Lava field now approx. 85 square km
Update Mon 19 Jan 15:04
Landsat 8 image of the Holuhraun lava field on 16 Jan 2015
Eruption continues with little changes
Update Mon 12 Jan 09:50
It has crossed the track Dyngjufjallaleið and stretched onto the older lava of Þorvaldshraun.
Lava is mainly flowing through a closed channel to the eastern edge of the lava field, about 15 km from the crater. Another tube system is transporting lava to the northern part.
Seismicity under the Bardarbunga central volcano's caldera remains strong. Subsidence of the caldera continues as well, at approx. 25 cm per day.
Eruption continues with little changes
Update Sat 03 Jan 10:37
Map of the Nornahraun lava field as of 29 Dec 2014 (Univ. Iceland)
The lava field is now well over 82 square km large, a mapping from 29 Dec. shows.
Seismic activity remains concentrated around the summit caldera of Bardarbunga central volcano, while it is very low beneath the erupting dyke - magma has an open conduit towards the surface.
Eruptino continues, but seismic activity decreases under caldera
Update Sat 27 Dec 15:59
Map of the Nornahraun lava field as of 24 Dec 2014 (Univ. Iceland)
Subsidence and earthquakes at Bardarbunga caldera (IMO)
Seismic activity under the caldera has been slowly decreasing overall as well.
However, the decreasing trend is very weak and the eruption could still continue for many months, or take a new, unexpected evolution at any time. The future, or probably 2015 will tell!
Update Fri 19 Dec 10:01
View of the eruption at Holuhraun this morning (MILA webcam)
Updated map of the lava flow field at Holuhraun (IMO)
Earthquake activity remains significant under the caldera, which continues to subside. Occasional quakes reach magnitudes above 5.
Lava field now more than 77 squake km, no end of eruption in sight
Update Fri 12 Dec 11:37
Landsat 8 image of the lava field at Holuhraun yesterday
A sea of lava at the eruption seen during an overflight on 8 Dec (Univ. Iceland)
Active breakout with lava advancing over snow (Univ. Iceland)
Active breakouts are located on the northern margin of the lava field, now called "Nornahraun".
Earthquake activity under the central volcano remains elevated, but over the past weeks, earthquakes larger than magnitude 4 have become more rare. Recent geochemical studies of the lava show that it seems to rise directly from a source at 9-20 km depth, i.e. is generated by decompressing mantle material.
Evolution and comparison of the Nornahraun lava field
Update Fri 12 Dec 11:46The Icelandic Met Office (IMO) published two great graphics showing the gradual evolution of the Holuhraun (or now called Nornahraun) lava flow field and compares it with the two largest lava fields erupted on Iceland in historic times, Laki in 1783 and Eldgjá in 934 AD. Even though it is the largest eruption in more than 150 years on Iceland, it still is much much smaller than those two.
Evolution of the lava flow field at Holuhraun (IMO)
Comparison of the Nornahraun lava flow field with the two largest historic ones on Iceland (IMO)
Eruption shows slowly decreasing trend
Update Fri 05 Dec 16:06
It is too early to predict an end of the eruption, which already has created the largest lava flow on earth since the massive 1783 Laki fissure eruption - only 50 km to the south and likely also fed by the Bardarbunga volcanic system.
New video of Holuhraun lavalake in snowy surroundings
Norðurflug helicopter company took advantage of the sunny and blue-skied weather yesterday to undertake a flight to the Holuhraun eruption site. One of their pilots, Gísli Gíslason, captured the beautiful scene they saw there in the video below.
The narrow, elongated lava lake that formed after weeks of fountaining is still glowing hot and bubbles away. Fresh snow partially blankets the cold surface of the lake's outer wall (constructed from a row of interconnected cinder cones). On those parts of the lava field that are still hot, however, the snow has molten - creating a dramatic contrast between the black lava and the snowy white surroundings.
Update Wed 03 Dec 18:26
The eruption continues with little changes. While most of the lava now remains on top of the already emplaced lava field, more than 75 square km large, several lateral outbreaks are active as well.
The most active one, to the north, has advanced more than 450 m in a single day.
Seismic activity remains high under the volcano - yesterday, 2 earthquakes above magnitude 2 occurred under Bárðarbunga. No significant earthquake activity occurs under the erupting dyke, suggesting the situation is stable.
Spectacular video of eruption
Update Tue 02 Dec 15:32
Snapshot from embedded video showing the boiling lava lake at the vent in Holuhraun
Eruption continues with little changes
Update Sun 30 Nov 15:42No apparent changes have occurred in the ongoing eruption. Earthquake activity under the Bardarbunga caldera has been a bit higher today than during the past days. 5 quakes of magnitudes 4.1-4.6 occurred today.
Seismic activity under the eruptive dyke has been very low.
Lava fall in Holuhraun’s growing lava field
Update Sat 29 Nov 11:46
Two night time images of lava falls cascading down from the edge of the new lava field. Photo:University of Iceland.
Crater and eruption column seen from hills southwest of the eruption site on 26 November 2014. Photo: Morten S. Riishuus.
The intensity of the eruption declined so that the present amount of emitted lava is only a quarter of what it was at the eruption’s most intense phase. But according to Ármann Höskuldsson, volcanologist at the University of Iceland Earth Science Institute, there are no indications that the volcanic activity will stop anytime soon. He points out that it remains a very intense eruption despite the recent (temporarily?) weakening of its activity. Scientists observed fluctuations in the eruption plume last week due to sporadic emission of powerful lava jets. The lava flow discharge pulsated accordingly.
The exact amount of magma flowing from the Bárðarbunga magma chamber through the intrusive dike below the Vatnajökull glacier and eventually erupting in Holuhraun is presently unclear. The Icelandic Broadcasting Service (RUV) reports it to be 130 cubic metres asecond, whereas the newspaper Morgunblaðið (mbli.is) estipmates it to be between 60 and 100 cubic metres per second.
The area continues to be very seismically active with every day a few earthquakes larger than M = 3 at the Bárðarbunga caldera and weaker trembling around the dike intrusion (Icelandic Met Office).
Eruption continues, fluctuating lava supply rates
Update Tue 25 Nov 15:58
Earthquakes and subsidence of the Bardarbunga caldera since 12 Sep (Icelandic Met Office)
It is thought that most of the magma comes from decompressing mantle material at approx. 10 km depth, i.e. directly from the Icelandic hot spot. The observed fluctuations could (but not necessarily does) mean that the magma supply has starting to decrease overall and/or that the dyke started to close up.
Earthquake activity under the caldera remains strong with frequent quakes in the magnitude 3-4 and occasional ones of magnitudes 5-5.4.
Subsidence of the caldera continues with little changes and amounts to 25 meters since 12 Sep.
Eruption evolved from fierce fountains to boiling lava lake
Update Mon 17 Nov 11:00stunning video recently shot by Jon Gustafson.
Meanwhile, both subsidence of the Bárðarbunga caldera and seismic activity continue at much the same rates as during the last weeks. The caldera floor sunk another meter over the past 48 h. Most earthquakes cluster at the northern edge of the caldera and are occasionally of magnitude 4 or higher. Seismic activity in the dyke intrusion thought to feed the Holuhraun eruption remains low. As long as the Holuhraun fissure eruption remains active it releases the pressure below the Bárðarbunga caldera. If the Baugur crater would however get ‘obstructed’ whilst magma continues to well up, the pressure is likely to increase as magma searches for another eruption location. Regardless of what happens next, this eruption is record-breaking as it already emitted an impressive volume of more than 1 cubic kilometer of lava. This makes it the second largest effusive eruption in Iceland since the 18th century. Number one is the 1783-1784 Laki eruption which gave rise to a staggering 14 cubic kilometer of erupted lava.
Another volcanic phenomena for which the current Holuhraun eruption is only outdone by the Laki eruption is the quantity of emitted sulphur dioxide gas. This pollution keeps troubling parts of Iceland, mainly in the east, as 40 - 60.000 tonnes of sulphur dioxide are released into the air every day. The sulphur dioxide gas can transform to sulphuric acid and give rise to ‘acid rain’. Rainwater has been monitored all over Iceland since the early stages of the eruption. Measurements show that for the moment about 40% of the Icelandic rain is polluted, but less than 1% of this acid rain has distinctly low pH values.
Although air pollution from the Laki eruption killed about half of the farm animals in Iceland and triggered the failure of crops due to a global climate change, the Holuhraun eruption is not yet of the size to cause a similar scenario.
- Icelandic Met Office
- Icelandic National Broadcasting Service RUV
Continuing eruption formed a 70 km² lava flow and caused 44 m of caldera subsidence since its onset on August 31
Update Sun 09 Nov 22:48The volcanic eruption at Holuhraun gives no signs of weakening and continues to eject an impressive lava fountain from the central Baugur crater at a rate similar to the past few weeks. This record-breaking eruption started on the 31st of August 2014 and formed a more than 17 km long lava flow. Using the successive outlines of this lava flow as drawn on a radar image from the Icelandic Coast Guard, researchers from the Institute of Earth Sciences estimated that by now the lava has covered an area of 70 km².
Subsidence of the glacier surface above the Bárðarbunga caldera is also still going on. This vertical displacement is monitored by near real time presentation of data from a GPS station that was mounted in the centre of the caldera on September 11. There was a technical problem that prohibited transmission of these GPS data on the 8th of November, but this has been fixed. Comparison of the vertical location of this GPS station before and after the ca. 24 h communication problem shows subsidence of up to half a meter in a single day. The total subsidence recorded at Bárðarbunga caldera since 12 September is 21 m and based on earlier GPS data the total subsidence since the onset of this eruption is at least 44 m.
The area’s seismic activity is also continuing at a similar intensity. On November 7 there was a M 5.4 earthquake at the northeastern rim of the caldera and this was the first earthquake over magnitude 5 since the 2nd of November. Since then, 15 earthquakes between magnitude 4 and 5 occurred, as well as quite a few between M 3 and M 4. Lower seismic activity is also observed at the intrusion, the largest earth quake of which was of magnitude 2.5.
All information and figures from the Icelandic Met Office
Eruption has produced over 1 cubic km of lava
Update Thu 06 Nov 14:01
Webcam view of the eruption this afternoon (Mila webcam)
The depression in the ice above the caldera continues to deepen, likely a combined result of increased melting due to increased geothermal heat flow and the continuing subsidence of the caldera itself.
Eruption continues with little changes
Update Wed 05 Nov 05:02The fissure eruption at the Holuhraun plain continues with similar intensity as during the past weeks. Earthquake activity under the caldera, which continues to subside, remains intense with many daily earthquakes in the magnitude 4-5 range.
Eruption continues with no changes
Update Thu 30 Oct 03:34
View of the eruption this morning (Mila webcam)
Gas plumes from the eruptino seen during a surveillance flight 28 Oct (IMO)
Earthquakes continue to be frequent under the central volcano's caldera.
Eruption and earthquakes continue
Update Tue 28 Oct 10:30No significant changes have occurred. The fissure eruption in Holuhraun continues with similar intensity as during the past weeks.
About 80 earthquakes have been located in the Bárðarbunga area past 24 hours. Two quakes were over magnitude 5 in the northern caldera rim this morning, one M5.0 at 04:54 and the other M5.1 at 06:04. Additionally, few quakes over magnitude 4 have been observed, but manual processing of these is not finished. Over ten quakes were located in the northern part of the dike intrusion. (IMO)
Cauldron deepens above volcano
Update Mon 27 Oct 15:49According to the latest information from IMO, geothermal heat is increasing in Bardarbunga volcano, which could indicate that an eruption at this location is becoming more likely.
An ice cauldron in the southeast corner of Bardarbunga has deepened about 25 meters over a one month period. The depression is probably a result of the continuing subsidence of the caldera.
Eruption continues, magnitude 5.3 earthquake
Update Mon 27 Oct 10:44The eruption continues with no significant changes.
Earthquakes continue to be intense under the Bárðarbunga caldera. The largest today was a magnitude 5.3 event at 01:05 local time under the southwestern rim.
Two quakes over 4 occurred at the caldera, an M4.6 at 17:34 yesterday and an M4.3 at 05:48 this morning, as well as a few over 3 in size. A dozen earthquakes were detected in the dike, all small.
Continuing eruption, increasing earthquakes at Bárdarbunga
Update Sat 25 Oct 15:25The eruption seems to continue with no changes, but there were no visual observations today. IMO writes:
"Seismic activity on the Bárðarbunga caldera rim continues at comparably high rates as in recent days. Activity in the dyke intrusion was rather low during the last 26 hours since the last report, seismicity around Herðubreið has slightly decreased.
"Approximately 110 earthquakes have been detected around the Bárðarbunga caldera. Strongest events were M5.2 today at 01:48 on the northern caldera rim and M5.0 yesterday at 10:23 on the north-eastern rim. Additionally, seven earthquakes were in the range of M4.0-4.9 and a dozen M3.0-3.9.
"Around 25 events have been detected in the northern part of the dyke intrusion, all below M1.5. About 20 earthquakes were detected around Herðubreið, none of them exceeded M2.0. No visual observation of the eruption so far today."
Eruption continues with large lava flows, increasing seismic activity at caldera
Update Fri 24 Oct 15:01The volcanic eruption in Holuhraun continues at similar rate, and has now been going on for more than 50 days.
The erupted lava flow volume approaches 1 cubic kilometers and the lava flows now cover over 63 square km.
A large lava lake above the central section of the fissure vent has formed and feeds a wide river of lava.
Seismic activity in Bardarbunga continues to be strong, and has somewhat increased over the past days. More than 50 quakes above magnitude 3 have occurred in the caldera during the past 2 days. At least 15 were larger than magnitude 4, the biggest being two 4.8 quakes at 13:21 on Wednesday and at 13:07 yesterday.
At the dyke, smaller earthquakes continue as well at reduced rate.
Subsidence of the Bardarbunga caldera continues at remarkably steady linear pace of approx. 50 cm per day.
No other significant changes have been detected.
Earthquakes today under Bárdarbunga volcano (IMO)
Depth vs time of recent earthquakes under Bárdarbunga
Subsidence of the Bardarbunga caldera since 12 Sep (IMO)
Eruption continues, increased earthquakes under caldera
Update Thu 16 Oct 16:42
The eruption continues from the Holuhraun fissure with an amazing lava output at approx. 350 cubic meters per second. A large lava pond has formed over the merged main craters on the central part of the fissure, from where a river of lava flows into the plain.
Earthquakes have increased under the Bardarbunga caldera, which could be a sign that something is about to change.
The Icelandic Met office' recent updates writes:
"During the last 24 hours, about 70 earthquakes have been detected at Bárðarbunga and a dozen in the northern part of the dike. This is somewhat less activity than 24 hours earlier. Two quakes over five in magnitude occurred at the northern caldera rim; an M5.4 at 11:16 yesterday and an M5.0 in the early hours of the morning, at 03:14 today. One earthquake M4.2 occurred later this morning, at 09:25, in a similar location.
Observations of deep thudding sounds were received yesterday while the large earthquake occurred, possibly as a consequence thereof. Scientist went to Askja yesterday but found no signs of a rockfall, which could have caused the noises. Possibly the sounds were from jet aircrafts, passing at the same time." (IMO)
15 Oct update
" there is an increase in the number of detected earthquakes in the Bárðarbunga area. Calm weather recently, resulting in better detection of small earthquakes, is hardly enough to explain this increase anymore and probably this increase is real.
During the last 24 hours, almost 130 earthquakes have been detected at Bárðabunga and about 30 in the northern part of the dike. No quakes above 5 in magnitude have been detected since 12 October, but five quakes yesterday were between 4.5 and 4.8. The eruption was clearly visible on webcams from midnight until almost 8 o‘clock this morning." (IMO)
eruption continues with little changes
Update Mon 13 Oct 17:18
Updated map of the lava flows as of 9 Oct (Univ. Iceland / IMO)
Epected area of air pollution from the eruption today (IMO)
At the main vent along the Holuhraun fissure, a violently degassing lava lake has formed, while fountains have decreased or almost disappeared.
Seismic activity remains mostly at the Bardarbunga caldera, which keeps subsiding. 21 earthquakes greater than M3.0 were recorded over the last 48 hours in or around the caldera. The largest ones were M5.2 at 08:43 and 21:23 on Sunday.
Little seismic activity is now detected in the northern part of the dyke and around the eruption site.
GPS measurements show minor movements. No great changes were detected.
Air pollution with SO2 from the eruption remains significant - depending on wind directions mostly to the N and E of the eruption site.
Eruption continues at similar rates
Update Wed 08 Oct 09:49
Total subsidence of the glacier surface above the Bárðarbunga caldera since the equipment was mounted on 12 September (IMO)
IMO wrote: "Seismic activity around Bárðarbunga, and volcanic activity at the eruption site at Holuhraun, has been comparable to recent days.
Seismicity is low in the dyke intrusion; since the last report at 07:00 this morning around 15 earthquakes have been detected in the northern part of the dyke (less than 20 since midnight) and the strongest one was magnitude 1.1.
About 25 earthquakes have been detected around the Bárðarbunga caldera rim during the last 12 hours (40 since midnight), the strongest event there was magnitude 5.5 at 10:22 on the southeastern rim (and since midnight a 5.0 earthquake on the northwestern rim at 03:51 must be included). Additionally, eight more earthquakes exceeded magnitude 3 since 07:00 (11 since midnight).
Scientists in the field confirmed at 18:40 that the eruption is continuing at similar rates as during the last days; there is no visibility of the eruption site on the webcams."
(from: IMO's update page)
no significant changes in ongoing eruption
Update Fri 03 Oct 20:29Eruptive activity at the Holuhraun fissure continues with little changes. Large amounts of lava continue to erupt from the active fissure vents. Lava fountains are now mostly hidden inside the growing cinder cones along the fissure.
SO2 gas output remains very significant - IMO estimates that 35,000 tons per day are being released each day into the atmosphere, producing a gas plume typically drifting eastwards and affecting air quality in eastern Iceland.
The caldera of Bardarbunga central volcano continues to subside at approx. 0.5 m per day, presumably as a result of magma draining from underneath there into the dyke, totaling more than 30 m so far - a process now often called "slow caldera collapse". Earthquake activity overall has decreased, but is still present under the northern extrusive dyke.
No one can predict the future development of this large and unusual eruption: The most likely scenarios are that 1) it might go on for a while to come, gradually decrease; 2) it could result in catastrophic collapse of the caldera with a resulting potentially large explosive eruption there; 3) it could open new eruptive fissures above the intrusion, possibly under the ice and cause large floods and ash emissions.
It could as well do something completely different. The next weeks to months will probably tell!
Update Wed 01 Oct 15:54No significant changes have occurred. The fissure eruption continues at a similar intensity as during the previous days and the caldera of the central volcano continues to subside at approx. 50 cm per day, accompanied by frequent earthquakes in the magnitude 3-5 range.
Eruption continues with little changes
Update Sun 28 Sep 22:47
Subsidence of the Bardarbunga caldera and earthquakes since 12 Sep (IMO)
Earthquakes under the intrusive dyke decrease slowly, but remain frequent and strong under the caldera of the central volcano, which subsides at a more or less constant rate of 50 cm per day.
no significant changes, eruption continues
Update Sat 27 Sep 21:05Visibility has been poor, but everything indicates that the eruption at Holuhraun continues with no major changes.
Earthquakes continue under the caldera and, to a lesser degree, under the intrusive dyke. The largest quakes today were two magnitude 5.2 and 5.1 events both under Bárdarbunga's caldera this morning. Subsidence of the caldera floor at approx. 50 cm per day (as revealed by GPS measurements) continues as well.
Bardarbunga volcano update: Holuhraun eruption and caldera subsidence continue at the same rates
Update Fri 26 Sep 15:42
No big news in today’s official notes from the Scientific Advisory Board for the Bárðarbunga seismic crisis and volcanic activity. The eruption at Holuhraun continues in much the same way as the previous days, erupting large volumes of magma. The new lava field is still growing and has now completely crossed the track (in Flæður) that leads into the Holuhraun area. At Bárðarbunga, both the seismic activity and subsidence of the caldera also continue at similar rates. Five earthquakes bigger than M3,0 were recorded near Bárðarbunga since noon yesterday, the biggest of which was M5,0 at 16:35 GMT. Some smaller earthquakes were detected around the Holuhraun eruption and in the northern part of the dyke.
Lava fountaining from the main vent (Baugur) which feeds a boiling hot river of lava. Photograph taken by Tom Pfeiffer on 13 September 2014.
Gas pollution from the eruption continues to be a hazard. Elevated concentrations of SO2 were yesterday measured around lake and last night in Reydarfjordur. The Environmental Agency of Iceland is waiting for a shipment of SO2 meters that will be put up around Iceland. Instructions for people feeling discomfort due to the presence of sulphuric gasses are to stay indoors, close windows, turn up the heat and turn off air conditioning. The Meteorological Office issues forecasts on its web-page and warnings if conditions change to the worse.
As for the evolution of this volcanic eruption, the following two scenarios are considered to be most likely. Either the eruption on Holuhraun declines gradually and subsidence of the Bardarbunga caldera stops, or large-scale subsidence of the caldera occurs. In the latter case either the eruption at Holuhraun will be strengthened/prolonged, or an eruption occurs at the edge of the caldera. In both cases a new eruptive vent could form underneath the glacier, resulting in a major melt water flood (jokulhlaup) and an ash producing eruption similar to the one at Eyjafjallajökull in 2010.
Eruption continues at record-breaking lava output rate
Update Thu 25 Sep 21:25
Webcam view of the eruption this evening (Mila webcam)
Location of today's earthquakes near Bardarbunga volcano (IMO)
So far, it has erupted approx. 0.5 cubic kilometers of lava, covered 40 square kilometers at an average depth of 12 meters.
During the past 150 years, only the Hekla volcano eruption in 1947 (which however lasted 13 months) has produced more lava. If the current activity goes on for another 2 weeks at the same rate, it will beat this record.
Gas releases are record-breaking figures: approx 10-20,000 tons of gasses (mainly SO2) are released each day.
A road (Gæsavatnaleið) used to access the eruption has been covered by lava flows, making it more difficult to geologist to get to the eruption.
A magnitude 5.2 earthquake occurred this morning under the Bárdarbunga caldera, which keeps sinking at 50 cm per day. Its total subsidence is almost 30 meters now.
Earthquake activity has slowly increased again under the active dyke, which could indicate increasing pressure and involves an increased risk that new fissures open up, possibly under the glacier.
Eruption continues with no changes
Update Wed 24 Sep 22:52No significant changes occurred at the ongoing eruption.
Eruption continues with steady and large lava output rate
Update Tue 23 Sep 08:51The fissure eruption in Holuhraun continues with similar intensity as during the past days and shows no sign of stopping soon. The latest satellite images indicate that the lava now flows into two main branches, one (the older one) to the north and a new one to the east.
Astonishing lava volumes:
The lava flows erupted since the beginning cover around 37 square km and comprise a total volume of 0.4-0.6 cubic kilometers. If compared to an explosive eruption (for which the VEI scale was designed) using the Volcanic Explosivity Index (VEI) scale, the eruption has already reached the category VEI 5. It has so far erupted about the same volume of magma as the 1980 Mt. St. Helens eruption.
The discharge rate was estimated to 250-350 cubic meters per second. For a full day (86400 seconds), this corresponds to a cube measuring approx. 300 m on its sides. It would be enough to fill a soccer field with a pile 2-3 km tall of lava!
The subsidence of the Bardarbunga caldera continues with same rate as before, approx. 50 cm each day. It has now subsided by almost 30 meters in total.
Satellite image from 22 Sep, showing the 2 main lava flows from the Holuhraun eruption (image: Institute of Earth Sciences. Landsat 8, NASA & USGS)
Lava flow map as of 20 Sep (Institute of Earth Sciences)
Update Mon 22 Sep 11:10The volcanic activity at the Holuhraun eruption site appears to be stable, IMO wrote this morning. Seismic activity continues mainly under the caldera, but has been lower than in past days.
Quakes under the intrusion dyke are few and very small (below mag. 2). This is the expected scenario while the eruption is ongoing. It creates an equilibrium between magma input and output and prevents pressure build-up that would cause new intrusions (fractures) with associated larger earthquakes in that area.
Magnitude 5.4 earthquake and sudden 20 cm drop of the caldera
Update Sun 21 Sep 18:09A magnitude 5.4 earthquake under the caldera earlier today was associated with an abrupt drop of 20 cm! The following graph shows the ongoing subsidence during the past 3 days (1.5 m):
Subsidence of the Bárdarbunga caldera during the past days; note the drop associated with the latest M5 quake (IMO)
Eruption and seismic activity continue
Update Sun 21 Sep 11:32The eruption continues with most activity (lava fountains and lava flow emission) now occurring from the central vent on the Holuhraun fissure.
Seismic activity remains elevated, mostly under the northern rim of the caldera of the central Bárdarbunga volcano, but also under Herðubreið and the northern part of the intrusion.
A slight increase in earthquake activity under the caldera can be seen over the past days. The 4 strongest events today so far were between magnitude 3.4 and 4.8, all under the Bárdarbunga caldera, which continues to subside.
This process of slow caldera collapse likely explains most of the earthquakes occurring there. Rapid subsidence by as much as 20 cm has been detected during some of the recent larger (magnitudes around 5) quakes. On the other hand, other quakes have not been associated with a detectable drop of the caldera floor.