Jordrystelser begyndte I går under vulkanen Bárðarbunga, der ligger under den nordvestlige del af Vatnajökull – isbræen. Rystelserne fortsætter i øjeblikket og det tyder på starten af en såkaldt subglacial eruption i vulkanen, d.v.s. et udbrud under isen af Vatnajøkull. Der var udbrud i Bárðarbunga I året 1797, og et andet udbrud fandt sted I 1910, dog i den nærliggende vulkan Hamarinn, som tilhører samme vulkankomplekse system.
Bárdarbunga Vulkanen betragtes som en såkaldt skjoldvulkan, d.v.s. bred og flad i det men ca. 2000 meter og dens udbrudstype er både af eksplosiv og mere rolig karakter, alt afhængigt af smeltet tilførsel af magma og gasundvigelse i forbindelse med smeltning af isdækket, der ligger oven over vulkanen.
”Magmaen bevæger sig under jordskorpen og vores målinger viser, at der sker noget”, udtaler Gunnar Guðmundsson, Politiet har øget beredskabet og overvåger situationen tæt. Myndighederne bereder sig på et muligt udbrud og beredskabet er klar til at sikre kommunikation og information.
Leder af civilforsvaret i Island Víðir Reynisson siger, at der er stor sandsynlighed for et udbrud i Bárðarbunga, som ligger under gletsjeren Vatnajökull. Et vulkanudbrud under gletsjeren kan give lokale oversvømmelser og medføre askeskyer i op til 10–20 km højde, hvor de kan være en risiko for den nordatlantiske flytrafik.
Gunnar Guðmundsson: ”Vi har endnu ikke set nogle udbrud. Men hvis magmaen kommer op til overfladen under gletsjeren, vil den være eksplosiv, og så kan der opstå store askeskyer”.
I 2010 lammede vulkanen Eyjafjallajökull den europæiske flytrafik og forstyrrede de transatlantiske ruter i flere uger med en enorm askesky.
Kilde: Henning Andersen
vulkaneksperten.dk
Kilde: Nordic Volcanological Institute, Reykjavik, Island
GPS coordinates: 64°25’12” N, 17°19’48” W Max. elevation: 1725 m.a.s.l.
Grimsvötn volcano, situated near the center of the Vatnajökull ice cap in central Iceland, is one of Iceland’s most active volcanoes. It has a complex of calderas (Gudmundsson and Milsom, 1997), and a subglacial caldera lake sustained by geothermal heat. Small eruptions have occurred at the volcano in 1983 and 1998 (around 0.1 km3). In 1996, the Gjálp subglacial eruption occurred north of the volcano (Gudmundsson et al., 1997).
Kilde: “Norvulk” Nordic Volcanological Institute Reykjavik, Island
The Vatnajökull glacier is a temperate glacier covering about 8300 km2 in the SE part of Iceland. Volcanic fissure systems of the Mid-Atlantic Ridge plate boundary are partly covered by the western part of the ice sheet. Two major volcanic centers lie beneath the ice, the Bardarbunga volcanic centre and the Grimsvötn volcanic centre, both with large subglacial caldera depressions. The Bardarbunga centre is a part of a fissure system extending over 100 km to the south and some 50 km to the north of the glacier. The last eruption within the Bardarbunga centre occurred in 1910, but eruptions on the fissure system have occurred in 871 AD, 1477 AD and 1862 AD, all producing substantial amounts of lava. The Grimsvötn centre is the more active of the two with an eruption frequency during past centuries close to one eruption per decalast eruption occurred in 2011. As Bardarbunga, the Grimsvötn centre is a part of a a fissure system which includes the Laki fissure, which in 1783 produced about 12-14 km3 of basaltic lava. Within the ice filled Grimsvötn caldera intense geothermal activity continuously melts the ice to form a subglacial lake, which at intervals of 5 to 10 years is emptied along subglacial channels to create large floods (jökulhlaup) on the sandur plain, Skeidararsandur, on the Icelandic south coast.
Kilde: volcanolive.com John Seach
Iceland
64.63 N, 17.53 W
summit elevation 2000 m
stratovolcano(keglevulkan)
Bardarbunga volcano is located under NW part of the Vatnajökull icecap. Vatnajökull is the largest glacier in Europe. Veidivötn and
Trollagigar are related fissure systems, which extend about 100 km SW. It has been one of the most active volcanoes in Iceland the past few hundred years.
A fissure eruption at Thjorsarhraun produced the largest holocene lava flow on earth with a volume of 21 cu km. The 1477 eruption of Bardarbunga was large with a volcanic explosivity index of 5.
2014 Earthquake swarm
An earthquake swarm began under Bárdarbunga volcano, Iceland on 16th August 2014.
2010 Earthquake swarm
An earthquake swarm began at Bardarbunga volcano on 26th September 2010.
Henning Andersen
vulkaneksperten.dk
Tlf. 38 – 193411 og 20-764247
Hennings nye bog: “Vulkanen Hekla – Islands dronning udkommer i november 2014 på Mellemgaards Forlag.
