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 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
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.
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
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)
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
See live webcam from the area