Bardarbunga 2014

Udbrud fortsætter…

Bárðarbunga Volcanic System, a pre-publication extract from the Catalogue of Icelandic Volcanoes, to be made publically available in the coming months.

Web-cameras from M&T ehf are watching the area in various directions.

Web-camera from Míla is watching Holuhraun where a small lava eruption took place. Please observe that Míla’s background photo has nothing to do with the current events.

1. September 2014

Bárðarbunga: 01.09.2014, 12:20 UTC

Scientists from the Icelandic Met Office and the Institute of Earth Sciences and representatives of the Civil Protection in Iceland attend the meetings of the Scientific Advisory Board of the Icelandic Civil Protection.

Conclusions of the Scientific Advisory Board of the Icelandic Civil Protection:

· The lava eruption on Holuhraun continues. Lava flows northward from the eruption site.

· At 13:00 UTC today, an overflight will be made over Holuhraun and north-west Vatnajökull with scientists from the Icelandic Meteorological Office and the University of Iceland, together with a representative from the Icelandic Civil Protection. Observations from this flight will be reported in later briefings.

· At 20:00 UTC yesterday, the lava extended over a 3-km-area. This corresponds to a magma discharge of 300 to 500 cubic metres per second. From observations yesterday evening, the volume of erupted lava is between 16 and 25 million cubic metres.

· The eruption has not created any ash-fall.

· Gas and steam rises to a couple of hundred metres above the eruption site, extending up to 1,200 m downwind.

· In connection with the FUTUREVOLC project, a gas monitoring station has been set-up near to the eruption site. Gas measurements indicate a high level of sulphur dioxide. People could be exposed to highly dangerous gas levels close to the eruption. It is essential that those visiting the eruption site are equipped with gas sensors and gas masks.

· According to the latest GPS observations, horizontal ground movements continue in response to the dyke intrusion. There is no clear sign of a pressure decrease in the dyke intrusion in connection with the ongoing eruption, although there are irregularities in GPS displacements at nearby stations. The northern extent of the dyke intrusion has not changed to any great extent.

· When Sunday’s eruption began earthquake activity decreased somewhat, although seismicity remains high, with over 500 earthquakes detected since midnight today. Most of the seismicity is occurring on the northern end of the dyke intrusion, covering a 15-km-long region that extends partly beneath Dyngjujökull and north of the ice margin.

· At 08:58 UTC today, a magnitude 5.0 earthquake was recorded on the Bárðarbunga caldera, and another of magnitude 5.2 at 11:41 UTC in the same region.

· It remains unclear how the situation will develop. Four scenarios are still considered most likely:

o The migration of magma could stop, resulting in a gradual reduction in seismic activity and no further eruptions.

o The dike could reach the Earth’s surface causing another eruption, possibly on a new fissure. Lava flow and (or) explosive activity cannot be excluded.

o The intrusion reaches the surface and another eruption occurs where either the fissure is partly or entirely beneath Dyngjujökull. This would most likely produce a flood in Jökulsá á Fjöllum and perhaps explosive, ash-producing activity.

o An eruption in Bárðarbunga. The eruption could cause an outburst flood and possibly an explosive, ash-producing activity. In the event of a subglacial eruption, it is most likely that flooding would affect Jökulsá á Fjöllum. However it is not possible to exclude the following flood paths: Skjálfandafljót, Kaldakvísl, Skaftá and Grímsvötn.

· Other scenarios cannot be excluded.

From the Icelandic Met Office:

The Aviation Colour Code for Bárðarbunga remains at ‘orange’ and the code for Askja at ‘yellow’.

1st September 2014 06:50 – from geoscientist on duty in the Icelandic Met Office

The activity around Bárðarbunga from midnight 1. September until 06:50: Volcanic activity in Holuhraun:

The fissure eruption is continuing at a stable level. No explosive activity is observed, the eruption remains an effusive lava eruption. Visual observation by webcam and low level volcanic tremor on seismometers do not show any obvious changes since evening. More detailled information will soon follow from scientists in the field. Seismic activity:

Around 250 earthquakes have been automatically detected until now. Most of them are located in the northern part of the magma intrusion, between the eruption site and south to about 10 km into Dynjujökull. Strongest events were up to around magnitude 2. The rate of events has decreased as a result of pressure release due to the eruption, but there is still ongoing continuous seismicity.

Several events have occurred around the Bárðarbunga caldera rim, strongest events were M4.2 at 03:09 on the southern rim and M4.5 at 04:59 on the northern rim. See maps.

In the broader Askja region, most events were located at Herðubreiðartögl, the strongest event there was M2.9 at 02:56. This area is a quite common place for seismic activity, the activity now is not necessarily caused by increased stress due to the intrusion (the tip of the intrusion is about 25 km SW of this cluster). Askja volcano itself was seismically quiet last night.

Photo: Sveinbjörn Steinþórsson – 31. August 2014 at 22:01

Udbrud i Island startet påny…

Tidligt i morges begyndte et nyt udbrud af glødende lavafontæner, der som springvand står op af sprækkerne i lavamarken. Vulkanaktiviteten sker fra det underjordiske spaltesystem, som tilhører vulkanen Bardarbunga under Vatnajøkull. Udbruddet finder sted udenfor gletscheren og skaber herved ikke så kraftig askeudvikling. Med andre ord: “Overtrykket er ved at gå af vulkanens ophobede magmamængde i undergrunden.

A new eruption in Holuhraun has started

31st August 2014 08:40 – Eruption in Holuhraun observed 05:15

Observation from scientists in the field (05:15): It appears that the eruptive fissure is longer than in the last eruption. It is extending north and south on the same fissure. The eruption is a very calm lava eruption and can hardly be seen on seismometers (almost no gosórói). Visual observation confirm it is calm, but continuous.

Observation from scientists in the field (07:15): It appears that the eruptive fissure is longer than in the last eruption. It is extending north and south on the same fissure. The eruption is a very calm lava eruption and can hardly be seen on seismometers (almost no gosórói). Visual observation confirm it is calm, but continuous.

IMO has chnged the aviation colour code of Bárðarbunga to “red”.

Photo taken by: Ármann Höskuldsson

Nyt fra Island…

Chemical composition of the basalt erupted on 29. August, 2014 through the 1797AD Holuhraun linear vent system, North Iceland

The basalt erupted on 29. August, 2014 through the 1797AD Holuhraun linear vent system, North Iceland

Rock texture – basic observations:

The basalt is vesicular and with about 2 volume % (vol.%) ofvisible plagioclase crystals, reaching up to 3 mm in diameter along with trace amount of clinopyroxene and olivine crystals. The groundmass is dominantly composed of brown silicate glass, but microlites of colorless and elongated plagioclase, short prismatic clinopyroxenes and olivinesare presentas well (see photomicrograph). These crystals are randomly oriented and make up about 20-25 vol.% of the rock. Sulfide blebs are present in trace amount (<1 vol%).Element concentration maps produced by scanning electron microscopy show that the sulfide blebs are Cu-Fe-sulfides containing minor amounts of Ni.

Interpretation:

The high vesicularity of the basalt indicates degassing at shallow depth in the conduit and at the surface. Loss ofvolatiles (mainly H2O)raises theliquidus (i.e. melting) temperature of the silicate melt, which promotes enhanced crystal nucleation without drop in temperature and results indegasing-induced crystallization of microlites. This abundance of microlitesexplains the relatively high viscosity of the basaltic a’a lavaformed by the 29 August 2014 event.

The minor amount of sulfide blebs in the lava is noteworthy, because their presence indicates considerable sulfur-content of the melt.However, it appears that most of the sulfur from the basalt however was not released to the atmosphere during the eruption but remained trapped in the rock.

Courtesy of the Petrology Group of the Faculty and Institute of Earth Sciences.

Photomicrograph of the basalt erupted 29 August 2014 on the flood plain north of Dyngjujökull, North Iceland.

The basalt is highly vesicular and comprised of brown glass and microlites of plagioclase feldspar, clinopyroxene (augite)

and olivine. Sulfide blebs are also present. The relative amount of crystalline phases is plagioclase>>clinopyroxene>olivine>>sulfide.

Picture a, b, c were taken in plane polarized light, picture d by reflected light.

X-ray maps of Holuhraun basalt produced by scanning electron microscopy. Greater brightness indicates high concentrations and darker shades indicate low concentration for the analysed elements. Cu- and Fe-maps were made on the sulfide-rich segment indicated by the white box on the S-elemental image.

Major-element composition of lava erupted 29 August 2014 north of Dyngjujökull

Preliminary analysis of the lava yield a composition close to that of the Holuhraun lavaflow field directly beneath the new lava (Table 1). Slight differences are, however, seen in the concentrations of aluminium and titanium oxides. These major element analyses show that relatively primitive (>7 % MgO) basalts were produced by this small fissure eruption. The outstanding question whether the magma is coming from the Bárðarbunga volcanic system (which hithereto has been the loci of the ongoing seismicity and crustal deformation) or the nearby Askja volcanic system (which is experiencing increase in seismic activity) cannot be answered by the major element data alone (Table 1). Precise analysis of trace element concentrations and isotope ratios are required to resolve this important concern.

Table 1
	SiO2	TiO2	Al2O3	FeO*	MnO	MgO	CaO	Na2O	K2O	P2O5	Sum
Bárðarbunga volcanicsystem basalt, 6-8wt% MgO; average of 95 wholerock analyses	49.64	1.85	14.43	11.88	0.20	6.86	11.93	2.25	0.24	0.23	99.49
Standard deviation	0.74	0.44	1.59	1.55	0.03	0.55	0.94	0.25	0.09	0.08	0.51

	SiO2	TiO2	Al2O3	FeO*	MnO	MgO	CaO	Na2O	K2O	P2O5	Sum
Askja volcanicsystem basalt, 6-8wt% MgO; average of 145 wholerock analyses	49.63	1.71	14.18	12.07	0.21	6.84	11.54	2.16	0.29	0.17	98.80
Standard deviation	0.55	0.16	0.65	0.74	0.01	0.38	0.61	0.14	0.06	0.02	0.60

	SiO2	TiO2	Al2O3	FeO*	MnO	MgO	CaO	Na2O	K2O	P2O5	Sum
Holuhraun ; average of 5 wholerock analyses (Hartley and Thordarson 2012)	49.51	1.68	14.26	11.93	0.21	7.13	11.92	2.14	0.20	0.16	99.13
	0.30	0.03	0.14	0.14	0.00	0.09	0.04	0.05	0.01	0.01	0.48

	SiO2	TiO2	Al2O3	FeO*	MnO	MgO	CaO	Na2O	K2O	P2O5	Sum
Sample PKT77a collected 29 August 2014; average of 6 wholerock analyses	50.72	1.78	12.94	12.37	0.21	7.06	11.93	2.40	0.20	0.25	99.87
	0.21	0.02	0.09	0.06	0.01	0.10	0.12	0.06	0.01	0.01	0.01

Courtesy of the Petrology Group of the Faculty and Institute of Earth Sciences.

Bardarbunga seneste nyt fra BBC og Island.

Copyright: BBC News

Iceland’s volcano ash alert lifted

Bardarbunga is part of a large volcano system hidden beneath the Vatnajokull ice cap in central Iceland

An eruption near Iceland’s Bardarbunga volcano that briefly threatened flights has ended, local officials say.

The fissure eruption at the Holuhraun lava field north of the Vatnajokull glacier stopped at 04:00 GMT on Friday.

Before lifting air travel curbs, the Icelandic Met Office (IMO) lowered its aviation warning from red to orange – the second-highest level.

Iceland’s Eyjafjallajokull volcano erupted in 2010, producing ash that disrupted air travel across Europe.

The IMO said the eruption had started just after 00:00 GMT on Friday and lasted about four hours.

The fissure eruption took place between Dyngjujokull Glacier and the Askja caldera, according to a statement from the Department of Civil Protection.

Steam rises over a 1-km-long fissure in a lava field north of the Vatnajokull glacier, which covers part of Bardarbunga volcano system - 29 August 2014

No ash has been detected in the eruption but steam has been rising from the volcano

Steam and smoke rise over a 1-km-long fissure in a lava field north of the Vatnajokull glacier, which covers part of Bardarbunga volcano system

Officials say all airports are functioning normally

Earlier, Bjorn Oddsson, a geophysicist from Iceland’s Department of Civil Protection and Emergency Management, said the eruption had not affected air travel.

“It’s mostly effusive; there’s no ash in the air, and not even in the vicinity,” he said.

“So mostly lava is pouring out of the craters right now and the only flight restriction is over the area. All airports are open, and things are quite in control.”

BBC transport correspondent Richard Westcott says that even if a big cloud of volcanic ash were emitted, it would not cause the same level of disruption to flights that brought Europe to a halt in 2010.

He says new equipment that airliners and engine makers have been testing would allow planes to identity and fly around ash clouds.

Henning Andersen

vulkaneksperten.dk

Tlf: 20-764247