Discover the World: Education Geographical Association

Regular Updates: Iceland Volcanic Activity

We will update this page when any further significant changes develop.

Fissure Eruption Update
Experts at Discover The World and Ari Trausti Guðmundsson 20/11/2014

Twelve weeks have passed since the volcanic activity began at the Holuhraun eruption and the lava flow rate is showing no sign of diminishing. The oblong and steep crater hill still has at least three powerful lava vents filling the boiling lava pond, the lava sheet continues to grow at a steady rate. The total area of the lava flow now exceeds 74km² making this the largest lava-producing event in Iceland since the Laki Fires in 1783-4.

The map below, issued by the Geoscience Institute, dates from 14th November and demonstrates the size of the affected land. Judging by the activity in the past few weeks, it is likely that the eruption will last for many more months or even years.

ari article image

The eruption continues to release high levels of sulphur dioxide but with limited impact on the Icelandic population. Tourism has remained unaffected by the activity although many hope to catch a glimpse of the eruption.

The earthquake activity is retained in the Bardarbunga volcano, although somewhat less powerfully than of recent weeks. In the last few days, the frequency of earthquakes has been constant but no earthquakes have reached a magnitude of 5. The prime location of the seismic activity is at the northern / north-eastern rim and below the outer slopes in the north.

No trembling has occurred in the long stretch around the upper part of the big magma dyke (where the presumed connection between the magma chamber and the dyke is situated). A dozen or so small ‘dyke-quakes’ have occurred daily lower down below the Dyngjujokull outlet glacier and in Holuhraun. Localised warming-up of the caldera is evident from a few new ice cauldrons along the caldera rims. However, there are no signs of any eruption activity underneath the deepening ice depression in the ice dome of Bardarbunga.

heat photo

Heat photo of the Holuhraun crater – vedur.is

 

Fissure Eruption Update
Experts at Discover The World and Ari Trausti Guðmundsson 26/10/2014

The lava emission from the large (threefold) crater at Holuhraun continues with no evident signs of a decline in the lava extrusion. The lava flow now covers an area of around 62km²: the proposed name for the crater is Baugur (Circle) and for the lava flow is Nornahraun (Witches Lava).

The map from the Geoscience Institute is valid for 23rd October, 2014.

The second map from the Met Office (by Emmanuel Pagneux and Tinna Thordardottir, Oct. 8th), shows the estimated travel times for a flood in the wake of a possible subglacial eruption in the catchment area of the Dyngjujokull outlet glacier. The map does not show a probable eruption site but is based on a discharge at the glacier edge of 25,000m3/s and a constant flood velocity of 5m/s.

Any likely flood would travel onward along the upper river bed of Jokulsa a Fjollum, into the canyon of Jokulsargljufur and then across some flat areas in the Kelduhverfi district (not shown on this map) before reaching the fjord bay of Oxarfjordur.

Temporary evaluations like this are made in order to be better able to decide upon the counter-measures, as well as to formulate evacuation plans; something that institutions like the Road Authority, Civil Protection and Landsnet and Rarik electrical transmission companies have been addressing. The areas in question are away from where most school groups are travelling. Areas at immediate risk are already restricted and should be of little or no concern to tourists who follow the guidelines such our by the emergency services.

The flooded area at the new lava partly explains why the access is restricted. Furthermore, high-level seismic activity is still registered at the Bardabunga volcano with frequent quakes of magnitude over 4 and 5, especially at the northern caldera rim as well as beyond that, at the northern/northwestern slopes of the glaciated volcano.

bardbunga-update-map1-261014

bardarbunga-update-map2-261014


Fissure Eruption
Experts at Discover The World and Ari Trausti Guðmundsson 19/10/2014

The lava outpouring from the short fissure at Holuhraun has now remained steady for weeks. Three interconnected vents (300-400 m long) are what remains of the original 1.9-km-long, once active fissure. The height of the crater hill around the vents exceeds 100 m, taking the form of a lava shield (also known as a shield volcano) - see the image from the Geoscience institute by geoscientist Morten Riishuus.  The big regional dyke is still going strong and the eruption could remain active for many years or die down within a few weeks or months. Further breaching of the surface along the dyke leading to a subglacial eruption in the Dyngjujökull outlet glacier is still possible.

The lava flow now has an area of roughly 60km² and a volume of approximately 800 million cubic metres (0.8 cu. km). The Hekla lava flow is somewhat similar in size but was generated in 13 months. Therefore, the highlands will soon become the largest lava flow occurring within such a short interval in Iceland - since the late 18th century. New trace elements and isotope analysis are said to indicate a magma source at a depth of at least 15 km. 

The included map is from the Geoscience Institute and the Coast Guard (October 17th).

The Bárðarbunga central volcano continues to shudder, with dozens of earthquakes every day. On October 18th, two earthquakes were recorded with a magnitude 4.7 and 5.0, with a further two on the 19th with a magnitude of 5.2 and 4.5. Currently, the depression in the caldera ice dome is over 35 m deep. The main earthquake location is at the northern rim of the caldera or at the volcano flank in the north. GPS-readings over a period of a few days show both dilation and/or doming of the volcano. Reverse faulting has been detected from some earthquakes. Another earthquake location is at the south-eastern rim. Practically no earthquakes originate in the caldera floor. With time, a simple model of caldera floor subsidence and a direct link between a Bárðarbunga magma chamber and the big dyke seems more and more unlikely.

I have stressed before, as have prof. Águst Guðmundsson (Royal Holloway – University of London) and prof. Þorvaldur Þórðarson (University of Iceland) in talks and in an article (in the Bulletin of Volcanology), that a large magma reservoir, is the possible site of the magma influx into the dyke. Independently of this, the roots and the non-verified (but naturally alleged), shallow magma chamber remains beneath the caldera, a theory consistent with chemical signals in the magma. The magma from a deeper reservoir is probably being injected into the volcano, even as ring dykes. It remains to be seen if this hypothesis is correct but many indications are present.

There is no way to predict what will happen at Bárðarbunga; small or large eruptions may occur, and similar tectonic movements or a sudden caldera collapse could become the result of the processes in the volcano.

The many scenarios presented by the Civil Protection and its Scientific council are still valid. The nearby Tungnafellsjökull central volcano (with a caldera), west of Bárðarbunga, has been the site of over 150 earthquakes (with the majority of them with magnitude less than 3.0). Most of them have loci at shallow depth but some originate much deeper, at up to 20 km plus. This probably indicates an influx of magma but the GPS-readings do not support that, so far. Magma intrusions in a volcano do not automatically lead to eruptions.

It is interesting to note that the Kverkfjöll central volcano (with two calderas), the next neighbour of Bárðarbunga in the east is showing very little tectonic activity. Only a few dozen quakes have originated there and the same story can be said about the very active Grímsvötn central volcano southeast of Bárðarbunga. It is, at any rate, important to follow the development of all nearby volcanoes with care.

More elaborate seismic and GPS monitoring would help in revealing the processes at hand below the earth´s surface in this very active part of Iceland.

DG 20th 1

Compiled by: Geoscience Institute of the University of Iceland/Coast Guard
Map base: The Geodetic Survey.

DG20th2

Photo: Morten Riishuus, Geoscience Institute
Dates: 28th Sep and 15th Oct

 
Fissure Eruption Update
Experts at Discover The World and Ari Trausti Guðmundsson 05/10/2014

 The volcanic unrest and vigorous earthquake activity that began on August 16th has now surpassed seven weeks.

 Over 25,000 earthquakes have been registered including 40 above a magnitude of 5, four volcanic eruptions have also occurred. A common annual number of earthquakes in Iceland is estimated at 10,000-15,000.

 The current eruption (starting at the end of August) is now concentrated in a short section of the original fissure where three vents within one elongated crater (named Baugur) spout lava. The discharge is estimated between 50-100 cubic metres per second and the lava fountain activity is rather low. The lava flow has an area of 48 square kilometres (18 sq. miles), roughly the same as Exeter. Its average thickness is 14 m and the volume 670 million cubic metres or 0.67 cubic kilometres. The eruption now ranks amongst the highly productive eruptions in Iceland. If it continues for a long time, a lava shield will be piled up around the vents which will develop into a large summit crater.

The land covered by new lava is solely condensed to an area of old lava flow, sand plains and river tributary beds, devoid of vegetation. There is still ample room for a growing flow and courses of rivers could be altered, damming of rivers is possible and new waterfalls could form. 

The heavy earthquake activity at the Bárðarbunga central volcano continues, as does the subsidence of central parts of the ice dome that covers it. The shallow bowl is about 30 m deep and the downward movement of the glacier ice has been interpreted as a sign of caldera floor subsidence.

It is not possible to forecast the development of this highly interesting unrest. Only time will tell.

The map of the lava flow is dated Sept. 30th. It is compiled from various sources and published on the web-page of the Geoscience Institute (www.jardvis.hi.is)

DG Update

 

Fissure Eruption Update
Experts at Discover The World and Ari Trausti Guðmundsson 23/09/2014

The lava discharge in the Holuhraun craters lingers on with constant intensity. The flow area is now about 40 sq. km, which is a substantial figure for Iceland.

The volume depends on the average thickness figure used; 6m renders a total of 240million m³ of lava whilst 8m equates to 320million m³. As a comparison, the total volume of lava in the Krafla Fires (9 eruption 1975 to 1984) was around 250million m³, whilst Hekla emitted 800 to 900million m³ in 13 months (1947-1948).

Earthquakes close to the large dyke seem to concentrate to a subglacial location about 5km upstream from the glacier margin of Dyngjujokull. A subglacial, tephra-producing eruption is kept in the list of possible scenarios. In case, a flash flood would follow the course of the river Jokulsa a Fjollum. This is the checked preliminary data rendering from the SIL group at the Met. Office (at noon today). The map shows the activity for the past 13 hours.

bardarbunga-graphic-230914

 

Fissure Eruption Update

Experts at Discover The World and Ari Trausti Guðmundsson 20/09/2014

The eruption in Holuhraun is stabilised for the time being. Much of the lava (a rough estimate is somewhere near 50 cu.m/sec.) flows to the east/northeast of the crater which starts to look like and elongated, high hill. If the eruption continues in this way for months or even years, we would probably be looking at the formation of a lava shield, somewhat similar to the one in Surtsey.

The difference would be at Surtsey, the confined lava capped a high tephra cone from a largely submarine eruption. In Holuhraun, much of the lava would surround a gently sloping "mountain" with some kind of a summit crater with long lava tubes. There are many such structures on dry land in Iceland, but all are less than a few thousand years. However, the eruption might die down within days or weeks.

The shaking of Bárðarbunga also continues with similar intensity; the ice bowl in the top slowly deepens. The future of Bárðarbunga is still very much uncertain.

Chemical analysis and model calculations as well as 3D rendering of earthquake loci show that the magma in this series of unrest originates at a greater depth than 10 kilometres. This opens up interpretations of the mechanism at depth which is different to the one that states that the magma chamber in Bárðarbunga supplies the large dyke (and the Holuhraun eruption) with magma, largely through lateral magma flow.

 

Fissure Eruption Update

Experts at Discover The World and Ari Trausti Guðmundsson 15/09/2014

The lava eruption fissure in Holuhraun remains active along a small section, where the main crater (called Baugur) and two smaller ones continue to spout fluid lava. The fountain activity is concentrated in the main crater, over 100m in full vigour.

Lava flow has stopped extremely close to Vaðalda (see map below, compiled from various sources by the Icelandic Met Office/Geoscience Institution.) but continues to spread out closer to the craters. A formation of a lagoon behind a wall of lava is now out of scope, for the time being. The area is now well over 20km² and the volume estimated is at least 150 million cubic metres.

The high intensity of large earthquakes (>4,0) along the Bárðarbunga caldera rims remains and the subsidence of central parts of the ice dome continues with the "ice/snow bowl" now over 25m deep. This has been attributed to caldera floor subsidence. The whole mechanism and interaction between the big dyke, magma chamber, the present lava eruption, other dykes and further possible deeper reservoir sources of the magma are not clear.

The development from now could go a number of ways: The Holuhraun eruption could decline and activity cease in a few days; it could continue for weeks at a similar level or it could grow in strength with new, similar fissures opening up (also beneath the Dyngjujökull outlet glacier). It is also possible that volcanic activity starts in the Bárðarbunga caldera or at the outer flanks of the volcano. In that case, the eruption size is unpredictable; we could even witness a large eruption with glacial flooding (jökulhlaup).

The eruption has, as is always the case, altered the Holuhraun landscape. The fresh, black lava formed a long, somewhat high with a broad berm, about 20 km long.

The spatter and scoria craters range from a few metres to over 60m high forming a straight row with an older Holuhraun crater (late 18th century) at the southern end - where the Suðri lava ring is attached. The waterfall Skínandi in the river Svartá has escaped destruction.

 DG image

 

Fissure Eruption Update

Experts at Discover The World and Ari Trausti Guðmundsson 11/09/2014

The Holuhraun fissure is "alive and well" and there are currently a few changes to observe. The lava flow now covers well over 20 sq. km and has moved a further 1 km forward in a day. The highest magma fountains are well over 100m in height but from fewer vents than at first.

More shallow ice depressions have been found in the Dyngjujokull outlet glacier, all lined up above the dyke trajectory. They seem to be caused by small eruptions and / or tectonic subsidence.

The main area of interest focus on the Bárðarbunga caldera (see photo). The many large earthquakes, mostly along the caldera rims with three most frequented sites, continue to shake the volcano and recent quakes of magnitude 5.0 + cause further change to the current situation. A large, shallow depression in the ice dome above the caldera, more than 20 m deep, has been registered and it is predicted that further subsidence could occur. There are four most likely scenarios:

One, the caldera floor continues to sink as the dyke gulps the lava in Holuhraun. This could result in a larger volcanic eruption, either from a lava fissure or within the caldera.

Two, the magma injections into the ring fractures of the caldera. This expands the volcano and can also cause further caldera subsidence, cone sheet formations and similar volcanic activity.

Three, a subglacial eruption might produce large amounts of tephra plus a large flood (jokulhlaup) because the ice cover at Bárðarbunga is 600-800 m thick. However, we should not expect the same impact as the Eyjafjallajokull eruption

The possible flood paths number at least four: two to the north/northeast (Skjálfandaflói and Öxarfjörður) and two to the south/southwest (Grímsvötn caldera or the Kaldakvísl/Tungnaá/Þjórsá river basin). The direction and size is determined by the location, the eruption discharge and the ice thickness.

The effects of a flood or tephra fall are not predictable, however to provide some context, the areas impacted by flooding will be restricted to sparsely populated areas, away from tourist areas or large settlements. Glacial bursts (jokulhlaups) are common in Iceland and the well-rehearsed emergency services have restricted access to areas of risk.

Four, the caldera subsidence could halt and the Holuhraun eruption could end.

 

 Photo: Oddur Sigurðsson - Met. Office.

 

Fissure Eruption Update

Experts at Discover The World and Ari Trausti Guðmundsson 08/09/2014

The earthquake activity is declining - Since 08:00am this morning only 2 - 5 quakes have been registered per hour. The low frequency eruption tremor is declining very slowly. The second small fissure has not erupted since yesterday and the older one has been spouting from isolated vents only with some 100 cu. m. per second. The lava flow continues to flow to the North East. The rumbling of Bárðarbunga continues and there are still four scenarios at hand:

- The activity may wither away
- Lava eruptions continue and new fissures open up in ice- free areas
- A sub glacial eruption starts in Dyngjujökull
- The unrest in Bárðarbunga itself leads to an eruption.


Fissure Eruption Update

Experts at Discover The World and Ari Trausti Guðmundsson 07/09/2014

The activity in the main volcanic fissure is concentrated into three main crater hills and the lava flow has now reached the river Jökulsá á Fjöllum starting to divert it. The lava area is now well over 16 sq. km (late afternoon 6th of Sept. - see the Geo science Inst. map) and is now producing more lava than the eruption in Askja in 1961, after five weeks (11 sq. km). The spouting fissure closer to the Dyngjujökull outlet glacier has almost ceased its activity and the lava flow is small. A sub glacial eruption has not been noted visually.

The earthquake activity at Bárðarbunga is still very strong (a 5.5-quake this morning). The interpretation of what is happening in and around the caldera below the 800-m-thick ice has been favored as a simple sinking-in of the caldera floor (see the other GI map). Other scenarios are still possible along with the explanation of the size of the big dyke in relation to the estimated outflow of magma from the magma chamber beneath the caldera (if the subsidence is upheld as the main process). A large regional dyke from a deep-seated magma reservoir can cause eruptions far away from a central volcano that has an associated smaller magma chamber in place, and activate this magma chamber at the same time (this scenario was experienced in the Laki eruption in 1783 – although I am not postulating that we are heading for a similar event)

The dozens of large earthquakes that have shaken a large central volcano (such as Bárðarbunga) for this long period, is a process we have not had the opportunity to study before. Is there an eruption in brewing? Has some magma already surfaced? Or is the tectonic deformation of Bárðarbunga caused by a combination of stresses from the big dyke as well as dyke formation (preferably ring dykes) at depth under the caldera?

As some of the earthquakes seem to denote uplift, how does that fit into the possible scenarios?

What an exciting series of events to follow!

 

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Fissure Eruption Update

Experts at Discover The World and Ari Trausti Guðmundsson 05/09/2014

The main fissure eruption seems to be proceeding with more or less constant vigour and the included map from the Icelandic Met. Office/Geoscience Inst./Civil Defence team shows the extension of the lava flow. Tomorrow it will most likely collide with one of the Jökulsá tributaries. Explosive action and steam release is likely to occur but it is possible that the lava will divert the river instead of damming it. The total lava volume is in excess of 50 million cu. m with a length of over 10 km and an area of 12 sq. km.

The smaller fissure eruption is still active but with much less lava discharge. Subsidence continues to occur underneath the glacier ice and the risk of an eruption there grows with each day (but not predicted with certainty).

A radar survey of the surface height of the ice dome above Bárðarbunga shows that the caldera floor must have subsided some 15 m during the series of earthquakes that have riddled the volcano (both due to in-sinking and shearing). The estimated volume that must have left the magma chamber is 0.25 cu. km, according to the scientist team. The volume of the big dyke, however, is in excess of 0.5 cu. km (a conservative estimation). The extra magma could originate in a deeper-lying magma reservoir that well-known models of volcanic system portray. The magma from the chamber may have participated in the formation of the big dyke but some of it did leave the chamber to form smaller dykes, e.g. in the west and during the small, sub glacial eruption on the southern slopes of Bárðarbunga.

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Fissure Eruption Update - Changes in the air?

Experts at Discover The World and Ari Trausti Guðmundsson 04/09/2014

 The free-air fissure eruption continues but with somewhat less vigor and since September 2nd, it is now concentrated to fewer and larger craters. The lava flow area is about 8 sq. km and some lava has met shallow river water. Small steam explosions have been noted and steam plumes have been expelled through crouching lava.The distance from the lava flow to the main tributaries of the river Jökulsá á Fjöllum is still considerable.

Yesterday, (September 3rd) the earthquake activity beneath the lower sections of the Dyngjujökull outlet glacier resumed. A large earthquake at Bárðarbunga seemed to resound in the lava fountain craters. This activity continues today and also at the northern end of the dyke. More earthquakes continue to be registered around Mt. Herðubreið, northeast of Askja.

A set of fissures and some subsidence along them have now formed a stretch 1km wide with a shallow section (containing the erupting fissure) which continues for many kilometers from underneath the Dyngjujökull ice towards Askja. It lies on top of the dyke and that is why the earthquake activity in Dyngjujökull has sparked talk of a possible sub glacial eruption which will potentially result in tephra-production and a flood. A volcanic eruption in Bárðarbunga is still not out of the question.

(Image taken Sept 2nd)

 

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Fissure Eruption Update

Experts at Discover The World and Ari Trausti Guðmundsson 03/09/2014

A helicopter flight and close inspection of the eruption site made evident that the main lava-fountaining and flow is in a 400-450m section of the original fissure.

The area of the lava flow increased by 1-2 sq. km between the afternoon of Sept. 1st and Sept 2nd. Today the activity is at a similar level as yesterday, but is more concentrated into fewer vents.

The earthquake activity around the northern part of the big dyke is substantial as well as northeast of the Askja volcano/caldera and the dyke. Some of the earthquakes have occurred under the lower section of the Dyngjujökull outlet glacier.

Large earthquakes (the last one 5.5) continue to occur in and around the Bárðarbunga caldera and seem in some cases to resound in the dyke activity. A volcanic eruption (tephra-producing) in Dyngjujökull or in Bárðarbunga is by no means ruled out.

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Fissure Eruption Update

Experts at Discover The World and Ari Trausti Guðmundsson 02/09/2014

During a flight with the Coast Guard 12:00 - 16:30 yesterday (1st September,) the northern part of the erupting fissure (7-800 m) was alive and well. A brown sandstorm (white plume up to 15,000 feet), bluish gas and the red fountains were an impressive sight, indeed. An estimate of the lava flow area has rendered more than 4km² and the mean lava discharge since that morning was approximately 100 cubic metres pr. sec.

The event could be roughly classified as a medium size lava-producing fissure eruption, much larger than the Fimmvörðuháls event 2010 and somewhat similar to the larger ones of the nine Krafla eruptions in 1975-1984.

Eye witnesses this morning (over the radio) tell that the eruption has somewhat grown in strength which low frequency tremors confirm. However, earthquake activity has reduced with 110 earthquakes registering between midnight and 07:00

An aerial image of the fissure eruption captured the morning of the 1st September.

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Fissure Eruption Update North of Dyngjujökull 

Experts at Discover The World and Ari Trausti Guðmundsson 01/09/2014

The newest lava-producing eruption is continuing. The discharge yesterday afternoon was estimated at 250-350 cu. m sec (like the largest rivers in Iceland) the lava is a thin, fast-flowing pahoe-hoe basalt lava. The environment is a mix of sand, gravel and older lava and the site is "well chosen" for such an event. 

Whilst there is no certainty it is possible that the eruption may last for a few days and slowly become concentrated in a part of the fissure, building the largest spatter and scoria craters.

The big dyke is still receiving a lot of magma. It is stationary and induces a lot of earthquakes both north and east of Askja. It is capable of continuing if stress conditions allow and it may "jump" to the side of its present bearing. If the present eruption stops soon, it is quite likely that more fissure eruptions will occur above the dyke, either in the ice-free area or beneath the Dyngjujökul ice.

The still forceful unrest and crustal movements in the Bárðarbunga volcano reminds us that there is still the possibility of a sub glacial eruption within the caldera or at the volcano slopes, however if a sub glacial eruption does occur we are not anticipating another Eyjafjallajokull style eruption

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Fissure Eruption North of Dyngjujökull 

Experts at Discover The World and Ari Trausti Guðmundsson 01/09/2014

Icelandic authorities have now lowered the aviation alert level from red to orange, due to an on-going fissure eruption north of Bárðarbunga volcano. The eruption started at 04:00 GMT Sunday. The eruption was similar to the first on the same fissure which erupted Friday however the active fissure is longer at 1.5km +

The eruption is located at Holuhraun, an ice-free lava field, around 4 km outside of the glacier which covers Bardarbunga. Bardarbunga is Iceland's largest volcano and one of the country's most hazardous. The recent activity is characterized by lava fountains and lava flows, and produces less ash than a sub glacial eruption.

Whilst the eruption could die down rather quickly it showed no signs of subsiding on Sunday afternoon. It is always possible that the fissure stretches or that the big dyke starts to emit magma elsewhere along its trace causing a more linear vent system to open up on the surface.

Adverse weather conditions have made it difficult for scientists to observe the eruption, however depending on visibility; they can be seen on a webcam located on a nearby mountain. The major chemical element analysis of a lava sample from the first eruption yields results that do not allow scientists to distinguish between it originating in the Bárðarbunga Volcanic System or the Askja Volcanic System. For that analysis trace elements and isotopes are required.

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Fissure Eruption North of Dyngjujökull - Ari Trausti Guðmundsson 29/08/2014

In the last 24 hours, a volcanic fissure has opened up in the lava fields north of Dyngjujökull, including some lava fountain activity. The eruption began at around midnight in the Holuhraun lava field 9 kilometers north of the Dyngjujökull outlet glacier with lava streaming out of a 100 meter long fissure.

Interest in the site began yesterday as Scientists detected small surface crevasses, open fissures and bedrock faults above the dyke, stretching about 5km in the ice-free area and for about 1km underneath the glacier. This happens because the depth to the crest of the dyke is narrowest here and the crust is relatively weak. Over 1,200 earthquakes were registered in the large dyke before the eruption began.

At this stage, there is no sign of volcanic ash activity and the Icelandic Met Office has reduced the aviation alert status from red to orange. 

More coming soon.

 

Bárðarbunga Volcanic Activity Update – Ari Trausti Guðmundsson 27/08/2014

The large earthquakes at the Bárðarbunga central volcano continue to occur. The most likely explanation is deformation and some caldera-floor subsidence due to the proximity of the large dyke.

The dyke pushes slowly forward in the direction of the Askja central volcano (and within its fissure swarm, as scientists have defined it) - at least 1-2 km per day. The earthquake activity is somewhat less pronounced but still strong. The depth to the magma on the move seems the same as before.

The dyke has begun to affect the stress field around Askja as noted from at least two sizeable earthquakes, one with a magnitude of 4.5. There is no way to predict whether the dyke is forcing its way into the roots and magma chamber of Askja (and even farther than that) or not, but such a scenario cannot be ruled out. Two other scenarios have been mentioned: The dyke dies down for good or until later - or a small or large lava eruption occurs on the stretch between Vatnajökull and Askja.

In 1874-1875 a series of basalt lava eruptions, chiefly north of Askja/Dyngjufjöll, and a plinian (strong), explosive tephra-production event in Askja occurred and had a serious affect on Iceland. The unrest has been attributed to the interaction of a basalt dyke injection into the central volcano and the associated fissure swarm. A somewhat similar incident is not predicted but is possible.

It is important to note that some media reports have been tagging what happened in the 19th century as "a mega eruption from a doomsday volcano", this is a gross exaggeration. The basalt lava flows were by no means large. The amount of silica-rich tephra, however, was rather large (2 cu. km as non-compacted material and about 0.4 cu. km as compacted rock - 400 million cu. m). The effects in modern times are hard to foresee.

The following map courtesy of the Met. Office shows recent earthquakes.

bardarbunga-graphic-270814


Bárðarbunga Volcanic Activity Update –
Ari Trausti Guðmundsson 25/08/2014

There was little activity at the site of the Bárðarbunga volcano today with the notable exception of an earthquake measuring 5.1 at 16:19; this happened at a few kilometres depth below the caldera rim and can be attributed to further deformation of the volcano (caused by the dyke activity to the east of it) and probably a sign of caldera floor subsidence. Whilst we cannot rule out further activity at the volcano itself, it is looking increasingly unlikely.

The main dyke continues to be more active, mainly in the region beyond the boundaries of the glacial ice cap (see Met Office map) - with about 1200 quakes since midnight, around 20 of magnitude between 3 and 4. It is still situated deep down in the crust (5-10km) although its tip is about 6-7km north of the ice cap boundary, and still creeping forward. It seems to have a deep source; possibly not the magma chamber underneath the caldera of Bárðarbunga, but a larger magma reservoir at a greater depth.

It is still probable we will see an eruption - maybe lava fountain-activity, some tephra (ash, pumice and scoria) and also a lava flow, given that a section of the dyke reaches the surface in an ice-free area. It is also possible that an event could include an eruption under the ice (subglacial) producing tephra as the magma interacts with the ice and snow.

Assessing the size or force of a possible eruption is pure guesswork. The scale could range from a small eruption to one of a size that we have not seen for many decades. We could also face a series of eruptions for years or even decades, something that is common in the volcanic history of the last millennium, illustrated for example by the Krafla Fires in NE-Iceland 1975-1984 (nine eruptions in nine years).

As in every report, I must stress that dyke activity could die down within a few days and either renew earthquake activity after a short or long interlude - or rest completely still.

bardarbunga-graphic-260814

MAP: From the Icelandic Met. Office website.


Bárðarbunga Volcanic Activity Update –
Ari Trausti Guðmundsson 24/08/2014

After some exciting hours yesterday and some controversy regarding a possible small subglacial eruption, the earthquake activity continues. The largest two quakes (4.9 and 5.3) hit last night. Both occurred at the Bárðarbunga caldera amidst many smaller ones. These events are commonly interpreted as effects of subsidence and disfiguration within the volcano, thus witnessing the outflow of magma chamber material into the easternmost fissure. Over 20 cm lateral displacement of distant GS-stations can be seen as a combined affect of the magma pressure and release of stress built up by tectonic plate movements (general rifting in Iceland).

As an interesting addition to all of this: some of the magma within this wide magma-filled fissure (dyke) might be supplied more or less vertically from a magma-forming region that should theoretically underlie (lengthwise) a large part of the long fissure swarm of the Bárðarbunga Volcanic System (termed a magma reservoir). The reservoir lies deeper down than the smaller magma chamber below the caldera. This extra up-flow could for example be the case at the farthest sections of the dyke but is not established. Such processes have been associated with some of the volcanic fissure eruptions in Iceland and, therefore, mentioned here to illuminate the fascinating volcanic history of the country.

The propagation of the dyke continues, as demonstrated by a few hundred earthquakes during the past 8 hours, still at considerable depth. The dyke front is now outside of the Dyngjujökull outlet glacier (of the Vatnajökull ice cap).
Recent lava flows and crater rows in a wide area in front of Dyngjujökull tell a story of local volcanic events in historical times. Written accounts from the 18th and 19th centuries and ash layers in soils, as well as in an ice core from Bárðarbunga, prove a series of volcanic events occurred in the region.

There is still no way of predicting the development but the likelihood of an eruption or series of eruptions is present.


Bárðarbunga Volcanic Activity Update –
Ari Trausti Guðmundsson 23/08/2014, 15:30

At approx. 14:00, the magma breached the crust within the Dyngjujökull outlet glacier. It will take some time for the eruptive material to melt enough ice and penetrate the ice, most likely measured in hours. Still no ash and steam rising.

At 17:30 GMT, the eruption is not powerful so there are still no signs of it on the glacier surface. It could die down, even temporarily, or it could get stronger.


Bárðarbunga Volcanic Activity Update –
Ari Trausti Guðmundsson 23/08/2014

The floor of the Barðarbunga caldera has shown signs of sustained subsiding according to the amount of magma (well over 100 million cu. metres) that has been flowing along the easternmost fissure (forming a dyke). The westernmost dyke has since far less activity over the last few days.

Today the main dyke has been receiving an increased amount of magma and gets longer and longer almost by the hour. It is now 25-30 km long and the tip (at depth) is a few kilometres away from the margin of the Dyngjujökull outlet glacier (see map from the Met. Office). Earthquake activity is very lively both along the dyke and in the caldera. Crustal displacement is evident.

All of this means that today it is more likely than ever before that an eruption will occur. It will be subglacial for the time being (glacier depth 350-400 m) but if the dyke becomes considerably longer, magma might surface outside of the ice, east of the Dyngjuháls Ridge. The former scenario means a tephra/ash-producing event plus a jökulhlaup (flood), the latter lava fountain activity, a lava flow and no water flood. There area is remote and the lava flow would not pose problems, except if it dams river channels, causing flooding but much less than a subglacial eruption would do.

Still, it is always possible that the activity will suddenly die down. However, the authorities and scientists are contemplating raising the local risk level to red. A reconnaissance flight will be carried out shortly.

bardarbunga-graphic-230814

MAP: From the Icelandic Met. Office website.


Bárðarbunga Volcanic Activity Update –
Ari Trausti Guðmundsson 20/08/2014

The earthquake activity is now largely concentrated to the northeast of the main volcano and under about 150-200 m of ice.

The chances of an immediate eruption are still less likely than yesterday, however, the volcano is still on orange alert and we will be watching developments closely.

The Icelandic Met Office demonstrates the time and magnitude of earthquakes in the region and is updated regularly here

Bárðarbunga Volcanic Activity Update – Ari Trausti Guðmundsson 20/08/2014

The earthquake activity of Bárðarbunga is somewhat fading, reducing the chance of an imminent eruption. However, the Icelandic Met Office still holds Bárðarbunga on orange alert meaning an eruption could happen at any time. From the Met Office's diagram below you can see that the western centre of earthquake activity is losing its power (mostly blue dots - old). This means that the magma injection along a vertical crack (fissure - forming what we call a dyke) is not propagating forward to any real extent. The depth is 5-10 km and one cannot rule out that the magma will surface, although it is unlikely. The eastern site, many red dots is still showing lots of signs of shuddering and there the dyke seems to be moving forward - also at a considerable depth.

The ice thickness at the eastern site is shallow (less than 200 m) meaning a flood (jökulhlaup) is still likely although will most probably be medium-sized and in sparsely populated areas. The fast flowing muddy water could still cause substantial damages to roads, bridges and farms in Öxarfjörður where the Jökulsá river meets the sea (Kelduhverfi.) Areas of immediate concern have been evacuated as a precaution and floods like these are common in Iceland with infrastructure being designed to reduce potential damage as much as possible.

In the improbable event that Bárðarbunga does erupt, it is highly unlikely that we will see air traffic disruption, similar to that of Eyjafjallajokull (despite all the media hype). The volume and the production rate of ash that Bárðarbunga could produce is not predictable although recent Bardarbunga eruptions have been relatively small. If the dyke surfaces outside the ice cap, it is possible we will see a Fimmvörðuháls-type eruption from a fissure although it would be impossible to predict the length, duration and rate of lava production.

Further to this, if all volcanic activity dies down without an eruption, it is possible that frequency of similar scenarios will increase until an eruption occurs. This could happen in the north-eastern section of the volcanic system (like now), in the south-western one (like in 1862-1864) or even within the volcanic centre proper. Such events may be repeated for years or decades like in Kröflueldar (over 20 magma injections of 9 eruptions within a period of 9 years.) A similar process is likely to have occurred in the Bárðarbunga system in the 18th century.

The earthquake activity and possible slow migration of magma into the magma chamber at Bárðarbunga started some 7-8 years ago. In comparison, the slow migration of magma for the Eyjafjallajökull eruption lasted 16 years, including two visible magma injections amidst increased earthquake activity. Katla has been brewing at least since 1998/9.

The results of this bout of activity will come clear during the next few days... and Bárðarbunga will either take a break or display an eruption.

Anyone travelling with Discover the World can do so with complete peace of mind. You will be protected by their Travel Disruption Charter, providing you with full support whatever the situation.

MAP: From the Icelandic Met. Office website.
SEE ALSO: http://gfycat.com/FaithfulRipeIntermediateegret - 3D-rendering of earthquake loci

 


Ari Trausti Guðmundsson 18/08/2014

The Bardarbunga Volcanic System is one of the largest of its kind in Iceland. A large sub-glacial volcano with a 10-km-wide caldera it is covered by ice, up to 700 m thick and forms the northwestern part of the Vatnajökull ice cap.

Fissure swarms and volcanic fissures stretch far to the southwest and northeast from Bardarbunga. Some of the volcanic fissures, with sizeable crater rows, date from the 15th, 18th and 19th century.

The activity in the 18th century included ash eruption from sites within the glacier ice, in an outlet glacier of Vatnajökull called Dyngjujökull, but most likely also some lava fountain activity on "dry land" north of Dyngjujökull. In 1862-1864 a volcanic fissure opened up and produced a lava flow to the southwest of Vatnajökull.

The present unrest within the Bárðarbunga volcanic centre and the northeastern fissure swarm started on August 16th. It includes over three thousand earthquakes (at 12:00 on August 18th) most of which are small (magnitude 1-2) but over a dozen attain magnitudes from 3.0-3.8. Seismic monitoring indicates ascending magma and GPS-measurements which have revealed displacement of the crust (2-4 cm) attributed to magma injections into the roots (or magma chamber).

It is impossible to predict how the processes will develop. A volcanic eruption could start under the ice east or north of Bardarbunga. In this case it would produce ash and pumice but in unknown quantities and with an unknown force. A large flood (jökulhlaup) is not to be ruled out and the flood path would most likely follow the glacial river Jökulsá á Fjöllum in the northeast of Iceland.

An eruption could, however, commence outside of the Dyngjujökull outlet glacier as a lava-producing event. In that case, air traffic disturbance is highly unlikely.
The third scenario would be a combination of the other two.

At the time of writing, the volcano alert is raised from yellow to orange, which means that a volcanic eruption is possible within the next few hours or days.

This diagram from the Icelandic Met Office demonstrates the time and magnitude of earthquakes in the region and is updated regularly here. 

About the Author: Ari Trausti Guðmundsson has been active as a lecturer and non-fiction writer in the fields of geology, volcanology, astronomy, environmental science and mountaineering, with close to 40 published book titles. In addition, Ari Trausti also has published short stories, six collections of poems and four novels. Educated as a geophysicist in Norway and Iceland, Ari Trausti works as a freelance consultant in the fields of geo science, tourism and environmental issues as well as writing and hosting numerous radio and television programs and documentaries. Ari Trausti is also noted as an avid mountaineer, Arctic traveler and contributor to scientific exhibitions, visitors' centers and museums in Iceland and abroad. In 2007 and 2010, he received prizes for communication in science. He is an international member of the Explorers Club. Ari Trausti was a candidate for the office of the President of Iceland in 2012.

All graphics courtesy of the Icelandic Met Office

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