“How strangely Fogo burns, amidst an ocean full of flying fishes” & The Friday Night Riddles!

Fogo - aerial shot taken from an Airbus cockpit 2008. Photo by Aldo Bien, Wikipedia.

Fogo – aerial shot taken from an Airbus cockpit 2008. Photo by Aldo Bien, Wikipedia.

We apologize for coming out a bit late with this article on Fogo, but as you all know, Real Life does not care for our hobbies. Yet, it is still in good time as the news from Fogo are not getting less, in the opposite, more and increasingly sad news can be read throughout the internet and local news papers.
December 1, 2014: “Today, Tuesday, is the worst of the 10 days of volcanic eruption on the island of Fogo with Portela village wrapped in flames, ash and the tears of people who once built their lives there…

Lava destroying private property (courtesy of Fogo News)

Lava destroying private property (courtesy of Fogo News)

Some people ventured closer to get a better view of the rare eruption. Photo: BBC

Some people ventured closer to get a better view of the rare eruption. Photo: BBC


Cape Verde, or Cabo Verde, officially the Republic of Cabo Verde, is an island country spanning an archipelago of 15 volcanic islands in the central Atlantic Ocean. Located 570 kilometres (350 miles) off the coast of Western Africa, the islands cover a combined area of slightly over 4,000 square kilometres (1,500 sq mi). It is independent from Portugal since 1975.

Fogo Island. Kartographie: Lucete Fortes/Pitt Reitmaier Design: Pitt Reitmaier

Fogo Island. Kartographie: Lucete Fortes/Pitt Reitmaier Design: Pitt Reitmaier

Fogo (or Ilha do Fogo, Portuguese for “Isle of Fire”) is the most prominent island of the Sotavento group of Cape Verde: it rises to nearly 3,000 m (10,000 ft) above sea level at its summit, Pico do Fogo. Fogo was discovered in 1460 by a Genovese captain António Noli on behalf of Henry the Navigator and the Portuguese Crown, and was first called São Filipe, Saint Philip, in Portuguese. The Portuguese settled the island in 1500. There are now two main cities in the island: São Filipe (the capital) and Mosteiros. Fogo gained its current fiery name before the 1680 eruption, since a madrigal “The Andalusian Merchant” by Thomas Weelkes (?-1623) sings “how strangely Fogo burns, amidst an ocean full of flying fishes”. There are now two cities in the island: São Filipe and Mosteiros.

The island of Fogo has active volcanoes with marked intensity at Chã das Caldeiras, a double depression generated from a caldera collapse and flank sliding event. The eastern half of the caldera is occupied by the main cone – Pico de Fogo. The peak reaches a height of 2.829 meters, crowned by a 500 m wide and 180m deep crater. In Fogo eruptions take place at intervals of 20-30 years on average. The more remarkable eruptions occurred in 1785, with the formation of deltas and coastal lava platforms on the eastern seaboard, 1799, 1847, 1852, 1857, 1991, 1995 – and the current eruption. The eruptions have caused significant damage to the local economy but no casualties, except for the 1847 eruption, which was accompanied by earthquakes, that claimed human lives. Several thousand people live in small villages and towns within the western half of the caldera.

The island of Fogo is an immense volcanic edifice measuring 25 km in diameter and 81 km in perimeter, which rises 7000 m from the bottom of the ocean, in which about 100 minor cones have opened, all located on the radial fractures affecting the island. The whole of the central depression has a perimeter of 9 km and 2 km in width. The caldera rim, called Serra da Bordeira, reaches heights ranging from 400 to 1,000 m at the Mount Liso da Fonte. For some authors there are two calderas separated by a ridge located north of Portela. These two calderas would have lengths of 4.5 km (the Northern one), and 5.5 km (the Southern). Both historical and recent eruptions occurred parallel to the perimeter of the main edifice and very sporadically in the central crater – the last central crater eruption took place in 1799.

Chã das Caldeiras before the latest eruption. Wikimedia Commons

Chã das Caldeiras before the latest eruption. Wikimedia Commons


Image NASA Nov. 25, 2014

Image NASA Nov. 25, 2014

On November 23, 2014, the Fogo volcano in the Cabo Verde (Cape Verde) islands began erupting for the first time in nineteen years. It began with an explosive eruption followed by lava fountaining. Between two vents a new rift ripped open and produced three lava streams down into the caldera. Spewing thick lava and a plume of gases, the volcano has not yet claimed any lives, though it has altered many. According to news and scientific reports, so far the new eruption is the largest since 1951. According to news reports, no deaths have been caused

Nov. 2014 eruption (courtesy of INVOLCAN-OVCV)

Nov. 2014 eruption (courtesy of INVOLCAN-OVCV)

by the eruption because local residents and visitors were timely evacuated. The main road to the villages of Bangaeira and Portela has been overrun by lava, and most of the buildings at the nearby national park have been destroyed. A sizable portion of the land consumed by the eruption was covered with vineyards, so officials are concerned about the loss of a key crop.


Starting today a team of scientists from the C4G Consortium, which integrates 11 Portuguese universities, will proceed into the installation of instruments for volcano monitoring. A total of 10 seismometers and 7 GPS devices will be placed in the caldera and its vicinity to monitor, in real time, the seismic activity and possible ground deformation regarding new magma ascent. Leading the team is Dr. Segundo Rui. Currently are working in the area of Chã das Caldeira scientific teams of the volcanological Observatory of Cape Verde (OVCV), of the Instituto Volcanologic de Canarias (INVOLCAN) and a team of English volcanologists.

Human and technical resources of INVOLCAN (Canary Islands) went to Cape Verde to help to take records on current eruption. The results of their research from material collected of the volcanic plumes (that have reached up to 5,000 meters high) showed Sulphur dioxide (SO2) emissions up to 12,000 tons a day.
The first preliminary results obtained by the use of optical remote sensing type miniDOAS, reflect the rate of emission of sulphur dioxide (SO2) recorded on November 28, 2014, 5 days after the onset of the eruption, was of 8.350 ± 1,344 tons a day, registering an increase of 11.926 ± 3.379 tons per day on November 29, 2014. For the calculation of these emissions, in addition to transects with optimal remote sensors type minDOAS in terrestrial mobile position (vehicles) or mobile position air (helicopters), scientists need to know the speed and direction of the wind between 3,000 and 5,000 meters height provided by the Toulouse VAAC Center. Volcanic gas emissions reflect the amount, depth and content of volatiles in magma inside the volcanic system and is an important monitoring tool to elucidate the changes in volcanic activity. Usually the rate of emission of volcanic gases from an eruption refers mainly to the amount of emitted sulphur dioxide (SO2) – one of the main components of volcanic gases, which is easier to detect by remote sensing than other components in volcanic gases.

Fogo. Lava bubble just before fountaining (courtesy of INVOLCAN-OVCV)

Fogo. Lava bubble just before fountaining (courtesy of INVOLCAN-OVCV)

Fogo Radar observation – Sentinel 1: Deformation on the ground causes changes in radar signals that appear as rainbow-coloured patterns. Scientists can use the deformation patterns to understand the subsurface pathways of molten rock moving towards the surface. In this case, the radar shows that the magma travelled along a crack at least 1 km wide. “By acquiring regular images from Sentinel-1, we will be able to monitor magma movement in the subsurface, even before eruptions take place, and use the data to provide warnings,” said Tim Wright from the University of Leeds and director of the UK Natural Environment Research Council’s Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics. This is particularly valuable in places with few sensors on the ground. (Thanks to reader Virtual for this interesting link!)

Eruption filmed on Fogo island (Cape Verde) in the night of 29-11-2014 by “kapverdischeinseln”


Before.... and after. The newly built visitor center of the National Park has been completely destroyed (courtesy of Fogo News)

Before…. and after. The newly built visitor center of the National Park has been completely destroyed (courtesy of Fogo News)

Nov. 30, 2014 According to Infopress (Fogo News) about 9 o’ clock in the morning the building of the headquarters of the Natural Park of Fogo has been totally consumed by the lava that has increased its speed to 20 m/h. According to the volcanologist Dr. Sonia Silva on Saturday sulphur dioxide emissions emitted by the volcano was estimated to a 8,000 tons, while today this value has increased to up to 12,000 tons. For the scientist, this increase implies a deterioration of the eruption conditions. In the last hours, according to INVOLCAN members, the eruptive dynamics has changed from strombolian to vulcanian, with the onset of powerful explosions.

Nov. 30, 2014 (INVOLCAN) Report of a rapid change in the behavior of the volcano, experiencing a brusc variation between eruptive styles. The presence of lava fountains and strombolian phase has begun to alternate with vulcanian phases dominated by violent explosions. The lava flows have resumed their advance and is proceeding with the evacuation of people who remain in Cha das Caldeiras.

Dec. 2, 2014 (OceanPress) Despite the instability of the volcano and the damage caused by the same, the mayor of São Filipe, Luís Pires appears to be optimistic about the future of agriculture in Chã das Caldeiras, the main source of wealth on Fogo Island. “The few lands that remained will be suficient, so we are thinking about new technologies of agricultural production will be activated in this locality wih good climate”, he grants in an interview with Radio Renascença. “I understand that everything is not lost. Chã das Caldeiras, as agri-industrial and turistic potential, will be reborn greatly after this eruption”, completes the mayor of the city of duplexes.

Dec. 3, 2014 (Fogo News) This Friday 4th a ship of the Portuguese Navy, “Alvares Cabral”, arrives to the city port, with a helicopter, which is providing humanitarian support to those affected by the volcanic eruption in Fogo. Concerned about the [Wine]Cellar and the road, the President of Civil Protection on Fogo Island says the device will facilitate the circulation and the supply of staff who will be in Cha das Caldeiras. According to Luis Pires, will be also the coming of important telecommunications equipment and even aid goods such as beds, blankets and masks.

Dec. 3, 2014 (Fogo News) Cape Verde had sufficient data to predict eruption in Fogo – Available data from the Technological Institute of Renewable Energy of the Canary Islands (ITER) indicated a strong possibility of a volcanic eruption on the island of Fogo – Was it heeded by the authorities?

Lava destroyed school, Hotel Pedra Brabo and several houses of Portela, 02-12-2014

Lava destroyed school, Hotel Pedra Brabo and several houses of Portela, 02-12-2014 (Courtesy of “Capverde.com”)

Residents from the villages down in the caldera carry their important belongings uphill to save them from being burnt by the fast advancing lava. Photo: BBC

Residents from the villages down in the caldera carry their important belongings uphill to save them from being burnt by the fast advancing lava. Photo: BBC

Renato Rio started this post on Fogo but could not finish it because of rl obligations.
Also thanks to our readers for links and info!


Dec. 3, 2014 (rtc TV): 70% of the village Portela have now been destroyed… see latest Video (thanks Renato!)

Dec. 5, 2014 (GEOVOL): Activity at Fogo increased in the last hours. A very fluid lava has been emitted since yesterday from the vent at the bottom of the eruptive fissure at a speed of 3m/min. It follows a path parallel to the previous one to Portela village. In the video courtesy of Fogo News
http://videos.sapo.pt/JNHOwDA6NEf4bSPr7a99 its fluidity can be seen. Also the reporter speaks of water tanks being contaminatedand which supply Tinteiras population, following the fall of volcanic ash. – Another issue at hand is the discussion on neglected responsibilities. INVOLCAN, monitoring and assessing the processes in Fogo, had sent an early warning to Cabo Verde in last March, stating that the volcano showed clear signs of serious unrest with the possibility of an eruption. That letter had not been answered, and obviously people were not sufficiently prepared when the eruption started
Dec. 5, 2014 (OceanPress):

Lavastream– Fogo Eruption opens new front of lava: The situation may become worse with a possible volume of lava that may leave the city of Portela completely buried and may reach Bangaeira and in a worst scenario, the city of the Mosteiros… – The municipality of Santa Catarina, on Fogo Island, plans to build a new village for the displaced from Chã das Caldeiras in “Somada”, a town between Achada Furna and Monte Largo … However, the inhabitants of the town of Chã das Caldeiras are not enthusiastic about this project, as they prefer the new village to be built in the region of Monte Velho…
– Professionals working in the caldera suffer health problems from toxic volcanic gases…

NEWS and VIDEOS (fb=facebook)
Observatório Vulcanológico de Cabo Verde (OVCV) (fb)
Grupo de Investigación GEOVOL (fb)
Ocean Press
Capeverde (fb)
Fogo News
Mark Szeglat’s Volcano Blog (in German)
– kapverdischeinseln

Wikipedia, Fogo
Gonçalves: Vulcanologia e seus Impactos no Concelho de Santa Catarina–ilha do Fogo
Correia/Costa: (Concise description of the Fogo eruption 1995 and its consequences, in Portugese)
Ocean Press article Dec. 2, 2014
Many Infos and images were used from the above mentioned fb accounts.

238 thoughts on ““How strangely Fogo burns, amidst an ocean full of flying fishes” & The Friday Night Riddles!

    • And thanks to our ad-hoc Portuguese linguist Renato Rio who helped noodle out information!

      Note to all: Many times our posts are actually the work of a few people collaborating on the topic, gathering material. It’s a bit chaotic at times, but it works and allows us to mitigate the callings of real world tasking when trying to find time to research the article.

    • Thumbs up Granyia and Renato for your timely article
      Fogo Radar observation – Sentinel 1 The radar shows that the magma travelled along a crack at least 1 km wide. Scientists can use the deformation patterns to understand the subsurface pathways of molten rock moving towards the surface

      • DT – do you have a cite for the photo? I’ve seen similar products produced for a few places in the western US that are supposed to show slow movements / stress buildups / deformation along fault lines. As usual, can’t find link for comparative purposes. Cheers –

          • DT – many thanks. It verifies what I thought about the process of creating the interferometry patterns – overlaying datasets taken on different days and assigning colors to differences.

            Are you referring to the linear feature to the east of the crater as the crack?

            Almost looks like there are two areas of uplift – the North of the crater (assuming North is up) and to the east of the crater, which would make what looks like a crack to be a fairly steeply inflated part of the island (and candidate for a weak spot in the cone). Interesting stuff. What do you think? Cheers –

            • looks like the confirmed large dyke/crack to the E & inflation under the crator and a candidate for a dyke/crack weak spot in the cone to the NW In this case, the radar shows that the magma travelled along a crack at least 1 km wide. “By acquiring regular images from Sentinel-1, we will be able to monitor magma movement in the subsurface, even before eruptions take place, and use the data to provide warnings,” said Tim Wright from the University of Leeds

  1. Before I started learning about volcanoes, I thought of lava as a hot liquid that ran like a river, not the goopy mush with the consistency of bread dough several meters thick that crackles and sings as it devours forests and buildings. My heart goes out to these people who can only watch as the lava takes their homes and livelihoods. So very sad..

    • I’m not sure who did most of the grunt work on that article, other than knowing it wasn’t me. All I did was toss in an observation that the SO2 is probably not going to have a long term climatic effect, but the azaleas are going to love it. 🙂

  2. Thanks for the post Granyia & to Renato for the help with it. I’ve enjoyed reading and learning many things here on VC. I’m always so busy but still find time to come here. When I get on here, I feel like I spend most my time catching up in case I may miss something. 🙂

  3. Unfortunately, most people do not have a choice about living near a live volcano.

    Today, I was taking a class looking at living with volcanoes; how the benefits that volcanoes bring tempt people to be in proximity to volcanic fields, despite the risks involved; and how poverty makes the choice to live elsewhere meaningless.
    I used Fogo as a real-life, happening now case study, using links provided from this site; you have brought them all together in one very good article. Thank you.

  4. It takes time to be a fully grown dragon – both immediate and mediate(d) time. I helped in some of the Portuguese translations and couldn’t finish before news were no longer news – Granyia was my mentor dragoness, to whom I’m most thankful. :)))
    Hope the volcano crisis will wane and people can recover from the blow!

  5. Hope Rio isn’t too busy to come back later. Sad for the people there. Was told by davidcalvo that they had 16 hours notice to leave. Very sad.

  6. My thanks to granyia and Renato. It is always sad to watch personal tragedies unfold as lava. ash, gasses or lahars create havoc. At least these people had a little time to collect belongings., but where to go on a small volcanic island?
    This reminds me of Tristan da Cunha.

    • Yes, it does. Can never forget the poor people fleeing the Island. Saw it on TV back then and can never forget when my father said it was in a straight line from our coasts…

  7. Notes from the meeting of the Scientific Advisory Board (pdf 0.4 Mb)

    The latest update is a long one. It has some interesting info as well (i think.) . 🙂

  8. “What is to happen under Bárðarbungu”.with earth scientist,Ari Trausti Guðmundsson Link to radio interview in Icelandic http://www.ruv.is/mannlif/hvad-er-ad-gerast-undir-bardarbungu

    Kolla says: http://www.jonfr.com/ A very rough translation of the highlights of this interview with Ari Trausti Guðmundsson.

    We have seen key eruptions, like Surtsey and Krafla and now this eruption in Holuhraun, they all add to and change our ideas about what´s going on underground, as it´s difficult to see. Measurements and simulations give us understanding about the hot spot and the tectonic rift and the 30 (local) volcanic systems, how they work. (then he explains some of the tech)

    Theories, based on earlier eruptions tell us that under the (Icelandic) volcanic systems, which are oblong in shape, there are oblong magma reservoirs at the depth of 15-20 km. They collect magma which comes from melting of the mantle. This magma reaches the surface, either directly and forms those shield eruptions we know well, where we are getting 1-3 Km3 of magma, or the magma comes up under a main volcano and stays in the more shallow magma chambers belonging to the volcano in question.

    These theories have been around for some time and I feel they fit this situation well, also Skaftáreldar, Veiðivötn around year 1500, where traditional magma chambers are not necessarily a part of the picture, but rather magma coming directly from a deep magma reservoir.

    Some of the data supports the theory that this Holuhraun eruption is coming from a magma chamber under Bárðarbunga. Other data sets indicate that there is no real magma chamber under Bárðarbunga and the magma is coming directly from deep down. We mustn´t forget that this large dike is flanking Bárðarbunga, so you would need some kind of connection, we would have to let the magma turn around a corner, to get it from a shallow magma chamber and into this dyke.

    I´m not the only one, there are much more prominent scientists than me, like Ágúst Guðmundson in London and Professor Þorvaldur Þórðarson, who agree with me on this. This theory is still a work in progress, we may be partly wrong, partly right. Maybe this is even more complex than we think.

    Bárðarbunga is a unique volcano, it´s not really a cone, it´s more like a huge shield volcano, containing a large caldera. It resembles more the large volcanoes on Hawaii, rather than the caldera of Dyngjufjöll, or Hekla or Öræfajökull. And the system of magma veins (underneath BB) is very unusual and we are first properly learning about this now.

    I can point out, the large eruptions of Bárðarbunga (in the past), they must have come from somewhere else, not just from under the caldera. The volume of the caldera doesn´t match the amount of magma that has come to the surface in this large volcano system. This is very complex and therefore is this eruption so exiting.

    About the subsidence of the caldera, it could tell us that there is magma coming to the surface. In a way these two (BB and Holuhraun) are connected. This all starts with tectonic rifting, magma comes up under Bárðarbunga, there was a dyke shooting out towards Kistufell in the beginning. Then this parallel dyke is formed as well. Most probably there is magma streaming upwards in two places, into the Holuhraun dyke and also into Bárðarbunga, maybe a bit slower.

    This means there are ring faults and cone channels (?) forming, the volcano is heating up, also geothermal activity on the surface. The subsidence is caused by slight rifting, along with the land rising. You can see it on the GPS data, the subsidence isn´t constant. Although the measurements on the top of the ice show subsidence, you can´t project them completely onto what´s happening underneath. There are 800 meters of plastic material (ice) in between.

    This could mean that magma is ascending into Bárðarbunga, which can increase the likelihood of an eruption in the main volcano, and this could also mean that the Holuhraun eruption would go on unaffected at the same time.

    Most of the earthquake activity is on the north side of the caldera, and on the outside of the caldera bowl. And it´s difficult to interpret that otherwise than incoming magma. The subsidence is most definitely 10, 20, 30 even 40 meters, it´s difficult to tell. But there also seems to be earthquakes there that show breakings (?) which point to a rise, it´s like the volcano is going up and down in waves, not just subsiding. This is an idea only a few of the local scientist would currently accept. These theories are evolving as people discuss and collect data and finally the picture will be clear. We must wait and watch a few months, let´s say until the end of next year, then these things should be clearer.

    The latest petrology data shows that this is much more complicated than we thought. Also they have placed an accelerometer on top of Bárðarbunga, which makes it possible for scientists to see the difference in the time of arrival of the earthquake waves, which again helps us to see where the magma is located. It seems that magma is much closer to the surface at the bottom of the caldera than was possible to see with previous measurements. This is filling in the gaps of our knowledge.

    The (Holuhraun) eruption could go on for years. Let´s not forget, the Surtsey eruption lasted four years. And this is a similar thin flowing primitive magma. Let´s say, if this goes on for three or four years, then we´ll have a beautiful shield there (in Holuhraun). What is interesting about this magma, it´s very homogenous, and previous magma coming from the Bárðarbunga system is amazingly homogenous, although you have two types, one in the south part, one in the north part…

    well well well……

    • Very interesting interview! And it seems to fully support your theory DT!
      Some very interesting time lie behind us, but some even more interesting moments are yet to come for sure!

    • Hm. No shallow magma chambers but rising magma (which would form magma chambers)? I’ll take with some scepticism. The existence of a caldera implies an emptying magma reservoir and not at 15-20km depth. There is good agreement between the volume leaving Bardarbunga and the volume leaving Holuhraun and there is certainly some link. None of the available data shows any sign of inflation in the area of the earthquakes. Finally, a good agreement between subsidence rate and earthquake energy rate which was recently confirmed. Science works by model – prediction – test. I’d like to see this make a testable prediction. If it predicts, for instance, localized inflation in certain areas around the rim, that can be tested. The argument here is that the subsidence is in the ice, not the rock. That means something is going somewhere. Have they looked for the missing balance?

      Clearly a volcano on the MAR will behave differently and will be complex. But this view, with the current data, seems far from convincing.

      • The volcanic eruption in Holuhraun: The volcanic eruption that began on Holuhraun on 31 of August is characterised by a large and unusually steady flow of lava. The magma that comes up is a rather primitive basalt, with a chemical composition typical of the Bardarbunga volcanic system. The petrology analysis of the magma suggests that it stabilised at 9-20 km depth, meaning that it could not have resided at a shallower depth in the crust.

        Source: IMO

        What’s your opinion on this statement, Albert?

        • This may well be the depth of the ‘leak’ which is/was draining magma from underneath Bardarbunga. If you hole a bucket, the water that comes out is mainly from the level of the leak. The total amount of subsidence has been about 50 meters. This equals the height of the column of drained magma (times a ‘filling factor’ of the magma chamber). This is small enough that the magma flowing into the dyke comes mainly from a single depth. (It gets more complex if the leak is a tear rather than a hole but the principle is the same). The magma in the shallower chamber percolates down to replace the drained stuff. This percolation takes time, and is why the surface responds a bit slow to the draining (the cause of the exponential decay). It all seems to fit. For me, the fact that the earthquake energy is decaying exponentially at the same rate as the subsidence was the big point in favour of this model. I had been looking for this signature and I feel it counts as a prediction! The model above does not predict such a relation.

          Note that I am not against magma being present close to the surface of Bardarbunga. decreasing pressure can also cause more melt adding to the magma, But that is not the dominant process. The big event has been the removal of magma from underneath Bardarbunga into the dyke system. I think I wrote that in last week’s post as well – although I also noted that nature does not pay attention to my opinions…

      • I think the key phrase in this interview is “This theory is still a work in progress, we may be partly wrong, partly right. Maybe this is even more complex than we think.”

        I do not feel that it is “difficult to interpret” the activity in the north being related to the sink and reduction in pressure inside the core, in fact the evidence suggests the reduction in total quake energy is following the same pattern of decay as the subsidence

        There is still room to argue for many different scenarios

        Regarding the hydrothermal activity increase

        While looking back at past earthquake history around BB I found this interesting fact I thought I would share. It seems that quakes can trigger hydrothermal activity for quite some distance. This was regarding two large M6.4 quakes in 2000


        “The earthquakes were felt in Iceland within 200 km distance from the epicenter. They caused no serious injuries for people. The highest measured maximum acceleration was 84% of g in the June 21 earthquake according to the Earthquake Engineering Research Centre, University of Iceland [3]. Maximum acceleration in the June 17 earthquake at the village Hella was 47% of g [3]. No houses were collapsed but several houses are, however, so badly cracked that they have to be abandoned. Several incidents were reported of broken pipelines. Open surface fissures were observed with an opening of around a meter at various places along the faults.

        Hydrothermal activity increased substantially in a large area around the two faults. It has been estimated that the thermal power equivalent of the increased flow of hot water to the surface is around 100 MW. The great geyser, Geysir, that gives its name to all the geysers in the world, 30 km to the north of the faults, erupted again, after being more or less dormant for more than half a century. Water level changes in boreholes, observed immediately after the earthquakes, agree very well with the observed mechanisms of the earthquakes, i.e. raising water level in the areas of compression and lowering it in the dilatant areas. The hydraulic pressure change was in the order of 2-13 bars in wells sited only few hundred meters from the fault lines, in the range 0.5 to 2 bars in the next 1-2 km radially out and 0.1 to 0.5 bars as far as 100 km from the seismic faults”

      • “”Finally, a good agreement between subsidence rate and earthquake energy rate which was recently confirmed.”” There is no such thing as right rate of subsidence to quake energy. I think what you quote is that it is possible to explain the energy released in quakes by the subsidence. It would mean that the SIL stations measure all this energy, which is perhaps not likely.

      • Albert, for curiousity, how would you make a testable prediction of this volcanic system? I am conjuring up all kinds of images…. but never mind for now.
        In geology your model-prediction-test is a tad harder to arrange. For one, geology attempts to describe events that are way beyond our time scale. Perhaps, most of the time.

        • I think that is the unique aspect of this eruption. The long lasting eruption, the clear process of dyke progression, the regular subsidence, and the very long sequence of earthquakes provide enough time to make and test predictions (such as, evolution of earthquake energy, balance of magma flows, local inflation versus deflation, ..). That is not often the case. Normally eruptions (or earthquakes) are sudden and short.

    • Me and Ari seems to be relatively on the same page by now. I made an English overview of my blog from the beginning of the Bárðarbunga event, it might clear some things in the diagram I posted earlier.

      • Hi Gudmundur

        The one area I cannot wrap my mind around is how there is magma leaving and magma rising in the core at the same time?

        How is this flow happening in your diagram, are there areas of up flow and areas of down flow that are not connected?

          • I do not see it in the diagram but in the write up. If there is rising magma up to the top how is it going back down and out to HH?

            I cannot see how this works, rising magma to the top yet sinking in the core and now around the rim.

            ” If this is the situation, BB top magma chambers are getting fresh hot magma which is, and will be eruptible in future.”

            “Today we can look at the situation as being “stable”, where magma flows from common source up to the top magma chambers of BB and out to HH.”

            • Ian F. “”If there is rising magma up to the top how is it going back down and out to HH?””
              It does not. Magma flows from the common magma chamber under the entire system. Simultaneously, the lower part of the plug is falling faster than the upper part.

            • The latter one could read also “…1. from common source up to the top magma chambers and 2. from common source out to HH.” Of course I did not write it.
              But, for an argument, the rifting is mangling the BB. At the same time, hot spot is acting up and “pushing” fresh magma into the whole system. Actually, I do not remember seeing inflation/deflation data for more than one point on BB? Have you? Please inlighten. It is still possible to have movement there without we having seen it. That magma is rising up, seems to be so, and then it would fill cracks etc in the country rock. If indeed there is molten magma below the plug, would seem logical that the magma is not that steady a foothold for the plug. In fact, the magma might want to escape, because it is lighter, and that means where the energies would seem the easiest. All the earthquakes there… an opportune time for some magma or its fumes to fill into.
              Though personally I am not so convinced about the plug, but for now it may seem to fit the model.

            • Yes, the pattern of quakes point to this is a way. There is a rise and fall to the depth of the quakes, but I could reason that the chamber below 10km is seeing a reduction in pressure and the bottom collapses first and the top follows later due a slow structural collapse over the northern area.

              I do not see any rising pattern to the quakes

              Are you are suggesting is the whole area around BB is sinking lets say 1m per week, and the magma is creating a rise of .5m per week so we see a sink rate at BB of .5m per week? Just using random numbers here.

              If this were the case the there should be a significant difference in the amount of sink compared to what is expelled at HH. Todays IMO statement says 1.0km^3 at HH, .5 km^3 in the dike and two days ago 1.4^3 of sink. These match up pretty close and I would suggest that there was a volume of eruptable material already in the dike so if there is more at HH this could account for it along with decompression melt.

              I see no rising GPS anywhere, just sink? (other than Kverkfjoll which continues to rise)

              I see no unaccounted for volume at the surface more than the sink?

              So I cannot see any new injection of magma anywhere or any evidence of rising magma.

            • Ian F. This is all information that I think fit well with the diagram. For example, the caldera rim started to fall after September 13.

              If we would put plug in HH now, would then BB rise or fall or just stop. ?

            • Gudmunder

              I think your diagram is an accurate model of below BB, I just do not see any input of magma into the system. I think that rifting caused stress around BB and the “squeeze” caused it to push magma from the chamber 11-15 km down and out into the existing dike. This was the easiest path to release the pressure, it happened before.

              So to answer, if this is correct then BB would stop sinking. If this happens and BB rises right away then the theory of a new injection would hold more merit in my mind. I guess we will have to wait a see 🙂

              This is not to say that due to all of this activity a path up to the surface may open up, I just do not see the evidence yet, but not being an expert I may be blind to any signs of this happening.

            • @ Ian F 14.34

              One thing about your view that puzzles me – ignoramus that I am – is what is causing all the signs of dyke and cone sheet formation on the NE side of Bardarbunga? Magma injection seems a good account, and is presumably supported by drumplot data. Is your view that it’s down to the rifting?

            • @am57

              Here is my theory 🙂

              The quake patterns suggest there is a “chamber” or large pool of very hot material that extends under the rim on the NE side at a depth about 11km+. This means the pressure in the chamber supports the roof.

              As soon as the leak starts the reduced pressure in the chamber results in two things. First, the core under the caldera losses pressure and volume as the magma moves downwards to fill the void in the chamber below. Second, the “roof” of the chamber no longer supports the NE rim area it is undercutting.

              So what we see are quakes in the “hard rock” as the pressure reduces support, adding to the tectonic stress already there that created the leak in the first place.

              If you look at the graph of depth over time above the quakes run deep for a period of time and then both shallow and deep, this pattern has cycled about 5 times in total since September. Cause: If the roof of the chamber looses integrity it would fracture and then this would slowly transfer up the structure all the way to the surface. Of course the deep structure would have the most pressure so it fractures for a time and then the shallow area follows in spurts.

              The pattern of quakes suggests the south side does not have anything undercutting it and the “wall” of the core on the south goes down to 12-13km is sloped inwards to the center. The north side quake pattern suggests an outward slope. This would mean as the core sinks the support under the entire north side is reduced but this is not the case on the south side.

              Is there magma going into these cracks and openings? Most likely but right now I have not seen any sustained tremor in the drum plots that would suggest this is happening to a great degree. Also, some of what looks like magmatic quakes on the drums I believe is due to the waves travelling through the core of BB.

              Could all this change? yep, at any moment

              Could I be wrong in my thinking, chances range from good to very good 🙂

            • Well, that makes a good deal of sense to me, not least because as you went on you addressed the objections that were forming themselves in my head. One item of my (tiny) knowledge that doesn’t seem to fit is that the caldera rim shows signs of rising, though more in the S than the N.

              Perhaps this could be accounted for by the effects of rifting. But perhaps it could also be accounted for by differences between the cycles of subsidence of the plug and of injection of magma from the mantle, which then forces its way up weaknesses (which are mistakenly inferred to be “dykes” and “cone sheets”) and causes the small amounts of inflation and some of the earthquakes. Objection: your reading of the drumplots and the tremor gauges…

            • The first overflight which found the subsidence indicated rising around the edge. This was not confirmed later. It may have been a calibration error. I like your model and expanation, Ian.

            • It’s shown – only a few metres, mind – on the IMO diagram you posted at lunchtime today! And I think it has been mentioned in one of the IMO public documents – though I must say, they are so good in circulating material that I am not absolutely sure whether it was one of theirs or an Icelandic newspaper report.

      • Gudmundur, more or less I think along your and Ari’s lines.
        I have been wondering about the hot spot, which is probably quite a large or perhaps wide system.

  9. I have added a section for Updates on Fogo below the Post, for new reports, videos, developments etc. So, whenever you stumble on something that should be noted there, please let us know. Thanks!

  10. Because there have been so few daily quakes over M3 lately, I haven’t bothered producing summaries for them. However, it occurred to me today that summarizing two days’ worth might be a reasonable interim measure. So here is the summary for the 1st and 2nd of December:

  11. Nice to have read Ari Trausti Guðmundsson.
    He seems to support my theory of a shield volcano building up at Holuhraun 🙂

    But interestingly he adds the twist that some of guys have added and should have merit, that M5 earthquakes can be caused also by rising magma. It seems I was not seeing the big picture on that one!

    • Also the claim that BB caldera is rather more of a shield volcano supports what Carl has suggested once, and it makes all the sense. It’s a large source of incoming magma from the plume, but it also rifts and sinks at same time.

  12. Woke up to plenty of snow. A beautiful winter day in Iceland. Calm winds, hard frost, and a thick white blanket. There seems to be just a few quakes on Iceland today, besides the usual M4s.

    Also a slight increase of quake activity in Tjornes. Maybe a swarm will start in there…

  13. Very nice work! And interesting volcano. Aren´t they all!
    About living in dangerous places, in the times of quiet they do not seem so… In the same vein, there are whole cities built on barrier islands in the eastern US. And guess what? These islands, by their very nature, migrate northward. This means the sand grains are brought by waves from the southern tip over to the northern tip, and eventually, the whole system moves… though slowly. Truly, grain by grain.
    Do people worry? Probably do not have the understanding…

  14. I was planning on writing a contribution to the Friday post last week, but there simply wasn’t any time for it, but let’s have a go at it now instead.

    Somewhere in the beginning of the eruption, it looked like the estimates of the lava flow at Holuhraun did not match up with the volume of the caldera subsidence. This observation, together with indications that magma had a deep origin, let me to beleive that the eruption was fed by equally large flows from the subsiding caldera and from a deeper source connected to the mantle. In that scenario, it would be possible for the subsidence to reach an equilibrium and stop, while the eruption could still continue, fed only by the deeper source. With the same assumptions it would also mean that if the eruption were to stop, the pressure reduction causing the subsidence would disappear and the subsidence process would reverse, possibly triggering an eruption at the caldera rim.

    Now, looking at the latest figures of estimated volumes, things look a bit different. It is now estimated, from GPS data and satellite interferograms, that the volume of the dyke intrusion is about 0.5 cubic kilometers. Air measurements give an estimate of 1 cubic kilometer of erupted lava (0.3km3 uncertainty), and the volume of the depression bowl from the subsidence is estimated to about 1.5 cubic kilometes. To me, this looks very much like 1.5km3 of magma has left the deep magma chamber under Bardarbunga, causing everything above it to move down, shaking the ground along the way. Two thirds of the magma has erupted at Holuhraun and one third is left in the dyke.

    In case no further rifting occurs, the simple (and boring) conclusion is that the first scenario is probably the most likely to happen, i.e. the eruption will slowly come to an end and the subsidence will stop.

    • Yes, this is now clearly stated along with no ice melting causing the sink

      “Subsidence of the Bardarbunga caldera: In the days following the onset of the seismic unrest, the ice covered base of the caldera began to subsidence up-to 80 cm a day, but the subsidence has since
      slowed and it is now around 25 cm per day. The subsidence is in the shape of a bowl and it is greatest
      in the centre of the caldera, about 50 m, but smaller to the edges.”

    • Regarding the size of HH the evaluation reported yesterday. Just over a month ago, it was more than 1km ^ 3 according to IMO. according to yesterday’s opinion flætið to HH 100 m ^ 3 / s in November. it would then be about 1.3 km ^ 3 now ??

      • It looks like all the numbers have been adjusted down compared to initial estimates. Previously, flow rates of 300-350m^3/s were reported, but yesterday’s report says that flow rates in September were “only” 200m^3/s. This suggests that the 1km^3 reported by IMO one month ago could also have been overestimated.

        • Or maybe these information from IMO is not as dependable as might be expected. It’s easiest to evaluate flow and volume in the beginning. Now magma is thickening the lava field, even where we see no flow. The area increase has ceased to be a significant reference and its getting harder to estimate the volume ?

  15. They are going to try to put a relay up for the BB GPS on Friday (5th Dec), weather permitting:

  16. Ian F, in the previous page you made a comment about magnetism. It seems that the first map you posted is residual magnetism, and the other is total magnetism. Residual takes into account the magnetic declination, the total does not. Sometimes comparing several different magnetic maps one can draw conclusions. Also, comparing to geologic map, or known geology and unknown. Then, taken into account that these maps are on the scale of the whole of Iceland, not too much could be inferred for the exact location of BB.
    Magnetic maps are a great tool, but depends what you want to do with them. For example, take a note that the MAR is quite nice outside Iceland, but becomes quite unclear within the island… And if I am talking nonsense then please somebody correct me…

    • Thanks for the info 🙂

      Would have been very interesting if you could put something definitive to the maps, especially the large blue areas between BB and Kverkfjoll. Also the red spot that seems to have put a stop to HH fissure and the apparent opening to the Askja caldera from the south.

      I wonder with all of the seismic data they have collected since this thing started if they can use that to do some sort of mapping of the mantle under BB

  17. The surface expression of subsidence in the BB caldera looks very similar to the surface expression over of a block cave mining operation but keep in mind block cave planning is hideously tricky. The interplay of existing faults and cave advance leads to some unexpected results.

    Suggest you look at the link below. There are some excellent animations of block cave collapse and propagation. The collapsing blocks of the plug could be causing the not so primitive magma composition at HH through partial melting of the in falling material into the magma chamber and assimilation of said material. Then look at the surface expression of active block cave operations.

    The preponderance of faulting on the north side of BB may have something to do with pre-existing weaknesses and at higher levels the lack of confining pressure due to proximity to the edge of the volcanic edifice.

    The onset of rifting provided a path of lesser resistance for the magma in the chamber under BB. The release of pressure allowed the base of the plug to commence caving into magma pool. Of course I could be totally wrong….

    If the link does not work just search for “block caving”

      • I have been chasing a childhood memory since this started, with the caldera sinking – and now here it is, illustrated – shovelling coke out of a coal bunker – one of these:

        🙂 🙂 🙂

        • Oh yes! It is like shovelling coal out of a coal bunker – only it’s magma leaving the system that is causing the collapse. Great analogy, Jane!

          • Yes – and there must be different sizes of rock – I wonder if they are sorting themselves and packing themselves tighter as they drop and get jiggled by all the earthquakes. The animation actually shows pieces of rock rotating as they fall.

          • Thanks for the link – very interesting!

            Oh yes – the grain idea fits too – I’ve seen that in operation having lived in wheat country for a couple of years. 🙂

      • Fascinating. Now I’m trying to imagine the effect of some existing ring faults and magma and gases and water and temperature and pressure and rifting and the hot spot. It’s all so clear now. 🙂

      • Cool video.
        If there were liquid mixed in this with a lower density than the rock grains, wouldn’t it move up in relation to the grains.? In our case there is magma with lower density in the equation ?

        • I could see that but how much upward force would buoyancy alone create? Enough to run it up to the surface?

          I am not discounting magma coming up to the surface at all, lets say with all of this cracking and pushing it is much more likely than before August and as a non-expert I think I can say this and not be wrong 🙂

        • I think an important mechanism at work here is the introduction of primitive and really hot magma from lower chambers and possibly directly sourced from the mantle. If the chamber is closed – no new magma re-charge then given the (albeit high) thermal gradient in Iceland, the upper chamber would be slowly cooling, forming a carapace of solidified magma on top of the chamber/bottom on the plug. Once new and hotter magma is introduced, initiated by the rifting event the hotter magma can physically melt the older carapace and country rocks. I have seen this in many places. Incipient melting of the wall rocks around a conduit takes the forms of granophryic melts exploiting both compositional differences and precursor structural weaknesses in the wall rock. Blocks of the wall rock can physically fall into the mafic melt forming xenoliths of any size – up to and including km sized floaters if the chamber is big enough. The issue then become – is the volume and velocity of the new magma entering the chamber is sufficient to maintain those xenoliths as “floaters” entrained in the magma or do they start to sink and start clogging up the conduit below. In any case – exfoliation of wall rocks and the BB plug due to high temp melting or extreme thermal gradients caused by new magma is probably happening. Pretty much like the block cave animation above.

          Letting my imagination roam perhaps a little too far, I could envisage xenolithic debris from chamber wall rocks and from the plug itself falling into conduit feeder at the base of the upper chamber and perhaps initiating a slow down of newly available magma. Perhaps the pulsing we have witnessed is due to large blocks falling onto and then being pushed aside by the over pressured new magma from below. Trying to put a cork back into a foaming champagne bottle so to speak.

          Fun to speculate…..

          • It is fun to speculate – and even more fun to read when you agree with it. 🙂 This is also what I think has been happening and that there is new magma directly sourced from the mantle coming into the system. The reason we’re not seeing it as inflation is because either the new magma is only reaching as far as the the lower reservoir which is feeding the dyke while upper reservoirs are also flowing down, or because there is just more magma leaving than incoming. I think what started this period of unrest on August 16 was a massive injection of magma into Bardy’s system from the mantle and that this new magma exploited dykes, initially in two directions, before focusing on the one going to Holuhraun, which acted as overflow pipes allowing evacuation of magma from upper chambers and the subsidence of the plug.

      • I’m fascinated to see how, after the initial diagonal fault, the shattering planes seem to curve from the top, forming arcs towards the fault to the left. Could this somehow explain the undercut to the northern rim, where many of the earthquakes are ‘outside’ the caldera rim?

      • Great video. I take your point Ian, it’s just that I’m not sure your theory can account for all that has been observed at the caldera – see my replies to our earlier discussion.

  18. Drop in the strain meter at STO. No idea what that’s about – they only just got it back on line and it’s been jumping about all over the place – so it might be a ‘valve open’ drop while IMO re-set it. We’ll just have to watch and see.

    • I’ve noticed that too and also adopted a wait-and-see position. The STO strain meter reminds me of that elephant of GL’s on the trampoline. 🙂

  19. Good to see my original post stimulated everyone’s grey matter……..
    The Alex Vyazmensky collapse gif above is informative, however……..
    at BB there are NO quakes in the centre of the caldera ……so that type collapse/subsidence is ruled out

    What we have is 2 types of quakes for different process;
    1) MAR related tectonic & Graben/Rift subsidence & tension & compression relief
    these are the initial larger quakes followed by reducing after shocks…… followed by more larger quakes followed by reducing after shocks

    2)Volcanic liquid – gas – magmatic – quakes which are the smaller ones mixed in ….but identifiable

    BB is not like a ordinary volcano…… there is no small vent rising from a 5-10km3 chamber to the volcanos peak which would show an abundance of harmonic tremors…….. the BB “magma chamber”…… is the quake void area 8kmx8kmx8km+ deep & open at depth…..it consists of 770c+ crystallised mush & magna …hotter at depth

    3) We have seen harmonic tremors & quakes as liquid – gas – magma has moved into the weakened walls of the the BB “magma chamber” …….caused by the MAR related tectonic & Graben/Rift subsidence & tension & compression relief quakes

    these have produced radial dykes and fractures between the larger quakes faults……

    there is an upward progression of quakes in waves……it just depends on how you call the data & what parameters you use……everything is mixed up so just looking at / plotting the big picture masks the detail
    & introduces bias

    4) The subsidence of the ice cap & volumes is deceptive …it was & still is under tremendous compression…originally it may have been forced upwards in a bow ~20m+ …MAR compression is released in part via expansion i.e. Rift…… & it slowly subsides exponentially …….until it assumes a downwards bow ~20m- at the deepest point

    during this time it showed exponential decay as it rose & fell depending on the pressure within the BB “magma chamber” ……as liquid – gas – magma was forced/ moved into the weakened walls…

    ….. causing the harmonic tremors & smaller quakes in the walls of the BB “magma chamber”….. the easiest path ……..because the caldera floor is under tremendous compression……
    there is no connection magna flow between BB “magma chamber” & the rift unless its >10km…….as there are no quakes to connect flow of magma

    further more, a small drop in pressure 10km…. as this is where the hot fresh pressurised magma came from ……way down deep…..to cause/fill the rift and the eruption ……at this depth there is magma “everywhere” as it rises from ……way down deep… along the huge MAR fault in plumes……. connecting in a de-facto way …..to all the volcanism along the MAR

    g added to linky #Gr

          • I’ve had that issue occasionally also if I started to post a reply, then used “cancel reply”, then tried to post somewhere else the original post would keep going in everwhere and not what I wrote in each new location. It’s a weird bug with wordpress where I’m guessing the canceling doesn’t delete the javascript generated form attached to the first comment and instead submits it instead of the correct reply.

            • Hmm, and for some reason the “reply” to post is instead posting at the top level??? This is new today. DT, you broke wordpress! 😀

            • Well, not really, one of his posts got jumped on by the automatic systems and required dragon intervention to correct the comment flow.

              We keep a pet bandersnatch down in the dungeon and sometimes it gets loose of it’s chain. In this case, it took a bite out of one of DT’s posts.

    • Re “No quakes in the centre of the caldera”. If you are proposing this against the opinion Ian F has been canvassing today, I didn’t get the impression from his posts that he thinks the Vyazmensky gif is an exact representation. I took it that he thinks it shows the way in which the collapse caused by the emptying of the magma chamber occurs.

      On the other hand, your claims about harmonic tremor do, I think, count against his proposal, though I don’t think his account of what’s going on is not *part* of the story.

      • Yes, am57, you are complelty correct, it was an illustration what happens to the walls, not what is happening in the core

        Just to clarify

        I have also suggested there is magma movement within the caldera. There has been tremor, just not very much and never sustained very long. Look at the DYN plot, when magma was moving through the dike, there was sustained tremor until it broke out to the surface

        What I do not see any evidence for is a large influx of magma rising in the caldera

        • Clear your mind must be, if you are to discover the real BB mystery :-)…… extreme visualization & loosening your minds shackles……… 🙂
          Forget the “plug” & “multiple stacked chambers” ……. the caldera floor is just the top of a hardened 8km x 11km magma lake….. a very simplified toon of Bárðarbunga:

          A influx of 2 plumes total 4km3 of magma is <1% of the BB "magma chamber"…… it slowly rises & displaces colder mush…….put 1% more hot water in a bath you couldn't see/tell/feel the difference 🙂

          • …….. it is simply an impossibility for the 500km3 open at depth BB “magma chamber”……….to empty

          • DT, “the caldera floor is just the top of a hardened 8km x 11km magma lake” – where does that data come from, can I ask? Maybe I missed a memo, but AFAIK even IMO and EIS aren’t claiming to know the subglacial structure of BB with any certainty?

  20. 5) Since the BB “magma chamber”is open at depth……….way down deep… ….there is no need for /nor can the colder less buoyant less pressurised crystallised mush & magna descend at all to a depth of >10km…. as this is where the hot fresh pressurised magma came from ……way down deep…..to cause/fill the rift and the eruption ……at this depth there is magma “everywhere” as it rises from ……way down deep… along the huge MAR fault in plumes……. connecting in a de-facto way …..to all the volcanism along the MAR

  21. I re read the interesting post made by DT, the translated interview with Ari Gudmundson.


    I find the idea that two events (Holuhraun and Bardarbuga) are connected on a large oblong magma chamber under the riftzone at depth of 15 – 20 km plausible. The squeezed b- ‘plug’ by the Hreppar plate and the ‘problems’ with the estimated erupted lava do fit. We might have been mislead by the Earthqauke activity in the first period, when it looked like a dyke originated in B. and finally erupted at Holuhraun. Maybe at first the connection existed, but the dyke soon connected to another source, that “oblong shaped” chamber.

    I didn’t read anything about the last remark made in the last paragraph before:

    “The (Holuhraun) eruption could go on for years. Let´s not forget, the Surtsey eruption lasted four years. And this is a similar thin flowing primitive magma. Let´s say, if this goes on for three or four years, then we´ll have a beautiful shield there (in Holuhraun). What is interesting about this magma, it´s very homogenous, and previous magma coming from the Bárðarbunga system is amazingly homogenous, although you have two types, one in the south part, one in the north part…”

    Why is it amazing that the magma from the Bardarbunga system is homogenous?
    And , the two types of magma, how can they be characterized to consider them as two type? Can someone point out what the difference between them is?
    And then, could the difference plae for the consideration of two different paths of magma, one to Holuhraun and one to B?

    No expert, probably clear to you …. 🙂

  22. Hi All,

    A timelapse from the Mila webcams pointed at the Holuhraun fissure eruption from the Icelandic Bardarbunga volcano.
    It covers the 30th of November to 2nd of December 2014,though chronological there are many jumps.
    The interval between each screenshot was 10 seconds with 25 frame per second.

    The storm that passed along Iceland is noticeable on the fast moving thick clouds. At night business as usual with the vent blazing along.

    All music by Boards of Canada: “Collapse” and “Sundown”.

    I will not make as many timelapses anymore as usual, so if you want to be certain that you have a memory of a certain day do not rely on me. 😉
    (I don’t plan to stop, but cannot cover every day anymore)

  23. Thanks folks – this is really intense discussion with lots of info!

    One minor observation from a clot like me: I wonder if the lack of earthquakes in the centre of BB’s caldera highlighted by DT (after the Alex Vyazmensky collapse diagram) might be because the central ‘plug’ is already largely a warm mush with a cooler, plastic top. Yes, it is collapsing and fragmenting as per Alex Vyazmensky’s diagram but the majority of the lower part is like a tough hot plastic, not cold and brittle. This suggestion also might offer reasons for the minor hot-spot observations under the ice. Therefore the reason we don’t get a major caldera blow-out is because Holuhraun is currently taking the pressure out of the system and the ‘lid’ is 70% semi-ductile re-melted as it sags. Any uprising magma may be adding to the ductile plug.

    But at the edges of this soggy plug, the colder brittle rock gives seismic activity. The long term outcome is either an eruption in BB, or a collapse of the nothern caldera wall into the mushy plug, also triggering eruption. Or IMO’s first thought is right and the whole lot just grinds to a halt.

    Just as an aside, I’m personally not a fan of the idea of the rifting process pinching the top of BB. To my mind that goes against the whole spread of the MAR. If the general hot spot under the area is moving around and kicking the micro-plate, then these may be causing a temporary squeeze in BB but this will change swiftly. That’s a theory and I’ll just park it there for people to set fire to it and warm their hands over the flames of my burning ego!

    Now, I add the proviso that these are the ramblings of an ageing Englishmen after a few tins of his favourite English cider. I’m not even an expert. I’m so dumb even my feet have a higher IQ than my brain! 🙂


    • I agree that the seismic signal you see within the plug is not going to be comparable to the seismic signal you get from fracturing in the walls, not necessarily because the plug is warm and ductile (though it might be in parts) but because, like most calderas, it is probably already pretty fractured. We see similar attenuation of seismic signals in the Taupo volcanic zone which is composed of volcanic infill (and a lot of that non-welded ignimbrite). Along the edges of the zone where the crust still has its integrity earthquakes ring like bells up and down the country. Go a few miles to the west and you hardly feel them.
      I imagine this is what is happening here too. The large quakes are happening in parts of the edifice where there is still a strong degree of coupling.

      • Beauty! It is on the edge of a large volcano, Elysium Mons. The flat area surrounding it seems covered by sediment which left only this cone sticking above it. The area is (was) volcanic, but no evidence for eruptions here. The ridges would be consistent with ice evaporation. Very circular. Picture below is from the larger area (not sure exactly where the cookie is but somewhere around the marker – could be the mount below the marker). Note the debris surrounding the impact craters to the right. That show a lot of ice which was partly melted by the impacts

    • Most strange! looks like someone stuck the nozzle of an intergalactic vacuum cleaner to the surface. No radial signs of impact or anything like that, just an absence of sediment on top of what looks like pahoehoe flows.

  24. From Yesterday’s fresh news: Piton de La Fournaise volcano may enter a new eruptive phase:
    “The Piton de la Fournaise Volcano Observatory again recorded since December 3 significant earthquakes accompanied by localized deformations in the crater.
    Since Thursday morning the frequency and intensity of earthquakes has increased (5 earthquakes ever recorded at 9:30 am with a high magnitude) and recorded deformations are increasing. This resumption of activity can cause collapse or an eruption within days or weeks.
    After technical opinion of the Observatory, the Mayor of Reunion triggers the level of alertness of the device * ORSEC specific “Piton de la Fournaise volcano” this Thursday, 4 December (from 10:00).
    Consequently, the mayor asked hikers accessing the upper part of the enclosure of the Piton de la Fournaise to stay on marked trails. “We see phenomena greatly fluctuating ,” says Nicolas Villeneuve. Impossible to predict whether an eruption will occur or not in the coming days. “All we know is that today there is an increase of seismicity,” the head of the Volcanology Observatory.
    14 earthquakes were recorded in the last hours. 5 were recorded this morning, one felt by hikers. Magnitude 2.9, “is stronger than all the earthquakes recorded since 2007,” said Nicolas Villeneuve.”
    Translated with the help of Google
    We haven’t seen an eruption from Piton since June, 2014. Will we see another Hawaiian type eruption any soon?

  25. So do these barely visible clouds of steam indicate the lava front in the river channels is moving again?

    roll on daylight

    • It hasn’t stopped steaming, though there seems to be less steam than there used to be.
      The left (south-facing) camera also showed the landscape lit up – I think it’s that moon again – full, this time…

  26. IMO have reported that they overflew the caldera yesterday and are processing the data collected and that a helicopter is flying in today to fix the GPS.

  27. Pictures from IMO’s overflight yesterday (4th Dec) – including a couple of good ones of the lava edge (but not the waterfall). It is worth going full-page, then right-hand-mouse button, choose “view image” and click to expland.
    (Disabling the link because it might try to load everything).

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