Rabaul i udbrud…

Vulkanen Rabaul i East New Britain, Papua New Guinea, er i udbrud og sender kraftige askeskyer op til 60.000 fod i vejret.

Nedenstående copyright er fra John Seach: volcanolive.com

Rabaul is one of the most active volcanoes in Papua New Guinea, and one of its most dangerous. It is located on the north eastern end of New Britain Island, and is the eastern most volcano in the Bismarck arc.

The caldera has an elliptical form (14 x 9 km) and is surrounded by a steep volcanic ridge several hundred meters high. The present shape of the caldera was caused by two periods of collapse.

Rabaul Volcano, Papua New Guinea
A large explosive eruption occurred at Tarvurvur crater on 28th August 2014. Ash emissions reached an altitude of 60,000 ft.

 

Rabaul caldera

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Rabaul caldera
Rabaul.png

True-colour image of the Rabaul caldera from space.
Elevation 688 m (2,257 ft)[1]
Listing List of volcanoes in Papua New Guinea
Location
Rabaul caldera is located in Papua New Guinea

Rabaul caldera
Rabaul caldera

Gazelle Peninsula, East New Britain, Papua New Guinea
Coordinates 4°16′16″S 152°12′11″E / 4.27111°S 152.20306°E / -4.27111; 152.20306Coordinates: 4°16′16″S 152°12′11″E / 4.27111°S 152.20306°E / -4.27111; 152.20306[1]
Geology
Type Pyroclastic shield/Caldera
Age of rock ~1,400 years
Last eruption 2013 to 2014 (ongoing) [1]

The Rabaul caldera, or Rabaul Volcano, is a large volcano on the tip of the Gazelle Peninsula in East New Britain, Papua New Guinea, and derives its name from the town of Rabaul inside the caldera. The caldera has many sub-vents, Tavurvur being the most well known for its devastating eruptions over Rabaul. The outer flanks of the highest peak, a 688 metre-high asymmetrical pyroclastic shield, are formed by thick pyroclastic flow deposits.[1] There is no sign of a pyroclastic shield along the rim of the caldera, making the location likely underwater, on the caldera’s floor.

Tavurvur, a stratovolcano and a sub-vent of the caldera, is the most visibly active, continuously throwing ash. In 1994 it, and nearby Vulcan, erupted and devastated Rabaul; however, due to planning for such a catastrophe, the townsfolk were prepared and only five people were killed. One of the deaths was caused by lightning, a feature of volcanic ash clouds.[citation needed]

In 1937, Vulcan and Tavurvur erupted simultaneously, killing 507 people. This event led to the founding of the Rabaul Volcano Observatory which watches over the many active volcanoes on Papua New Guinea.[2] One eruption over several days in March 2008 released a plume of ash and water vapor that drifted northwest over the Bismarck Sea.[3]

Dunes of volcanic ash near Tavurvur

 

 

 

Subsidiary features[edit]

July 2010 eruptions[edit]

Tavurvur, as seen from space.

Vulcan, as seen from space.

Ash cloud from Tavurvur’s 2009 eruption, as seen from the Solomon Sea.

Eruptions at Rabaul’s Tavurvur volcano resumed on 23 July 2010 after nearly seven months without ash emissions. As previously noted, Tavurvur was quiet between 1 January to 8 April 2010 (BGVN 35:02).

On 9 April 2010, the Rabaul Volcano Observatory (RVO) reported that deformation measurements at Rabaul caldera during the previous 3–4 months had shown an inflationary trend with a total of 4 cm of uplift. During 2–8 April seismicity was low and variable amounts of white vapor rose from Tavurvur cone.

According to RVO, Tavurvur cone erupted on 23 July 2010 after increased seismicity, likely beneath Tavurvur cone, was detected the previous day. The series began with a few small hybrid earthquakes, followed by small low-frequency earthquakes, then continuous volcanic tremor starting at 1034 on 22 July; the eruption followed at 1300 on 23 July.

The eruption began with discharge of diffuse white plumes, followed by pink-gray fumes with low ash content. A strong odor of hydrogen sulfide was noted, and a diffuse cloud rose 1 km and drifted NW. A few hours later, observers saw billowing gray clouds, accompanied by roaring and rumbling noises. Ashfall was reported in areas to the cone’s NW and NNW.

RVO reported that, during 23–25 July, seismicity was variable. Ash emissions and ashfall continued in areas to the NW. Visibility remained poor in Rabaul town (3–5 km NW of Tavurvur) due to ash made airborne by the passage of moving vehicles. Ash emissions ceased on 25 July. Later that day and into 26 July only diffuse brown-tinted vapor plumes were emitted and seismicity was very low.

After the eruption of 23–25 July, GPS data showed deflation of Tavurvur cone. Seismicity was very low, and diffuse white plumes were emitted during 26–30 July.[4]

 

 



Information fra Island om Bardarbunga

Bardarbunga 2014

For detailed information on seismicity go to the IMO (Icelandic Met Office) webpage

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.

5. September 2014

Major element composition of lava erupted in the second Holuraun phase (ICP):

5th September 2014 12:20 – from the Scientific Advisory Board

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:   

  • At about 7:00 UTC this morning RÚV reported that new eruptive fissures had opened to the south of the on-going eruption.
  • At 8:30, a surveillance flight with scientists from the IMO and University of Iceland observed the following:
    • Two new eruptive fissures formed south of the previous eruption site in Holuhraun, in a graben, that had formed above the intrusion, about 2km away from Dyngjujökull.
    • The eruptive fire fountains from the new fissures are substantially smaller than in the older fissure. Steam and gas rises in a south eastern direction from the fissure.
    • The cauldron in Dyngjujökull seems to have grown deeper since the last observation.
    • No changes are visible in Bárðarbunga.
  • Substantial amounts of SO2 are still being released to the atmosphere in association with the eruption.
  • Conductivity measurements show a slight increase in conductivity in Jökulsá á Fjöllum.
  • Some tremor was detected on seismometers shortly after 3:00 UTC last night. It decreased at about 6:00 UTC this morning.
  • Considerable activity is in the northern fissure (fissure 1) and the height of the steam cloud is about 15,000 feet.
  • There are no indications of the eruption in Holuhraun being in decline. The lava from fissure 1 continues to flow to the east north east and has grown in area since yesterday.
  • Seismicity in the area is similar to yesterday’s activity. About 170 earthquakes were detected since midnight. Two earthquakes of magnitudes 4,4 and 5,3 were detected in the Bárðarbunga caldera region at around midnight UTC.
  • GPS displacements have continues to decrease and are now within uncertainty limits.
  • Four scenarios are still likely:
    • The migration of magma could stop, resulting in a gradual reduction in seismic activity and no further eruptions.
    • The dike could reach the Earth’s surface at different locations outside the glacier. Lava flow and/or explosive activity cannot be excluded.
    • 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.
    • 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’.

New eruption fissure has opened in Holuhraun! – At about 7:00 UTC this morning RÚV reported that new eruptive fissures had opened to the south of the on-going eruption.

Photos from flight this morning over the new eruption fissure in Holuhraun. First photo shows the “older” fissure in the background, but that one is still very active. Photos from Þóra Árnadóttir

4. September 2014
04.09.2014, 12:20 UTC – Conclusions of the Scientific Advisory Board of the Icelandic Civil Protection:

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.

  • The intensity of the ongoing eruption in Holuhraun is not declining. Lava is flowing toward ENE and it has been elongated considerably since yesterday. Since this morning, a preliminary estimate of lava field extension is about 10.8 km2.
  • Seismic activity is still detected in the northern part of the dyke intrusion, along the eruption site and extending south below Dyngjujökull. Event rates are lower than in recent days, 180 earthquakes have been detected since midnight until noon. Four events larger than M4 have been detected in Bárðarbunga caldera. The largest one (M4.8) occurred last night at 03:09.
  •  The low frequency tremor seen yesterday disappeared last night but started again this morning, however minor compared to yesterday. The source of the tremor is not certain however possible explanation could be magma-water interaction although this interpretation has currently not been confirmed by other observations.
  • There are no signs of a subglacial eruption under Dyngjujökull. No obvious changes such as increased water flow or cauldrons on the glacier surface were observed from scientists on board TF-SIF yesterday. Water meters in Jökulsá á Fjöllum do not show any unusual changes in discharge and electric conductivity.
  • The GPS time series indicate slower rate of deformation in the last 24 hours. The current deformation pattern north of Vatnajökull still suggests volume increase in the dyke. No significant signs of deformation are observed around Bárðarbunga.
  • There have been no observations of ash-fall away from the eruption site. Ash production is negligible.
  • Sulphur dioxide emission continues. Low-wind speed condition is present in the area at the moment. Based on radar images the eruption cloud from today (composed of steam and volcanic gases) has not drifted far away and is mostly concentrated around the eruption site. Stations measuring SO2 further away from the eruption site are showing concentration below health and safety thresholds. Since this morning, the cloud reaches 6 km of altitude. The volcanic cloud will drift towards south in the coming hours due to wind rotation.
  • Four scenarios are likely:
  • The migration of magma could stop, resulting in a gradual reduction in seismic activity and no further eruptions.
  • 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.
  • 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.
  • 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’.

3. September 2014

Modelling of continuous GPS measurements north of Vatnajökull show significant horizontal deformation during Aug. 31 to end of day Sept. 2, indicating a volume increase in the dike intrusion. Radar images show a graben formed south of the eruption and cracks extend onto the edge of Dyngjujökull (see images below). This demonstrates large horizontal and vertical displacements over the dike. As long as there is a net influx of magma to the dike, the eruptive fissure could extend further south, causing increased hazard in the area.

Blue arrows (with 95% confidence ellipses) are measured displacements, red arrows show the model prediction. Green line is the surface projection of the dike model. Earthquakes recorded by the IMO during this time are shown with red dots, green stars indicate M>4 events.

Riverine discharge and conductivity in rivers draining potential eruptions sites within the Vatnajökull glacier. Background data and observations (pdf) Eydís Salome Eiríksdóttir, Iwona Monika Galeczka, Rebecca Anna Neely and Sigurdur Reynir Gíslason

Volcanic gas hazard (pdf file)

Magma contains dissolved gases that are released into the atmosphere during eruptions. Gases are also released from magma that either remains below ground (for example, as an intrusion) or is rising towards the surface. In such cases, gases may escape continuously into the atmosphere from the soil, volcanic vents, fumaroles, and hydrothermal systems.
The major volcanic gases emitted from basaltic magma are H2O, CO2, SO2, H2, CO, H2S, HCl and HF. The most abundant gas is water vapor (H2O), followed by carbon dioxide (CO2) and sulfur dioxide (SO2).

03.09.2014, 12:20 UTC –  Conclusions of the Scientific Advisory Board of the Icelandic Civil Protection:
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.
• Earthquake activity continues – around 160 earthquakes have been recorded since midnight today. Seismicity is occurring mostly beneath the northern edge of Dyngjujökull. A magnitude 5.5 earthquake occurred at 03:08 UTC today on the northern side of the Bárðarbunga caldera.
• GPS measurements show that the volume of the dyke intrusion has increased since the beginning of the eruption; this signifies that more magma is entering the dyke than is being erupted.
• Despite no sign of a volume decrease in the dyke, GPS measurements show that the rate of ground deformation has slowed.
• Recent radar images show a 0.5 – 1 km wide depression that has formed both in front of and beneath Dyngjujökull. Signs of the depression extend about 2 km into the ice margin. The increasing thickness of the glacier decreases the visual extent of fracturing associated with the depression, so it is likely that the area extends further beneath Dyngjujökull.
• In light of GPS, radar and seismic results, it is possible that the ongoing eruption could progress southward under Dyngjujökull. This would lead to immediate flooding hazards on the floodplain in front of Dyngjujökull. Consequently, risk assessments for scientists working in the area will be reviewed.
• The volcanic eruption continues on Holuhraun; the main path for lava is to the east-north-east.
• At 08:00 UTC today the total area of the lava flow was estimated at 7.2 km2.
• There have been no observations of ash-fall. Ash production is almost negligible.
• Sulphur dioxide continues to be detected near to the eruption site. The eruption cloud is drifting to the north-east from the eruption site.
• Four scenarios are 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’.

New map of the advance of lava – 2. September 2014, 14:00

The field group of the IES measured the northern and eastern edge of the lava flow at 14:00 yesterday.  The lava was then about 6 km long and had advanced about 2 km in 24 hours.

The discharge of magma from the fisssure is estimated to have been 100-150 m3/s in the 24 hours before 14:00, about one third of the rate on the first day.


2. September 2014

Photomicrograph of silicate melt inclusions in plagioclase crystals picked from sample 11 erupted on 31st of August.


02.09.2014, 12:20 UTC – Conclusions of the Scientific Advisory Board of the Icelandic Civil Protection:

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.

A noticeable decrease in seismicity has occurred during the last 24 hours. The level of activity is approximately half of that during recent days. Since midnight today, around 300 earthquakes have occurred. At the same time yesterday, 01 September, around 500 earthquakes had been detected.
The rate of deformation at GPS sites closest to the dyke intrusion has decreased. Together with an overnight decrease in seismicity, this implies that magma inflow appears to match magma outflow at the eruption site.
The eruption has not created any ash-fall.
A white plume of steam and gas rises from the eruption on Holuhraun, reaching an elevation of about 4.5 km above sea level. Downwind, a volcanic cloud extends from the eruption site. Yesterday afternoon, a white cloud from the eruption extended 60 km to the north-north-east. In comparison to yesterday, more sulphur dioxide has been measured in the eruption cloud.
Sandstorms on the floodplain around the eruption site have contributed fine-grained particles to the eruption cloud. This was seen as a light-brown haze earlier today near to Egilsstaðir.
The eruptive fissure is about 1.5 km in length, positioned about 4.5 km from the ice margin of Dyngjujökull. At 14:00 UTC yesterday, the lava flow was 4.2 km2 in area. At 08:00 UTC the edge had extended 1.5 km to the east-south-east. The eruption continues, although there appears to have been a slight decrease in activity compared to yesterday. It remains unclear how the situation will develop. Four scenarios are still considered most likely:

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

Observations of tephra deposits from 29-08-2014 by the lava producing event at Holuhraun, North Iceland

Two very small tephra fall sectors are present on the west side of the fissure.

The first sector is comprised of fine-grained grey ash with origin at the southern part of the active fissure. This tephra fall rests on the surface of two fresh and westward trending lava flows surrounding the venting area on the southern end of the fissure. The deposit was distributed from about 150 m along the fissure and thickness of the fall deposit at the vents is 2 cm. 10 m to the west of the vents the thickness drops to 0.5 cm. Further away from the vents the deposit was eroded and remobilized. Thickness estimated to be less than mm in the area >20 m away from craters. Beneath the grey ash is a 0.3-0.4 cm thick lithic layer, comprised of angular and rounded lithics of approximate 0.1-0.2 cm in diameter, this lithic layer was only observed within 10m of the vent.

The second tephra sector is a red-brown ash fall observed close to the largest vent on the new fissure. The deposit reached up to 10 m from its vents and consists of red-oxidized and black juvenile fragments along with grains of plagioclase. The mean grain size of this deposit ranges from 0.2 cm at vent to 0.1 cm 10 m from vent. Water-escape features and dampness of the deposit indicates moist emplacement. Thickness at vent is 0.4-0.6 cm and 10 m west of the vent it has dropped to 0.2 cm.

Jónas Gudnason, Kate Gallegher, and Johanne Schmith.

 

New COSMO-SkyMED decending interferogram spanning the period 13 – 29 August 2014

COSMO-SkyMED descending wrapped interferogram spanning the period 13 – 29 August 2014. Each interferometric fringe corresponds to 15 millimeters of relative change in range from ground to satellite.  The highest fringe rate is observed closest to the subsurface dike causing the deformation. Decorrelation in the interferogram is caused by large amount of deformation at the surface, lava flows formed in an eruption between the acquisition of the images used, and surface change due to unstable sand.
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

31. August 2014
Daily status report 31. August 2014 – compiled by IMO (Icelandic Met Office) and IES (Institute of Earth Scienses) (pdf)

Bárðarbunga: 31.08.2014, 12:00 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:

·        A lava eruption started in Holuhraun shortly after 04 AM, on the same volcanic fissure, which erupted earlier this week. The fissure is estimated to be 1,5 km long. It was detected on Míla´s web-camera at 05:51 AM. Fewer earthquakes seem to follow the event than in the previous eruption, but more lava is being extruded.

·        At 07 AM the lava flow was around 1 km wide and 3 km long towards northeast. The thickness was estimated a few meters, the flow about 1000 m3 pr second.

·        Approximately 500 earthquakes were detected in the area and smaller than before. The strongest earthquake, M3.8 was in the Bárðarbunga caldera. Poor weather conditions prevail in the area, which makes detection of smaller earthquakes difficult.

·        GPS measurements show continued movements north of Dyngjujökull.

·        Gas emissions rise to a few hundred meters above the fissure.

·        Weather conditions make it difficult to follow the progression of the eruption, but scientists are in the area, using every opportunity to acquire information on gas and lava outflow.

·        Weather conditions do not allow overflight at this time. The opportunity to fly over the area will be assessed later today.

From the Icelandic Met Office:

The Aviation Colour Code for Bárðarbunga is at ‘red’ and the code for Askja at ‘yellow’.

 

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: Ármann Höskuldsson

 

An upgraded plot of Bárðarbunga seismicity and dike propagation based on revised earthquake locations from IMO, circle size represents earthquake magnitude. The three eruptions are marked by orange colored bars. Note how rapid dike propagation northwards coincides with the SE Bárðarbunga flank eruption whereas a slight decrease in dike propagation is associated with the first Holuhraun eruption.

Bryndís Brandsdóttir

 

30. August 2014

Bárðarbunga: 30.08.2014, 12:00 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:

·       Earthquake activity continues on a 15-km-long region of the dyke intrusion, extending both into the Dyngjujökull glacier and the region north of the ice margin. Earthquakes have not migrated northwards during the last two days. Seismicity remains high and, since midnight, about 700 earthquakes have been detected in the region.

·       The largest earthquakes since midnight include: (i) a magnitude 4.5 event on the northern side of the Bárðarbunga caldera at 02:35 UTC; (ii) a magnitude 4.2 earthquake in the same region at 06:18 UTC; and (iii) a magnitude 5.4 earthquake on the south-eastern edge of the Bárðarbunga caldera at 07:03 UTC. During the last two weeks, several earthquakes of similar size have occurred on the edge of the Bárðarbunga caldera. These earthquakes are interpreted as signs of stress changes in the region of the caldera.

·       Over 20 micro-earthquakes have been detected in the Askja region. It is thought that these earthquakes have occurred due to stress changes north of the dyke intrusion.

·       GPS measurements show continued horizontal movements north of Vatnajökull due to formation of the dyke intrusion on the northern edge of the ice-cap.

·       No unusual changes in the discharge or electrical conductivity of Jökulsá á Fjöllum have been detected. The same applies to other rivers draining from north-western Vatnajökull.

·       A sample of newly erupted lava was taken from Holuhraun yesterday; analysis is ongoing.

·       There are no indications that the intensity of the activity declining.

·       At this moment it is unclear how the situation will develop. However, four scenarios are 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 north of Dyngjujökull causing another eruption, possibly on a new fissure. Such an eruption could include lava flow and (or) explosive activity.

o   The intrusion reaches the surface and an eruption occurs again 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’.

29. August 2014

Bárðarbunga: 29.08.2014, 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:
• At 00:02 UTC signs of a lava eruption were detected on web camera images from Mila. The web-camera is located at Vaðalda, north-east of the eruption site.
• Around midnight, weak signs of increased tremor were apparent on IMO’s seismic stations near to the eruption site.
• At 00:20 UTC scientists in the field from the Icelandic Met Office, Institute of Earth Sciences and Cambridge University confirmed the location of the eruption.
• The eruption occurred on an old volcanic fissure on the Holuhraun lava field, about 5 km north of the Dyngjujökull ice margin. The active fissure was about 600 m in length.
• A small amount of lava drained from the fissure and by around 04:00 UTC, lava flow is thought to have stopped.
• According to seismic data and web-camera imagery, the eruption peaked between 00:40 and 01:00 UTC.
• At the beginning of the eruption, seismic activity decreased, although seismicity has since returned to levels observed in recent days.
• Aerial observations by the Icelandic Coastguard show that only steam is rising from the site of the lava eruption.
• There are no indications that the intensity of the activity declining.
• At this moment it is unclear how the situation will develop. However, three scenarios are considered most likely:
  • The migration of magma could stop, resulting in a gradual reduction in seismic activity and no further eruptions.
  • The dike could reach the Earth’s surface north of Dyngjujökull causing another eruption, possibly on a new fissure. Such an eruption could include lava flow and (or) explosive activity.
  • The intrusion reaches the surface and an eruption occurs again 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.
• Other scenarios cannot be excluded. For example, an eruption inside the Bárdarbunga caldera.
From the Icelandic Met Office:
At 10:00 UTC, IMO changed the Aviation Colour Code for Bárðarbunga to ‘orange’, signifying that significant emission of ash into the atmosphere is unlikely. The aviation colour-code for the Askja volcano remains at ‘yellow’.

An overview of Bárðarbunga seismicity and dike propagation, August 16th-28th – Bryndís Brandsdóttir

Revised earthquake locations from IMO, circle size represents earthquake magnitude. Dike propagation commences following termination of Kistufell activity. Advances in dike probation (marked by vertical lines) are related to large deflation events in Bárðarbunga.

29. August 2014 at 7:10 UTC

An eruption has started in Holuhraun north of Dyngjujökull at 00:02 this morning. An approximately 1 km long fissure (first estimate of scientists in the field) has opened, the eruption is purely effusive and no signs of explosive activity or ash emission has been detected so far. Based on volcanic tremor data, the eruption was strongest between 00:20 and around 02:00, peaking between 00:400 and 01:00. It has been decreasing until about 02:30 and is stabily active since.
Seismic activity has decreased as a result of the pressure release, however a significant amount of earthquakes is still detected in the magma dike, between the eruption site and south to about 5 km into Dyngjujökull. Strongest events last night were 3.8 in the caldera of Bárðarbunga at 04:37, as well as 2.9 at 05:39 and 3.5 at 06:38 in the dike. These earthquake are very closely monitored, but no significant change volcanic activity following these has been observed so far.

New COSMO-SkyMED ascending and decending interferograms

COSMO-SkyMED ascending interferogram spanning the period 11th August 2014 – 27th August 2014. Each fringe represents ~1.5 cm of displacement in the satellite’s line-of-sight.

 

 

 

 

 

 

 

 

 

 

COSMO-SkyMED descending interferogram spanning the period 10th August 2014 – 26th August 2014. Each fringe represents ~1.5 cm of displacement in the satellite’s line-of-sight.

 

 

 

 

 

 

 

 

 

Processing carried out using CSK Products, © ASI (Italian Space Agency) – 2014, delivered under an ASI license to use. COSMO-SkyMed images have been provided in the framework of the Geohazard Supersite Initiative.

Model of surface deformation, incorporating both GPS and satellite data, spanning the period 10th August 2014 – 27th August 2014. The vertical plane represents the location of the dike at depth (red colours show maximum opening). The model indicates that the eruption (red star) is coming from the patch with maximum opening (5m), right at the surface (dark red patch). Black dots show earthquakes during the same time period (since the start of unrest on the 16th August 2014) located by the Icelandic Met Office. Model processed by A.J.H.

Interferogram processing carried out using CSK Products, © ASI (Italian Space Agency) - 2014, delivered under an ASI license to use. COSMO-SkyMed images have been provided in the framework of the Geohazard Supersite Initiative.

29. August 2014

IMO has visual confirmation via scientists in the field and via webcam that a A fissure eruption (hraungos / sprungugos) has started north of Dyngjujökull (Holuhraun). Based on webcams and seismic data the eruption started at 00:02 (29/8/14).

No volcanic ash has been detected with the radar system at the moment. The wind field condition in the area are wind blowing toward NW at 12 m/s at 5 km altitude. Seismic eruption tremor is low indicating effusive eruption without significant explosive activity.

Satellite infrared images (Seviri 3,9 micron) confirm thermal anomaly at 00:38.

The color code at Bárðarbunga has been changed to red.

28. August 2014

Bárðarbunga: 28.08.2014, 12:00 UTC

Conclusions of the Scientific Advisory Board of the Icelandic Civil Protection

Scientists from the Icelandic Meteorological Office and the Institute of Earth Sciences, together with representatives of the Civil Protection in Iceland, met today to discuss the on-going unrest at the Bárðarbunga volcano.

This morning, there was a flight over the Bárðarbunga area and the surface of the glacier was surveyed. No changes to the ice crevasses southeast of Bárðarbunga, that were seen yesterday evening, were observed. These crevasses were likely formed due to melting at the ice bottom.

The depressions have been located southeast of the Bárðarbunga caldera, in all likelihood within the water divide of the river Jökulsá á Fjöllum. There are three circular crevasse formations, about 5 km in total length. The ice thickness in the area is 400-600 m.

The water level in Grímsvötn Lake has been surveyed and has likely risen by about 5-10 m in the last days, which corresponds to an addition of 10-30 million m3 of water in the lake. A slight increase in conductivity in Köldukvísl River was measured this morning, but the cause is yet unknown. No change has been measured in the Hágöngulón lagoon, Jökulsá River and Skjálfandi River. It is assumed, that the water from the cauldron has flowed into the Grímsvötn Lake or the river Jökulsá á Fjöllum.

The seismic activity is similar to that of the last days. Around midnight, three earthquakes of magnitude around 4 were recorded and one of magnitude 5 at 08:13 this morning, all located within the Bárðarbunga caldera.

Shortly before 08:00 this morning, there was a slight increase in seismic activity in Askja volcano. Changes in the stress field due to expansion caused by the dyke have an effect on the Askja area.

Since yesterday, the length of the dyke under Dyngjujökull has increased by 1-1.5 km to the north, which is considerably less than in the last days. The dyke has now reached the fissure system of the Askja volcano and GPS measurements indicate that the area there is greatly affected.

The conclusions from the meeting of the Scientific Advisory Board of the Icelandic Civil Protection will continue to be published at around noon, after the meeting, if necessary.

From the Icelandic Met Office: The Aviation Colour Code remains at the ‘orange’ level for Bárðarbunga. The Aviation Colour code is raised to ‘yellow’ level for Askja.

 

New page showing cumulative displacements at cGPS stations near Bárðarbunga and earthquakes

 

 

27. August 2014

Bárðarbunga: 27.08.2014, 11:50 UTC – Conclusions of the Scientific Advisory Board of the Icelandic Civil Protection
Scientists from the Icelandic Meteorological Office and the Institute of Earth Sciences, together with representatives of the Civil Protection in Iceland, met today to discuss the on-going unrest at the Bárðarbunga volcano.
These are the conclusions of the meeting: • Intense seismi…city continues. Over 700 earthquakes have been recorded since midnight. Earthquakes are occurring mostly beyond the edge of the Dyngjujökull glacier and the intrusion itself has migrated about 1 km northwards since yesterday. • At 00:16 UTC today, a magnitude 5.3 earthquake occurred in the caldera of Bárðarbunga. At 02:50 UTC, another similar-sized earthquake (magnitude 5.2) took place in the same region. • At 01:52 UTC, a magnitude 4.5 earthquake was detected on the eastern side of the Askja volcano. This was followed by a few micro-earthquakes in the same area. • The dyke intrusion beneath Dyngjujökull is thought to be about 40 km in length. • Modelling of GPS data indicates that about 20 million cubic metres of magma have been added to the volume of the intrusion in the last 24 hours. • Modelling results suggest that the dyke intrusion is causing stress changes over a large area, including the region to the north of the dyke’s extent; this could account for the increased seismicity at Askja volcano. • There are no indications that the intensity of the activity declining. • From today, the afternoon status report will no longer be produced. However, if the situation escalates (i.e. imminent signs of an eruption), daily status reports will be reintroduced. The results of the scientific advisory board (this factsheet) will continue to be distributed daily at around midday.
From the Icelandic Met Office: The Aviation Colour Code remains at the ‘orange’ level for Bárðarbunga.

26. August 2014

Daily status report 26. August 2014 – compiled by IMO (Icelandic Met Office) and IES (Institute of Earth Scienses) (pdf)

26. August 2014 kl. 11:50 – 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 Advisory Board

The following points were the conclusion at a meeting of the Advisory Board today:

  • Intense seismicity continues. Over 500 events have been recorded since midnight.
  • Seismicity continues to migrate northward. Seismicity is now concentrated on the 10 km long tip of the dike extending 5 km beyond the edge of the Dyngjujökull glacier.
  • At 01:26 this morning an earthquake of magnitude 5,7 was observed beneath the Bárðarbunga caldera.
  • The dyke beneath Dyngjujökull is now thought to be close to 40 km long. Modelling of GPS data indicates that about 50 million cubic meters of magma have added to the volume in the last 24 hours.
  • There are no indications that the intensity of the activity declining. The following three scenarios are still considered most likely:
    • The migration of magma could stop, accompanied by a gradual reduction in seismic activity.
    • The dike could reach the surface of the crust, starting an eruption. In this scenario, it is most likely that the eruption would be near the northern tip of the dyke. This would most likely produce an effusive lava eruption with limited explosive, ash-producing activity.
    • An alternate scenario would be the dyke reaching the surface where a significant part, or all, of the fissure is beneath the glacier. This would most likely produce a flood in Jökulsá á Fjöllum and perhaps explosive, ash-producing activity.
  • Other scenarios cannot be excluded. For example, an eruption inside the Bárðarbunga caldera is possible but presently considered to be less likely.

From the Icelandic Met Office: The Aviation Color Code remains at the ‘orange’ level.

25. August 2014

Daily status report 25. August 2014 – compiled by IMO (Icelandic Met Office) and IES (Institute of Earth Scienses) (pdf)

25.08.2014 11:00 – 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 Advisory Board

The following was presented at a meeting of the Advisory Board at 10 am today:

  • Intense seismicity continues. Over 700 events have been recorded since midnight.
  • Seismicity continues to migrate northward. Seismicity is now concentrated on the 10 km long tip of the dike extending 5 km beyond the edge of the Dyngjujökull glacier.
  • At 20:39 last night an earthquake of magnitude ~5 was observed beneath the Bárðarbunga caldera. Since then earthquakes in the caldera have been smaller.
  • The dike beneath Dyngjujökull is now thought to be close to 35 km long. Modelling of GPS data indicates that it contains about 300 million cubic meters of magma.
  • Additional stations for continuous GPS monitoring will be installed north of Vonarskarð and on Urðarháls within a few days.
  • There are no indications that the intensity of the activity declining.
  • Currently, three scenarios are considered most likely:
  • The migration of magma could stop, attended by a gradual reduction in seismic activity.
  • The dike could reach the surface of the crust, starting an eruption. In this scenario, it is most likely that the eruption would be near the northern tip of the dike. This would most likely produce an effusive lava eruption with limited explosive, ash-producing activity.
  • An alternate scenario would be the dike reaching the surface where a significant part, or all, of the fissure is beneath the glacier. This would most likely produce a flood in Jökulsá á Fjöllum and perhaps explosive, ash-producing activity.
  • Other scenarios cannot be excluded. For example, an eruption inside the Bárdarbunga caldera is possible but presently considered to be less likely.

24. August 2014

Daily status report 24. August 2014 – compiled by IMO (Icelandic Met Office) and IES (Institute of Earth Scienses) (pdf)

23. August 2014

Bárðarbunga – Dyngjujökull – aircraft observations on 23 August


Detailed observations from TF-SIF, the Coast Guard Dash 9 were performed in the afternoon of the 23rd of August.  The observations revealed that no signs of an ongoing eruption could be detected and it is concluded that a subglacial eruption did not happen.  Increased low frequency tremor observed on that day must therefore have a different explanation.

The SAR-radar images obtained by the aircraft in the afternoon of 23 August show that no changes have occurred, neither subsidence, or unusal discharge of rivers.

Experience from subglacial eruptions in the past suggests the following:

·       Large scale melting of ice occurs if an eruption takes place beneath a glacier.  Even very small eruptions (like the eruption at Fimmvorðuháls that preceded the Eyjafjallajökull eruption in 2010) if they had taken place under ice, would melt of the order of 100 cubic meters per second of ice and cause notable increase in discharge in glacial rivers.

·       In most cases meltwater will flow away from the eruption site towards the edge of the glacier.  If an eruption occurs in late summer the drainage system at the bottom of the glacier is well developed.  This means that water will drain fast to the edge of the glacier.  For example, if an eruption site is located under ice, 5-10 km from the edge of the glacier it is expected that meltwater will reach the edge in about an hour.

·       The time it takes an eruption to melt its way to the surface is strongly dependent on the ice thickness.  As an example, the moderate sized eruption of Grímsvötn in 2004, melted through 150 m of ice in about one hour while the more powerful Gjálp eruption in 1996 took 31 hours to melt through 600 m of ice.

·       The above implies that the meltwater from an eruption beginning under e.g. 500 m of ice in Dyngjujökull would emerge from the glacier several hours before the eruption melts through the glacier sparking off an explosive eruption because of magma-water interaction.

Magnús Tumi Guðmundsson
Further material:

Hazard due to eruptions, including subglacial ones (Jökull 2008): https://notendur.hi.is//~mtg/pdf/2008Jokull58_MTGetal_volchaz.pdf On the volcano-ice interaction in the Gjálp eruption: https://notendur.hi.is//~mtg/pdf/1997Nature_MTG_FS_HB.pdf and https://notendur.hi.is//~mtg/pdf/2003BullVolc66_MTGetal_Gjalp.pdf And on eruptions in glaciers in general: https://notendur.hi.is//~mtg/pdf/2005SubglacVolcAct_MTG-DQS.pdf https://notendur.hi.is//~mtg/pdf/2003GeopMono140_MTG_magma-ice-water.pdf

Daily status report 23. August 2014 – compiled by IMO (Icelandic Met Office) and IES (Institute of Earth Scienses) (pdf)

23.08.2014, 20:30 UTC – Bárðarbunga

Information from Icelandic Met Office (IMO)

  • At 11:20 UTC today, seismic tremor measurements gave a strong indication that an eruption beneath Dyngjujökull was occurring. Tremor levels decreased during the afternoon, although intense earthquake activity continues.
  • At 14:00 UTC, an over-flight was made to Bárðarbunga by the Icelandic Coastguard with scientists from the Icelandic Meteorological Office and the University of Iceland, in addition to a representative from the National Commissioner of the Icelandic Police.
  • The over-flight covered the north-western region of the Vatnajökull ice-cap in clear conditions. Both visual observations and radar measurements confirmed no significant changes on the surface of Vatnajökull. Likewise, there were no signs of floodwater draining from the ice margin.
  • During three hours of aerial surveillance, there were no obvious signs of volcanic activity.
  • In light of the intense, ongoing earthquake activity and crustal deformation at Bárðarbunga, the Icelandic Meteorological Office has decided that the aviation colour-code should remain ‘red’, signifying that an eruption is either imminent or in progress. The situation will be reassessed tomorrow morning.

23rd August 2014 14:10 – a small eruption under Dyngjujökull?

Information from Icelandic Met Office (IMO)

  • The Icelandic Coast Guard airplane TF-SIF is flying over the area with representatives from the Civil Protection and experts from the Icelandic Met Office and the Institute of Earth Sciences. Data from the equipment on board is expected later today.
  • Data from radars and web-cameras is being received, showing no signs of changes at the surface.
  • The estimate is that 150-400 meters of ice is above the area.
  • The aviation color code for the Bárðarbunga volcano has been changed from orange to red.
  • Some minutes ago (14:04), an earthquake occurred, estimated 4.5 in magnitude.

22. August 2014

Daily status report 22. August 2014 – compiled by IMO (Icelandic Met Office) and IES (Institute of Earth Scienses) (pdf)

GPS time series around Bárðabunga, including recently installed continuous GPS station GSIG in Kverkfjöll


GPS time series for the last 3 months http://strokkur.raunvis.hi.is/gps/DYNC_3mrap.png http://strokkur.raunvis.hi.is/gps/HAFS_3mrap.png http://strokkur.raunvis.hi.is/gps/GFUM_3mrap.png http://strokkur.raunvis.hi.is/gps/VONC_3mrap.png http://strokkur.raunvis.hi.is/gps/GSIG_3mrap.png

1 year GPS time series http://strokkur.raunvis.hi.is/gps/DYNC_rap.png http://strokkur.raunvis.hi.is/gps/HAFS_rap.png http://strokkur.raunvis.hi.is/gps/GFUM_rap.png http://strokkur.raunvis.hi.is/gps/VONC_rap.png http://strokkur.raunvis.hi.is/gps/GSIG_rap.png

Extended time series http://strokkur.raunvis.hi.is/gps/DYNC_08.png http://strokkur.raunvis.hi.is/gps/HAFS_08.png http://strokkur.raunvis.hi.is/gps/GFUM_08.png http://strokkur.raunvis.hi.is/gps/VONC_08.png

21. August 2014

Daily status report 21. August 2014 – compiled by IMO (Icelandic Met Office) and IES (Institute of Earth Scienses) (pdf)

20. August 2014

Daily status report 20. August 2014 – compiled by IMO (Icelandic Met Office) and IES (Institute of Earth Scienses) (pdf)

Since the start of the earthquake swarm, precise continuous GPS stations located in the vicinity of the Bárðarbunga central volcano have shown movements which indicate that magma is propagating in the crust.  During the period between 8 am on the 15th of August and 4 pm on the 18th of August a GPS station on Dyngjuháls moved 5,4 cm towards the northwest and a GPS station near Grímsvötn moved 1,8 cm towards the south.

The map shows locations of earthquakes detected by the SIL network of the Icelandic Meteorological Office.  Movements on continuous GPS stations are shown as blue arrows, the continuous stations are run in cooperation between the Institute of Earth Sciences at the University of Iceland and by the Icelandic Meteorological Office.  Fractures and eruptive fissures in the area are denoted by yellow and red lines respectively.

The orange arrows show a model on how the GPS stations could be moving if a dike was propagating (see thick red line on map), and magma was draining away from the Bárðarbunga magma chamber („Mogi center“).  It has to be mentioned, however, that this model is only one of several models that can explain the movements seen on the GPS stations.

——-
Possible model of the dike intrusion:

Length of dike: 20 km

Height of dike: 2,1 km

Opening of dike: 1,6 m

Depth to the dike: 3 km

Volume of dike: 80-90 million cubic meters

Strike = 47,51, dip 90 (predefined)

Depth to Mogi source: 1 km

Volume change of Mogi source:

-10 til -30 million cubic meters

——-

References

GPS data – Institute of Earth Sciences, University of Iceland and the Icelandic Meteorological Office

Model calculations:  Elías Rafn Heimisson, Freysteinn Sigmundsson

Earthquakes: Icelandic Meteorological Office (part of the earthquakes have not been reviewed).

Fractures near Tungnafellsjökull: Þórhildur Björnsdóttir and

Páll Einarsson (Jökull, 2013).

Fractures and eruptive fissures in the Northern Volcanic Zone: Ásta Rut Hjartardóttir

and Páll Einarsson (2012), Ásta Rut Hjartardóttir (2013).

Background:  IS50 database of the National Land Survey of Iceland.

19. August 2014

3m http://strokkur.raunvis.hi.is/gps/DYNC_3mrap.png http://strokkur.raunvis.hi.is/gps/HAFS_3mrap.png http://strokkur.raunvis.hi.is/gps/GFUM_3mrap.png http://strokkur.raunvis.hi.is/gps/VONC_3mrap.png 1yr http://strokkur.raunvis.hi.is/gps/DYNC_rap.png http://strokkur.raunvis.hi.is/gps/HAFS_rap.png http://strokkur.raunvis.hi.is/gps/GFUM_rap.png http://strokkur.raunvis.hi.is/gps/VONC_rap.png long http://strokkur.raunvis.hi.is/gps/DYNC_08.png http://strokkur.raunvis.hi.is/gps/HAFS_08.png http://strokkur.raunvis.hi.is/gps/GFUM_08.png http://strokkur.raunvis.hi.is/gps/VONC_08.png

18. August 2014

Melissa Pfeffer posted this message on Basecamp:

Bárðarbunga aviation color code changed to orange

The intense seismic activity that started on 16 of August at Bárðarbunga persists. Very strong indications of ongoing magma movement, in connection with dyke intrusion, is corroborated by GPS measurements. There are currently two swarms: one to the E of Bárðarbunga caldera and one at the edge of Dyngjajökull just E of Kistufell. At 2.37 am on the 18th a strong earthquake (M4) was located in the Kistufell swarm. This is the strongest earthquake measured in the region since 1996. As evidence of magma movement shallower than 10 km implies increased potential of a volcanic eruption, we are moving the Bárðarbunga aviation color code to orange (after a reevaluation of the events in the last days).

Presently there are no signs of eruption, but we cannot exclude that the current activity will result in an explosive subglacial eruption, leading to an outburst flood (jökulhlaup) and ash emission. The situation is monitored closely.

 

The update map is available at:

http://en.vedur.is/earthquakes-and-volcanism/volcanic-eruptions/

17. August 2014

An intense seismic swarm is currently taking place under the eastern part of Bárðarbunga. Between 03:04 and 13:00 on August 16th a total of 189 earthquakes occurred (max. M2.9).  The seismic swarm continues and continuous GPS stations have detected deformation that confirm magma movements associated with intrusive activity. No indications of surface magma extrusion beneath the ice cap have been observed. If the activity progresses towards an eruption, a scenario could involve a subglacial, or partly subglacial eruption, at the northwestern part or edge of Vatnajökull, with a jökulhlaup in the Jökulsá á Fjöllum river towards the north.

This is the largest seismic swarm seen in Bárðarbunga since the end of September 1996, in the days leading to the Gjálp eruption.  The area is covered by Vatnajökull and the ice thickness varies from 100-200 at  the caldera rims of Bárðarbunga to over 800 m within the Bárðarbunga caldera. IMO, IES and Civil Protection are monitoring the situation – the seismic activity can be observed at www.vedur.is.

A direct link to the Vatnajökull seismic map is: http://www.vedur.is/skjalftar-og-eldgos/jardskjalftar/vatnajokull/#view=map

Publications:

Hartley, M. E., and T. Thordarson (2013), The 1874–1876 volcano-tectonic episode at Askja, North Iceland: Lateral flow revisited, Geochem. Geophys. Geosyst., 14, 2286–2309, doi:10.1002/ggge.20151

M.E. Hartley, T. Thordarson, J.G. Fitton and EIMF (2013), Oxygen isotopes in melt inclusions and glasses from the Askja volcanic system, North Iceland, Geochimica et Cosmochimica Acta, 123, 55–73. doi: 10.1016/j.gca.2013.09.008

Hartley, M. E., and T. Thordarson (2012), Formation of Öskjuvatn caldera at Askja, North Iceland: Mechanism of caldera collapse and implications for the lateral flow hypothesis, Journal of Volcanology and Geothermal Research, 227-228, 85-101. doi:10.1016/j.jvolgeores.2012.02.009

M. T. Gudmundsson, G. Larsen, Á. Höskuldsson and Á. G. Gylfason, 2008.  Volcanic hazards in Iceland, Jökull (58), 251-268.

Óladóttir, B.A., Larsen G. & Sigmarsson, O. Holocene volcanic activity at Grímsvötn, Bárdarbunga and Kverkfjöll subglacial centres beneath Vatnajökull, Iceland. Bulletin of Volcanology, 73, 1187-1208. doi: 10.1007/s00445-011-0461-4

Björnsdóttir, Þ. & Einarsson, P., 2013. Evidence of recent fault movements in the Tungnafellsjökull fissure swarm in the Central Volcanic Zone, Iceland. Jökull (63), 17-32.

Björnsson, H. & Einarsson, P., 1990. Volcanoes beneath Vatnajökull, Iceland: Evidence from radio echo-sounding, earthquakes and jökulhlaups. Jökull (40), 147-168.

Einarsson, P., 1991. Earthquakes and present-day tectonism in Iceland. Tectonophysics, 189, 261-279.

Thordarson, T., and G. Larsen, 2007. Volcanism in Iceland in historical time: Volcano types, eruption styles and eruptive history. Journal of Geodynamics, 43, p. 118-152.

Pagli, C., and F. Sigmundsson, 2008. Will present day glacier retreat increase volcanic activity? Stress induced by recent glacier retreat and its effect on magmatism at the Vatnajökull ice cap, Iceland. Geophys. Res. Lett., 35, L09304, doi:10.1029/2008GL033510.



Vulkanske gasser fra Bardarbunga…

Volcanic gas hazard

Wed, 09/03/2014 – 13:21 — rosa

Magma contains dissolved gases that are released into the atmosphere during eruptions. Gases are also released from magma that either remains below ground (for example, as an intrusion) or is rising towards the surface. In such cases, gases may escape continuously into the atmosphere from the soil, volcanic vents, fumaroles, and hydrothermal systems.
The major volcanic gases emitted from basaltic magma are H2O, CO2, SO2, H2, CO, H2S, HCl and HF. The most abundant gas is water vapor (H2O), followed by carbon dioxide (CO2) and sulfur dioxide (SO2).

Volcanic gas hazard (pdf file)

 



Nyt om Island…

Copyright: Institute of Earth Sciences

Bardarbunga 2014

For more detailed information on the Bárðarbunga event go to the IMO (Icelandic Met Office) webpage

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.

2. September 2014

Photomicrograph of silicate melt inclusions in plagioclase crystals picked from sample 11 erupted on 31st of August.


02.09.2014, 12:20 UTC – Conclusions of the Scientific Advisory Board of the Icelandic Civil Protection:

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.

A noticeable decrease in seismicity has occurred during the last 24 hours. The level of activity is approximately half of that during recent days. Since midnight today, around 300 earthquakes have occurred. At the same time yesterday, 01 September, around 500 earthquakes had been detected.
The rate of deformation at GPS sites closest to the dyke intrusion has decreased. Together with an overnight decrease in seismicity, this implies that magma inflow appears to match magma outflow at the eruption site.
The eruption has not created any ash-fall.
A white plume of steam and gas rises from the eruption on Holuhraun, reaching an elevation of about 4.5 km above sea level. Downwind, a volcanic cloud extends from the eruption site. Yesterday afternoon, a white cloud from the eruption extended 60 km to the north-north-east. In comparison to yesterday, more sulphur dioxide has been measured in the eruption cloud.
Sandstorms on the floodplain around the eruption site have contributed fine-grained particles to the eruption cloud. This was seen as a light-brown haze earlier today near to Egilsstaðir.
The eruptive fissure is about 1.5 km in length, positioned about 4.5 km from the ice margin of Dyngjujökull. At 14:00 UTC yesterday, the lava flow was 4.2 km2 in area. At 08:00 UTC the edge had extended 1.5 km to the east-south-east. The eruption continues, although there appears to have been a slight decrease in activity compared to yesterday. It remains unclear how the situation will develop. Four scenarios are still considered most likely:

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

Observations of tephra deposits from 29-08-2014 by the lava producing event at Holuhraun, North Iceland

Two very small tephra fall sectors are present on the west side of the fissure.

The first sector is comprised of fine-grained grey ash with origin at the southern part of the active fissure. This tephra fall rests on the surface of two fresh and westward trending lava flows surrounding the venting area on the southern end of the fissure. The deposit was distributed from about 150 m along the fissure and thickness of the fall deposit at the vents is 2 cm. 10 m to the west of the vents the thickness drops to 0.5 cm. Further away from the vents the deposit was eroded and remobilized. Thickness estimated to be less than mm in the area >20 m away from craters. Beneath the grey ash is a 0.3-0.4 cm thick lithic layer, comprised of angular and rounded lithics of approximate 0.1-0.2 cm in diameter, this lithic layer was only observed within 10m of the vent.

The second tephra sector is a red-brown ash fall observed close to the largest vent on the new fissure. The deposit reached up to 10 m from its vents and consists of red-oxidized and black juvenile fragments along with grains of plagioclase. The mean grain size of this deposit ranges from 0.2 cm at vent to 0.1 cm 10 m from vent. Water-escape features and dampness of the deposit indicates moist emplacement. Thickness at vent is 0.4-0.6 cm and 10 m west of the vent it has dropped to 0.2 cm.

Jónas Gudnason, Kate Gallegher, and Johanne Schmith.

 

New COSMO-SkyMED decending interferogram spanning the period 13 – 29 August 2014

COSMO-SkyMED descending wrapped interferogram spanning the period 13 – 29 August 2014. Each interferometric fringe corresponds to 15 millimeters of relative change in range from ground to satellite.  The highest fringe rate is observed closest to the subsurface dike causing the deformation. Decorrelation in the interferogram is caused by large amount of deformation at the surface, lava flows formed in an eruption between the acquisition of the images used, and surface change due to unstable sand.
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

31. August 2014
Daily status report 31. August 2014 – compiled by IMO (Icelandic Met Office) and IES (Institute of Earth Scienses) (pdf)

Bárðarbunga: 31.08.2014, 12:00 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:

·        A lava eruption started in Holuhraun shortly after 04 AM, on the same volcanic fissure, which erupted earlier this week. The fissure is estimated to be 1,5 km long. It was detected on Míla´s web-camera at 05:51 AM. Fewer earthquakes seem to follow the event than in the previous eruption, but more lava is being extruded.

·        At 07 AM the lava flow was around 1 km wide and 3 km long towards northeast. The thickness was estimated a few meters, the flow about 1000 m3 pr second.

·        Approximately 500 earthquakes were detected in the area and smaller than before. The strongest earthquake, M3.8 was in the Bárðarbunga caldera. Poor weather conditions prevail in the area, which makes detection of smaller earthquakes difficult.

·        GPS measurements show continued movements north of Dyngjujökull.

·        Gas emissions rise to a few hundred meters above the fissure.

·        Weather conditions make it difficult to follow the progression of the eruption, but scientists are in the area, using every opportunity to acquire information on gas and lava outflow.

·        Weather conditions do not allow overflight at this time. The opportunity to fly over the area will be assessed later today.

From the Icelandic Met Office:

The Aviation Colour Code for Bárðarbunga is at ‘red’ and the code for Askja at ‘yellow’.

 

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: Ármann Höskuldsson

 

An upgraded plot of Bárðarbunga seismicity and dike propagation based on revised earthquake locations from IMO, circle size represents earthquake magnitude. The three eruptions are marked by orange colored bars. Note how rapid dike propagation northwards coincides with the SE Bárðarbunga flank eruption whereas a slight decrease in dike propagation is associated with the first Holuhraun eruption.

Bryndís Brandsdóttir

 

30. August 2014

Bárðarbunga: 30.08.2014, 12:00 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:

·       Earthquake activity continues on a 15-km-long region of the dyke intrusion, extending both into the Dyngjujökull glacier and the region north of the ice margin. Earthquakes have not migrated northwards during the last two days. Seismicity remains high and, since midnight, about 700 earthquakes have been detected in the region.

·       The largest earthquakes since midnight include: (i) a magnitude 4.5 event on the northern side of the Bárðarbunga caldera at 02:35 UTC; (ii) a magnitude 4.2 earthquake in the same region at 06:18 UTC; and (iii) a magnitude 5.4 earthquake on the south-eastern edge of the Bárðarbunga caldera at 07:03 UTC. During the last two weeks, several earthquakes of similar size have occurred on the edge of the Bárðarbunga caldera. These earthquakes are interpreted as signs of stress changes in the region of the caldera.

·       Over 20 micro-earthquakes have been detected in the Askja region. It is thought that these earthquakes have occurred due to stress changes north of the dyke intrusion.

·       GPS measurements show continued horizontal movements north of Vatnajökull due to formation of the dyke intrusion on the northern edge of the ice-cap.

·       No unusual changes in the discharge or electrical conductivity of Jökulsá á Fjöllum have been detected. The same applies to other rivers draining from north-western Vatnajökull.

·       A sample of newly erupted lava was taken from Holuhraun yesterday; analysis is ongoing.

·       There are no indications that the intensity of the activity declining.

·       At this moment it is unclear how the situation will develop. However, four scenarios are 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 north of Dyngjujökull causing another eruption, possibly on a new fissure. Such an eruption could include lava flow and (or) explosive activity.

o   The intrusion reaches the surface and an eruption occurs again 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’.

29. August 2014

Bárðarbunga: 29.08.2014, 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:
• At 00:02 UTC signs of a lava eruption were detected on web camera images from Mila. The web-camera is located at Vaðalda, north-east of the eruption site.
• Around midnight, weak signs of increased tremor were apparent on IMO’s seismic stations near to the eruption site.
• At 00:20 UTC scientists in the field from the Icelandic Met Office, Institute of Earth Sciences and Cambridge University confirmed the location of the eruption.
• The eruption occurred on an old volcanic fissure on the Holuhraun lava field, about 5 km north of the Dyngjujökull ice margin. The active fissure was about 600 m in length.
• A small amount of lava drained from the fissure and by around 04:00 UTC, lava flow is thought to have stopped.
• According to seismic data and web-camera imagery, the eruption peaked between 00:40 and 01:00 UTC.
• At the beginning of the eruption, seismic activity decreased, although seismicity has since returned to levels observed in recent days.
• Aerial observations by the Icelandic Coastguard show that only steam is rising from the site of the lava eruption.
• There are no indications that the intensity of the activity declining.
• At this moment it is unclear how the situation will develop. However, three scenarios are considered most likely:
  • The migration of magma could stop, resulting in a gradual reduction in seismic activity and no further eruptions.
  • The dike could reach the Earth’s surface north of Dyngjujökull causing another eruption, possibly on a new fissure. Such an eruption could include lava flow and (or) explosive activity.
  • The intrusion reaches the surface and an eruption occurs again 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.
• Other scenarios cannot be excluded. For example, an eruption inside the Bárdarbunga caldera.
From the Icelandic Met Office:
At 10:00 UTC, IMO changed the Aviation Colour Code for Bárðarbunga to ‘orange’, signifying that significant emission of ash into the atmosphere is unlikely. The aviation colour-code for the Askja volcano remains at ‘yellow’.

An overview of Bárðarbunga seismicity and dike propagation, August 16th-28th – Bryndís Brandsdóttir

Revised earthquake locations from IMO, circle size represents earthquake magnitude. Dike propagation commences following termination of Kistufell activity. Advances in dike probation (marked by vertical lines) are related to large deflation events in Bárðarbunga.

29. August 2014 at 7:10 UTC

An eruption has started in Holuhraun north of Dyngjujökull at 00:02 this morning. An approximately 1 km long fissure (first estimate of scientists in the field) has opened, the eruption is purely effusive and no signs of explosive activity or ash emission has been detected so far. Based on volcanic tremor data, the eruption was strongest between 00:20 and around 02:00, peaking between 00:400 and 01:00. It has been decreasing until about 02:30 and is stabily active since.
Seismic activity has decreased as a result of the pressure release, however a significant amount of earthquakes is still detected in the magma dike, between the eruption site and south to about 5 km into Dyngjujökull. Strongest events last night were 3.8 in the caldera of Bárðarbunga at 04:37, as well as 2.9 at 05:39 and 3.5 at 06:38 in the dike. These earthquake are very closely monitored, but no significant change volcanic activity following these has been observed so far.

New COSMO-SkyMED ascending and decending interferograms

COSMO-SkyMED ascending interferogram spanning the period 11th August 2014 – 27th August 2014. Each fringe represents ~1.5 cm of displacement in the satellite’s line-of-sight.

COSMO-SkyMED descending interferogram spanning the period 10th August 2014 – 26th August 2014. Each fringe represents ~1.5 cm of displacement in the satellite’s line-of-sight.

 

Processing carried out using CSK Products, © ASI (Italian Space Agency) – 2014, delivered under an ASI license to use. COSMO-SkyMed images have been provided in the framework of the Geohazard Supersite Initiative.

Model of surface deformation, incorporating both GPS and satellite data, spanning the period 10th August 2014 – 27th August 2014. The vertical plane represents the location of the dike at depth (red colours show maximum opening). The model indicates that the eruption (red star) is coming from the patch with maximum opening (5m), right at the surface (dark red patch). Black dots show earthquakes during the same time period (since the start of unrest on the 16th August 2014) located by the Icelandic Met Office. Model processed by A.J.H.

Interferogram processing carried out using CSK Products, © ASI (Italian Space Agency) - 2014, delivered under an ASI license to use. COSMO-SkyMed images have been provided in the framework of the Geohazard Supersite Initiative.

29. August 2014

IMO has visual confirmation via scientists in the field and via webcam that a A fissure eruption (hraungos / sprungugos) has started north of Dyngjujökull (Holuhraun). Based on webcams and seismic data the eruption started at 00:02 (29/8/14).

No volcanic ash has been detected with the radar system at the moment. The wind field condition in the area are wind blowing toward NW at 12 m/s at 5 km altitude. Seismic eruption tremor is low indicating effusive eruption without significant explosive activity.

Satellite infrared images (Seviri 3,9 micron) confirm thermal anomaly at 00:38.

The color code at Bárðarbunga has been changed to red.

28. August 2014

Bárðarbunga: 28.08.2014, 12:00 UTC

Conclusions of the Scientific Advisory Board of the Icelandic Civil Protection

Scientists from the Icelandic Meteorological Office and the Institute of Earth Sciences, together with representatives of the Civil Protection in Iceland, met today to discuss the on-going unrest at the Bárðarbunga volcano.

This morning, there was a flight over the Bárðarbunga area and the surface of the glacier was surveyed. No changes to the ice crevasses southeast of Bárðarbunga, that were seen yesterday evening, were observed. These crevasses were likely formed due to melting at the ice bottom.

The depressions have been located southeast of the Bárðarbunga caldera, in all likelihood within the water divide of the river Jökulsá á Fjöllum. There are three circular crevasse formations, about 5 km in total length. The ice thickness in the area is 400-600 m.

The water level in Grímsvötn Lake has been surveyed and has likely risen by about 5-10 m in the last days, which corresponds to an addition of 10-30 million m3 of water in the lake. A slight increase in conductivity in Köldukvísl River was measured this morning, but the cause is yet unknown. No change has been measured in the Hágöngulón lagoon, Jökulsá River and Skjálfandi River. It is assumed, that the water from the cauldron has flowed into the Grímsvötn Lake or the river Jökulsá á Fjöllum.

The seismic activity is similar to that of the last days. Around midnight, three earthquakes of magnitude around 4 were recorded and one of magnitude 5 at 08:13 this morning, all located within the Bárðarbunga caldera.

Shortly before 08:00 this morning, there was a slight increase in seismic activity in Askja volcano. Changes in the stress field due to expansion caused by the dyke have an effect on the Askja area.

Since yesterday, the length of the dyke under Dyngjujökull has increased by 1-1.5 km to the north, which is considerably less than in the last days. The dyke has now reached the fissure system of the Askja volcano and GPS measurements indicate that the area there is greatly affected.

The conclusions from the meeting of the Scientific Advisory Board of the Icelandic Civil Protection will continue to be published at around noon, after the meeting, if necessary.

From the Icelandic Met Office: The Aviation Colour Code remains at the ‘orange’ level for Bárðarbunga. The Aviation Colour code is raised to ‘yellow’ level for Askja.

 

New page showing cumulative displacements at cGPS stations near Bárðarbunga and earthquakes

 

 

27. August 2014

Bárðarbunga: 27.08.2014, 11:50 UTC – Conclusions of the Scientific Advisory Board of the Icelandic Civil Protection
Scientists from the Icelandic Meteorological Office and the Institute of Earth Sciences, together with representatives of the Civil Protection in Iceland, met today to discuss the on-going unrest at the Bárðarbunga volcano.
These are the conclusions of the meeting: • Intense seismi…city continues. Over 700 earthquakes have been recorded since midnight. Earthquakes are occurring mostly beyond the edge of the Dyngjujökull glacier and the intrusion itself has migrated about 1 km northwards since yesterday. • At 00:16 UTC today, a magnitude 5.3 earthquake occurred in the caldera of Bárðarbunga. At 02:50 UTC, another similar-sized earthquake (magnitude 5.2) took place in the same region. • At 01:52 UTC, a magnitude 4.5 earthquake was detected on the eastern side of the Askja volcano. This was followed by a few micro-earthquakes in the same area. • The dyke intrusion beneath Dyngjujökull is thought to be about 40 km in length. • Modelling of GPS data indicates that about 20 million cubic metres of magma have been added to the volume of the intrusion in the last 24 hours. • Modelling results suggest that the dyke intrusion is causing stress changes over a large area, including the region to the north of the dyke’s extent; this could account for the increased seismicity at Askja volcano. • There are no indications that the intensity of the activity declining. • From today, the afternoon status report will no longer be produced. However, if the situation escalates (i.e. imminent signs of an eruption), daily status reports will be reintroduced. The results of the scientific advisory board (this factsheet) will continue to be distributed daily at around midday.
From the Icelandic Met Office: The Aviation Colour Code remains at the ‘orange’ level for Bárðarbunga.

26. August 2014

Daily status report 26. August 2014 – compiled by IMO (Icelandic Met Office) and IES (Institute of Earth Scienses) (pdf)

26. August 2014 kl. 11:50 – 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 Advisory Board

The following points were the conclusion at a meeting of the Advisory Board today:

  • Intense seismicity continues. Over 500 events have been recorded since midnight.
  • Seismicity continues to migrate northward. Seismicity is now concentrated on the 10 km long tip of the dike extending 5 km beyond the edge of the Dyngjujökull glacier.
  • At 01:26 this morning an earthquake of magnitude 5,7 was observed beneath the Bárðarbunga caldera.
  • The dyke beneath Dyngjujökull is now thought to be close to 40 km long. Modelling of GPS data indicates that about 50 million cubic meters of magma have added to the volume in the last 24 hours.
  • There are no indications that the intensity of the activity declining. The following three scenarios are still considered most likely:
    • The migration of magma could stop, accompanied by a gradual reduction in seismic activity.
    • The dike could reach the surface of the crust, starting an eruption. In this scenario, it is most likely that the eruption would be near the northern tip of the dyke. This would most likely produce an effusive lava eruption with limited explosive, ash-producing activity.
    • An alternate scenario would be the dyke reaching the surface where a significant part, or all, of the fissure is beneath the glacier. This would most likely produce a flood in Jökulsá á Fjöllum and perhaps explosive, ash-producing activity.
  • Other scenarios cannot be excluded. For example, an eruption inside the Bárðarbunga caldera is possible but presently considered to be less likely.

From the Icelandic Met Office: The Aviation Color Code remains at the ‘orange’ level.

25. August 2014

Daily status report 25. August 2014 – compiled by IMO (Icelandic Met Office) and IES (Institute of Earth Scienses) (pdf)

25.08.2014 11:00 – 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 Advisory Board

The following was presented at a meeting of the Advisory Board at 10 am today:

  • Intense seismicity continues. Over 700 events have been recorded since midnight.
  • Seismicity continues to migrate northward. Seismicity is now concentrated on the 10 km long tip of the dike extending 5 km beyond the edge of the Dyngjujökull glacier.
  • At 20:39 last night an earthquake of magnitude ~5 was observed beneath the Bárðarbunga caldera. Since then earthquakes in the caldera have been smaller.
  • The dike beneath Dyngjujökull is now thought to be close to 35 km long. Modelling of GPS data indicates that it contains about 300 million cubic meters of magma.
  • Additional stations for continuous GPS monitoring will be installed north of Vonarskarð and on Urðarháls within a few days.
  • There are no indications that the intensity of the activity declining.
  • Currently, three scenarios are considered most likely:
  • The migration of magma could stop, attended by a gradual reduction in seismic activity.
  • The dike could reach the surface of the crust, starting an eruption. In this scenario, it is most likely that the eruption would be near the northern tip of the dike. This would most likely produce an effusive lava eruption with limited explosive, ash-producing activity.
  • An alternate scenario would be the dike reaching the surface where a significant part, or all, of the fissure is beneath the glacier. This would most likely produce a flood in Jökulsá á Fjöllum and perhaps explosive, ash-producing activity.
  • Other scenarios cannot be excluded. For example, an eruption inside the Bárdarbunga caldera is possible but presently considered to be less likely.

24. August 2014

Daily status report 24. August 2014 – compiled by IMO (Icelandic Met Office) and IES (Institute of Earth Scienses) (pdf)

23. August 2014

Bárðarbunga – Dyngjujökull – aircraft observations on 23 August


Detailed observations from TF-SIF, the Coast Guard Dash 9 were performed in the afternoon of the 23rd of August.  The observations revealed that no signs of an ongoing eruption could be detected and it is concluded that a subglacial eruption did not happen.  Increased low frequency tremor observed on that day must therefore have a different explanation.

The SAR-radar images obtained by the aircraft in the afternoon of 23 August show that no changes have occurred, neither subsidence, or unusal discharge of rivers.

Experience from subglacial eruptions in the past suggests the following:

·       Large scale melting of ice occurs if an eruption takes place beneath a glacier.  Even very small eruptions (like the eruption at Fimmvorðuháls that preceded the Eyjafjallajökull eruption in 2010) if they had taken place under ice, would melt of the order of 100 cubic meters per second of ice and cause notable increase in discharge in glacial rivers.

·       In most cases meltwater will flow away from the eruption site towards the edge of the glacier.  If an eruption occurs in late summer the drainage system at the bottom of the glacier is well developed.  This means that water will drain fast to the edge of the glacier.  For example, if an eruption site is located under ice, 5-10 km from the edge of the glacier it is expected that meltwater will reach the edge in about an hour.

·       The time it takes an eruption to melt its way to the surface is strongly dependent on the ice thickness.  As an example, the moderate sized eruption of Grímsvötn in 2004, melted through 150 m of ice in about one hour while the more powerful Gjálp eruption in 1996 took 31 hours to melt through 600 m of ice.

·       The above implies that the meltwater from an eruption beginning under e.g. 500 m of ice in Dyngjujökull would emerge from the glacier several hours before the eruption melts through the glacier sparking off an explosive eruption because of magma-water interaction.

Magnús Tumi Guðmundsson
Further material:

Hazard due to eruptions, including subglacial ones (Jökull 2008): https://notendur.hi.is//~mtg/pdf/2008Jokull58_MTGetal_volchaz.pdf On the volcano-ice interaction in the Gjálp eruption: https://notendur.hi.is//~mtg/pdf/1997Nature_MTG_FS_HB.pdf and https://notendur.hi.is//~mtg/pdf/2003BullVolc66_MTGetal_Gjalp.pdf And on eruptions in glaciers in general: https://notendur.hi.is//~mtg/pdf/2005SubglacVolcAct_MTG-DQS.pdf https://notendur.hi.is//~mtg/pdf/2003GeopMono140_MTG_magma-ice-water.pdf

Daily status report 23. August 2014 – compiled by IMO (Icelandic Met Office) and IES (Institute of Earth Scienses) (pdf)

23.08.2014, 20:30 UTC – Bárðarbunga

Information from Icelandic Met Office (IMO)

  • At 11:20 UTC today, seismic tremor measurements gave a strong indication that an eruption beneath Dyngjujökull was occurring. Tremor levels decreased during the afternoon, although intense earthquake activity continues.
  • At 14:00 UTC, an over-flight was made to Bárðarbunga by the Icelandic Coastguard with scientists from the Icelandic Meteorological Office and the University of Iceland, in addition to a representative from the National Commissioner of the Icelandic Police.
  • The over-flight covered the north-western region of the Vatnajökull ice-cap in clear conditions. Both visual observations and radar measurements confirmed no significant changes on the surface of Vatnajökull. Likewise, there were no signs of floodwater draining from the ice margin.
  • During three hours of aerial surveillance, there were no obvious signs of volcanic activity.
  • In light of the intense, ongoing earthquake activity and crustal deformation at Bárðarbunga, the Icelandic Meteorological Office has decided that the aviation colour-code should remain ‘red’, signifying that an eruption is either imminent or in progress. The situation will be reassessed tomorrow morning.

23rd August 2014 14:10 – a small eruption under Dyngjujökull?

Information from Icelandic Met Office (IMO)

  • The Icelandic Coast Guard airplane TF-SIF is flying over the area with representatives from the Civil Protection and experts from the Icelandic Met Office and the Institute of Earth Sciences. Data from the equipment on board is expected later today.
  • Data from radars and web-cameras is being received, showing no signs of changes at the surface.
  • The estimate is that 150-400 meters of ice is above the area.
  • The aviation color code for the Bárðarbunga volcano has been changed from orange to red.
  • Some minutes ago (14:04), an earthquake occurred, estimated 4.5 in magnitude.

22. August 2014

Daily status report 22. August 2014 – compiled by IMO (Icelandic Met Office) and IES (Institute of Earth Scienses) (pdf)

GPS time series around Bárðabunga, including recently installed continuous GPS station GSIG in Kverkfjöll


GPS time series for the last 3 months http://strokkur.raunvis.hi.is/gps/DYNC_3mrap.png http://strokkur.raunvis.hi.is/gps/HAFS_3mrap.png http://strokkur.raunvis.hi.is/gps/GFUM_3mrap.png http://strokkur.raunvis.hi.is/gps/VONC_3mrap.png http://strokkur.raunvis.hi.is/gps/GSIG_3mrap.png

1 year GPS time series http://strokkur.raunvis.hi.is/gps/DYNC_rap.png http://strokkur.raunvis.hi.is/gps/HAFS_rap.png http://strokkur.raunvis.hi.is/gps/GFUM_rap.png http://strokkur.raunvis.hi.is/gps/VONC_rap.png http://strokkur.raunvis.hi.is/gps/GSIG_rap.png

Extended time series http://strokkur.raunvis.hi.is/gps/DYNC_08.png http://strokkur.raunvis.hi.is/gps/HAFS_08.png http://strokkur.raunvis.hi.is/gps/GFUM_08.png http://strokkur.raunvis.hi.is/gps/VONC_08.png

21. August 2014

Daily status report 21. August 2014 – compiled by IMO (Icelandic Met Office) and IES (Institute of Earth Scienses) (pdf)

20. August 2014

Daily status report 20. August 2014 – compiled by IMO (Icelandic Met Office) and IES (Institute of Earth Scienses) (pdf)

Since the start of the earthquake swarm, precise continuous GPS stations located in the vicinity of the Bárðarbunga central volcano have shown movements which indicate that magma is propagating in the crust.  During the period between 8 am on the 15th of August and 4 pm on the 18th of August a GPS station on Dyngjuháls moved 5,4 cm towards the northwest and a GPS station near Grímsvötn moved 1,8 cm towards the south.

The map shows locations of earthquakes detected by the SIL network of the Icelandic Meteorological Office.  Movements on continuous GPS stations are shown as blue arrows, the continuous stations are run in cooperation between the Institute of Earth Sciences at the University of Iceland and by the Icelandic Meteorological Office.  Fractures and eruptive fissures in the area are denoted by yellow and red lines respectively.

The orange arrows show a model on how the GPS stations could be moving if a dike was propagating (see thick red line on map), and magma was draining away from the Bárðarbunga magma chamber („Mogi center“).  It has to be mentioned, however, that this model is only one of several models that can explain the movements seen on the GPS stations.

——-
Possible model of the dike intrusion:

Length of dike: 20 km

Height of dike: 2,1 km

Opening of dike: 1,6 m

Depth to the dike: 3 km

Volume of dike: 80-90 million cubic meters

Strike = 47,51, dip 90 (predefined)

Depth to Mogi source: 1 km

Volume change of Mogi source:

-10 til -30 million cubic meters

——-

References

GPS data – Institute of Earth Sciences, University of Iceland and the Icelandic Meteorological Office

Model calculations:  Elías Rafn Heimisson, Freysteinn Sigmundsson

Earthquakes: Icelandic Meteorological Office (part of the earthquakes have not been reviewed).

Fractures near Tungnafellsjökull: Þórhildur Björnsdóttir and

Páll Einarsson (Jökull, 2013).

Fractures and eruptive fissures in the Northern Volcanic Zone: Ásta Rut Hjartardóttir

and Páll Einarsson (2012), Ásta Rut Hjartardóttir (2013).

Background:  IS50 database of the National Land Survey of Iceland.

19. August 2014

3m http://strokkur.raunvis.hi.is/gps/DYNC_3mrap.png http://strokkur.raunvis.hi.is/gps/HAFS_3mrap.png http://strokkur.raunvis.hi.is/gps/GFUM_3mrap.png http://strokkur.raunvis.hi.is/gps/VONC_3mrap.png 1yr http://strokkur.raunvis.hi.is/gps/DYNC_rap.png http://strokkur.raunvis.hi.is/gps/HAFS_rap.png http://strokkur.raunvis.hi.is/gps/GFUM_rap.png http://strokkur.raunvis.hi.is/gps/VONC_rap.png long http://strokkur.raunvis.hi.is/gps/DYNC_08.png http://strokkur.raunvis.hi.is/gps/HAFS_08.png http://strokkur.raunvis.hi.is/gps/GFUM_08.png http://strokkur.raunvis.hi.is/gps/VONC_08.png

18. August 2014

Melissa Pfeffer posted this message on Basecamp:

Bárðarbunga aviation color code changed to orange

The intense seismic activity that started on 16 of August at Bárðarbunga persists. Very strong indications of ongoing magma movement, in connection with dyke intrusion, is corroborated by GPS measurements. There are currently two swarms: one to the E of Bárðarbunga caldera and one at the edge of Dyngjajökull just E of Kistufell. At 2.37 am on the 18th a strong earthquake (M4) was located in the Kistufell swarm. This is the strongest earthquake measured in the region since 1996. As evidence of magma movement shallower than 10 km implies increased potential of a volcanic eruption, we are moving the Bárðarbunga aviation color code to orange (after a reevaluation of the events in the last days).

Presently there are no signs of eruption, but we cannot exclude that the current activity will result in an explosive subglacial eruption, leading to an outburst flood (jökulhlaup) and ash emission. The situation is monitored closely.

 

The update map is available at:

http://en.vedur.is/earthquakes-and-volcanism/volcanic-eruptions/

17. August 2014

An intense seismic swarm is currently taking place under the eastern part of Bárðarbunga. Between 03:04 and 13:00 on August 16th a total of 189 earthquakes occurred (max. M2.9).  The seismic swarm continues and continuous GPS stations have detected deformation that confirm magma movements associated with intrusive activity. No indications of surface magma extrusion beneath the ice cap have been observed. If the activity progresses towards an eruption, a scenario could involve a subglacial, or partly subglacial eruption, at the northwestern part or edge of Vatnajökull, with a jökulhlaup in the Jökulsá á Fjöllum river towards the north.

This is the largest seismic swarm seen in Bárðarbunga since the end of September 1996, in the days leading to the Gjálp eruption.  The area is covered by Vatnajökull and the ice thickness varies from 100-200 at  the caldera rims of Bárðarbunga to over 800 m within the Bárðarbunga caldera. IMO, IES and Civil Protection are monitoring the situation – the seismic activity can be observed at www.vedur.is.

A direct link to the Vatnajökull seismic map is: http://www.vedur.is/skjalftar-og-eldgos/jardskjalftar/vatnajokull/#view=map

Publications:

Hartley, M. E., and T. Thordarson (2013), The 1874–1876 volcano-tectonic episode at Askja, North Iceland: Lateral flow revisited, Geochem. Geophys. Geosyst., 14, 2286–2309, doi:10.1002/ggge.20151

M.E. Hartley, T. Thordarson, J.G. Fitton and EIMF (2013), Oxygen isotopes in melt inclusions and glasses from the Askja volcanic system, North Iceland, Geochimica et Cosmochimica Acta, 123, 55–73. doi: 10.1016/j.gca.2013.09.008

Hartley, M. E., and T. Thordarson (2012), Formation of Öskjuvatn caldera at Askja, North Iceland: Mechanism of caldera collapse and implications for the lateral flow hypothesis, Journal of Volcanology and Geothermal Research, 227-228, 85-101. doi:10.1016/j.jvolgeores.2012.02.009

M. T. Gudmundsson, G. Larsen, Á. Höskuldsson and Á. G. Gylfason, 2008.  Volcanic hazards in Iceland, Jökull (58), 251-268.

Óladóttir, B.A., Larsen G. & Sigmarsson, O. Holocene volcanic activity at Grímsvötn, Bárdarbunga and Kverkfjöll subglacial centres beneath Vatnajökull, Iceland. Bulletin of Volcanology, 73, 1187-1208. doi: 10.1007/s00445-011-0461-4

Björnsdóttir, Þ. & Einarsson, P., 2013. Evidence of recent fault movements in the Tungnafellsjökull fissure swarm in the Central Volcanic Zone, Iceland. Jökull (63), 17-32.

Björnsson, H. & Einarsson, P., 1990. Volcanoes beneath Vatnajökull, Iceland: Evidence from radio echo-sounding, earthquakes and jökulhlaups. Jökull (40), 147-168.

Einarsson, P., 1991. Earthquakes and present-day tectonism in Iceland. Tectonophysics, 189, 261-279.

Thordarson, T., and G. Larsen, 2007. Volcanism in Iceland in historical time: Volcano types, eruption styles and eruptive history. Journal of Geodynamics, 43, p. 118-152.

Pagli, C., and F. Sigmundsson, 2008. Will present day glacier retreat increase volcanic activity? Stress induced by recent glacier retreat and its effect on magmatism at the Vatnajökull ice cap, Iceland. Geophys. Res. Lett., 35, L09304, doi:10.1029/2008GL033510.