bárðarbunga system, which created the Vatnaöldur crater series . During these volcanic events, both rhyolitic, light ashes fell, which form the lower layer of this ash layer, as well as basaltic, dark ashes that lay on top.

This striking two-tone layer of ash is used in tephrochronology , especially since it was created around the time when Iceland was first settled. An example can be seen as a cross-section through layers of the earth, for example in ðjóðminjasafn , the National Museum of Iceland in Reykjavík .

Some lava fields were also produced, including the Hrafntinnuhraun .

1477

The last eruptions in the area occurred in 1477. This series began in the area of Veiðivötn with strong explosive eruptions, which then turned into an effusive phase. The Maar Ljótipollur and the crater Stútur were active, whereby u. a. the Norðurhraun lava field was created.

To the south of it there were simultaneous eruptions in the Torfajökull area. The SiO 2 -rich obsidian laves of the Suðurhraun and Laugahraun between the hut of Landmannalaugar and the Brennisteinsalda volcano date from this period.

It is believed that these eruptions were triggered by the volcanic eruptions in the area of ​​Veiðivötn, which in turn belong to the volcanic system of Bárðarbunga , which lies roughly parallel to the system of Torfajökull and B. at Landmannalaugar borders on this.

Rivers

The water from the glacier flows into the Markarfljót and the Tungnaá , among others .

Laugavegur trekking path

The well-known Laugavegur trekking path leads over the glacier. Many hot springs can be found on the way at Hrafntinnusker. Most of them are clay or sulfur springs as well as at the foot of the volcanic mountain Brennisteinsalda , which is part of the caldera rim. Large obsidian lava fields accompany the route, such as the Laugahraun near Landmannalaugar .

See also

Web links

Commons : Torfajökull  - collection of images, videos and audio files

Individual evidence

  1. Thor Thordarsson, Armann Hoskuldsson: Classic Geology in Europe 3. Iceland. Harpenden, Terra, 2002, p. 179
  2. Thor Thordarsson, Armann Hoskuldsson: Classic Geology in Europe 3. Iceland. Harpenden, Terra, 2002, p. 181
  3. ^ H. Tuffen, ea: Physical volcanology of a subglacial-to-emergent rhyolite tuya at Raudafossafjoll, Torfajokull, Iceland The Geological Society of London, 2002 Accessed: August 25, 2010
  4. http://www.agu.org/meetings/cc02babstracts/Mortensen-p.pdf AK Mortensen: Volcanic input from the short-lived plinian 871AD Settlement Event, Southern Iceland , undated
  5. Árný Sveinbjörnsdóttir: 14C aldursgreiningar á landnámi Íslands. IN: Jarðfræðafélag Íslands: Vorráðstefna 2003. Ágrip érinda og veggspjalda. April 23, 2003 p. 12 (PDF file; 807 kB) (Icelandic)
  6. ^ Halldór Kjartansson: The Icelandic basement , in: Ari Trausti Guðmundsson : Lebende Erde. Facets of the geology of Iceland. Reykjavík, Mál og Menning, 2007, p. 52 ff.