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Volcanic system: Bárðarbunga system of Iceland

30/08/2014 | By | Reply More

The Bárðarbunga volcanic system has been highly active in the Holocene with at least 26 eruptions in the last 11 centuries.

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A view of the Askja caldera to the south. Kverkfjöll and Dyngjujökull with rivers of Jökulsá á Fjöllum visible in the distance. Photo by GVA, Fréttablaðið

The last eruption took place in 1910 CE. The Bárðarbunga system lies on the Eastern Volcanic Zone and is about 190 km long and up to 25 km wide, consisting of a central volcano rising to 2009 m a.s.l. and a fissure swarm partly covered by the Vatnajökull ice cap.

The central volcano has an 80 km2 ice-filled caldera. The characteristic activity is explosive basaltic eruptions occurring on central volcano flanks or the fissure swarm. Known eruptions have mostly been VEI 3-4 but occasionally VEI 5-6 (bulk volume of tephra up to 10 km3). The largest eruptions occurred in the early Holocene, effusive basaltic eruptions on the fissure swarm with lava volumes ≥20 km3. Eruption frequency during the last 1100 years is 1 eruption per 50 years on average. Eruptions on the ice covered part of the system have the potential to cause major floods in several rivers flowing southwards and northwards from the Vatnajökull ice cap.

Follow­ing the seismic acti­vity in nort­hwestern Vatna­jök­ull the Icelandic Meteorological Office has recei­ved permissi­on to reveal the chap­ter Bárðarbunga Volcanic System, from a lar­ger assess­ment that will soon be pu­blis­hed on all of Iceland’s volcanoes. The secti­on is compi­led by Guðrún Lar­sen and Magnús T. Guðmunds­son of the Institu­te of Earth Sciences, Uni­versity of Ice­land. The follow­ing is a short prec­is from the orig­inal docu­ment crea­ted by Guðrún and Magnús.

26 erupti­ons in 11 cent­uries

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Aviation color codes for Iceland’s volcanoes. Bárðarbunga is in orange, indicating “increased potential for eruption.” The rest are in green, indicating a background state – source: The Icelandic Meteorological Office

In the chap­ter it says that the Bárðarbunga volcanic system has been highly acti­ve in the Holocene with at le­ast 26 erupti­ons in the last 11 cent­uries.

The last erupti­on took place in 1910 CE.

The lar­gest erupti­ons occur­red in the ear­ly Holocene, effusi­ve basaltic erupti­ons on the fissure sw­arm with lava volu­mes ≥20 km3. Erupti­on frequ­ency dur­ing the last 1100 ye­ars is 1 erupti­on per 50 ye­ars on avera­ge.

It is stated that erupti­ons on the ice co­v­ered part of the system have the potential to cause maj­or floods in sever­al ri­vers flow­ing sout­hw­ards and nort­hw­ards from the Vatna­jök­ull ice cap.

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Present and former rift zones of Iceland. 1v: Western Rift Zone (WRZ); 1n: Northern Rift Zone (NRZ); 2: former Snæfellsnes-Skagi Rift Zone (SRZ); 3: former Westfjords Rift Zone (WRZ); 4: Eastern Volcanic Zone (EVZ) – most likely a future rift zone. – Author Snaebjorn

Ice co­v­ered central volcanoes

Both Bárðarbunga central volcano and Ham­ar­inn, a potential second central volcano loca­ted 20 km SW of Bárðarbunga, have extensi­ve ice co­ver. The 2009 m high Bárðarbunga central volcano lies at the NW edge of Vatna­jök­ull ice cap, with only its NW slopes ice free.

It is dom­ina­ted by a 80 km2 and up to 700 m deep ice-fil­led caldera.

The Holocene erupti­on history is not fully known, but lava flows and tephra deposits from erupti­ons on the ice free parts of the fissure sw­arm have been mapp­ed in some detail.

Phreatomag­matic basaltic erupti­ons are the dom­in­ant type for the ice co­v­ered part of the volcanic system with the num­ber of verified erupti­ons in the last 1000 ye­ars being 22. However, only one erupti­on out of every four left a tephra layer in the soils outsi­de the Vatna­jök­ull ice.

Effusi­ve basaltic erupti­ons on ice-free part

Effusi­ve basaltic erupti­ons on the fissure sw­arm are the dom­in­ant type for the ice-free part of the fissure sw­arm. At le­ast 22 erupti­ons have been verified on the fissure sw­arm SW of Vatna­jök­ull in the last 9000 ye­ars.

Despite the avera­ge of 2 erupti­ons per cent­ury dur­ing the last 1000 ye­ars, most of the erupti­ons occur­red in the in­terval 1200-1500 CE and in the 18th cent­ury. The durati­on of these exp­losi­ve erupti­on ranges from days to months.

Possi­ble scen­ari­os based on the history

In the chap­ter on Bárðarbunga possi­ble erupti­on scen­ari­os are based on known events in historical times (last 1100 ye­ars). However in­formati­on on the cur­rent acti­vity can be found on the Icelandic Meteorological Office website.

Small erupti­ons (<0.1 km3)

A small exp­losi­ve erupti­on below NW Vatna­jök­ull may last for days or weeks, e.g. the 1797 CE erupti­on. Length of warn­ing per­i­od is unknown. Likely magma compositi­on is basaltic. Peak acti­vity will not necess­arily occ­ur at the beg­inn­ing of the erupti­on. Acti­vity is expected to be in­termittent. In­ten­se tephra fall outsi­de Vatna­jök­ull is possi­ble.

Modera­te erupti­ons (0.1-0.5 km3).

A modera­te exp­losi­ve erupti­on below NW Vatna­jök­ull can last for weeks to months, as the 1717 CE erupti­on that lasted from ear­ly Aug­ust to mid-Sept­em­ber 1717, sprea­ding tephra across North and Nort­heast Ice­land. Length of warn­ing per­i­od is unknown.

Erupti­on col­umn heig­ht unknown but could exceed 14 km. In­termittent but su­bst­antial tephra fall and dark­ness in prox­imal areas (<40km) can be expected (Figure 5a). Tephra fall could reach main­land Europe. A predom­in­antly effusi­ve erupti­on on the fissure sw­arm can last in­termittently for 1-2 ye­ars, such as the 1862-1864 CE Trölla­hraun fires, that produced 0.3 km3 of lava on a 16 km long fissure.

Could cont­inue for months to ye­ars

Lar­ge erupti­ons (>0.5 km3) including lar­gest likely erupti­on.

In the last 1100 ye­ars the lar­ge erupti­ons have been con­fined to the fissure sw­arm sout­hwest and north of Vatna­jök­ull. No lar­ge erupti­ons are known to have occur­red in the central volcano. A lar­ge fissure erupti­on is likely to cont­inue for sever­al months to ye­ars. Warn­ing per­i­od is unknown. Instrumental precursors are expected to be seen before erupti­on out­break. A discont­inu­ous volcanic fissure over 60 km long between the extreme ends can be expected. Depend­ing on the locati­on of the fissure, it could be eit­her predom­in­antly exp­losi­ve, or predom­in­antly effusi­ve.

Volcanic eruption confirmed on August 29. 2014 north of Dyngjujökull

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From the volcanic eruption in Holuhraun, Iceland on August 29. 2014 – Photo by Vilhelm Gunnarsson

Lava eruption has begun in the Holuhraun lava field, north of Dyngjujökull. The Icelandic Meteorological Office confirms that and webcams in the area show that lava is braking its way up on the surface.

First news from the Civil Protection in Iceland tell us that the Lava is making its way up on the surface in a 400m long area north of Dyngjujökull.

The eruption is located on an ice-free zone which tells us that no ice is being melted so far causing floods in rivers in the north of Iceland. “This is probably located on the north end of the lava tunnel that moves from under Dyngjujökull. The eruption is located on an ice-free zone” says Rögnvaldur Ólafsson from the Civil protection in Iceland.

“The eruption is not a big one, but we urge people to be safe and not go to near the eruption,” says Rögnvaldur. “There are chances of explosions.”

Watch below, the first video of this newest eruption of Iceland (source: RUV)

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Specialists at the Icelandic Meteorological Office and the University of Iceland will met today to discuss the short lived eruption and what might possibly follow. At this moment it is unclear how the situation will develop.

Update August 30. 2014 at 18:00 pm GMT

Scient­ists from the Icelandic Meteorological Office, the Institu­te of Earth Science and representati­ves from the Civil Protecti­on Depart­ment met this morn­ing to go over the situati­on in the area around Bárðarbunga, Dyngju­jök­ull and Holu­hraun.

The key po­ints of their meet­ing are:

  • Seismicity remains high with over 700 qua­kes since midnig­ht, coun­ted at 11:45 GMT.
  • The most powerf­ul eart­hqua­kes in the area since midnig­ht were a magnitu­de 4,5 qua­ke in nort­hern Bárðarbunga around 02:35, a magnitu­de 4,2 eart­hqua­ke in the same area at 06:18 and 5,4 magnitu­de eart­hqua­ke at 07:03 on the sout­hern edge of Bárðarbunga. All times are GMT.
  • Around 20 eart­hqua­kes have hit around Askja. Out­flow of magma into the dyke could explain these tremors.
  • Jök­ulsá á Fjöll­um, as well as ot­her ri­vers north of Vatna­jök­ull show no signs of change in water flow.
  • Scient­ists are exam­in­ing the fresh lava from Holu­hraun.

Cur­rently, th­ere is no way of tell­ing what will happ­en. Four likely scen­ari­os are gi­ven:

  • In­flow of magma into the dyke from Bárðarbunga will stop, resulting in the event slowly fading out with no fur­t­her erupti­ons.
  • The dyke will again break through to the surface north of Dyngju­jök­ull, possi­bly in a dif­f­erent area than last time but not und­er Dyngju­jök­ull.
  • The dyke mig­ht break through und­er Dyngju­jök­ull, resulting in a jök­ul­hlaup and significant ash fallout.
  • An erupti­on in Bárðarbunga, resulting in a jök­ul­hlaup in Jök­ulsá á Fjöll­um, but also possi­bly in Skjálf­andafljót, Kalda­kvísl, Skaft­ár­katl­ar and Grím­svötn.

Ot­her scen­ari­os are also possi­ble.

The aviati­on code over Bárðarbunga remains orange and yellow over Askja.

Update August 31. 2014 at 06:50 am GMT

A New fissure eruption has started in the Holuhraun lavafield this early Sunday morning, ca. 9 kilometers north of Dyngjujökull glacier, scientist confirm.

The eruption seems to have started near the northern end of the magma intrusion that has been propagating northward from the Bárðarbunga caldera since August 16.

The Icelandic Meteorological Office has issued a red alert for aviation, restricting flight around the eruption site.

Watch video from RUV (The Icelandic National Broadcasting Service) of a stunning new lava forming in Holuhraun

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See live webcam from the area

Bárðarbunga: Webcam 1
Bárðarbunga: Webcam 2

 

 

Category: Iceland

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