Iceland in ashes

I had never seen the Manchester sky so blue. The usual milky white which goes by the name ‘Manchester sunny day’ was gone, transformed into an azure experienced mainly during distant holidays. Great Britain of course has a bit of a reputation. Already the Romans wrote that “the atmosphere in this region is always gloomy”.

But Manchester isn’t always that bad. At least, blue skies do occasionally happen, in between the rainy days. But that was before the modern days of air travel. Nowadays, a day here may start out clear, but quickly lines of white cirrus form, and expand until they cover most of the sky. Aircraft contrails have changed our world: 10% of cloud cover over the North Atlantic is now due to us. But suddenly, the BA cirrus was gone and the sky showed us its pre-flight colours.

The cause was out in the North Atlantic. Precisely on the flight path between Europe and the US, a volcano had begun to act up. After a period of stutterings, Eyjafjallajökull exploded on 14 April 2010. The next day, the ash cloud became dangerous to plane engines, and for five days the air space was closed – and the Manchester skies turned blue.

The ash cloud of Eyjafjallajökull. Source: wikimedia

Eyjafjallajökull is a fairly minor volcano, at least for Icelandic standards. But it erupted explosively, and the power of volcanoes should not be underestimated. A VEI-4, which Eyjafjallajökull was, can eject ash to 8-10km altitude where jet stream winds can spread the ash around. It did, and the ash rapidly affected northern Europe. Economically, Eyjafjallajökull became a disaster. The flight ban caused an estimated cost of 1.8 to 2.4 billion dollar (incidentally, it also made this the first carbon-neutral volcanic eruption). It showed us the vulnerability of the transatlantic links.

But how common is such an eruption? This was the only such event in Iceland in a century of flight. Were we lucky? Or was this a once-in-a-life-time event? Let’s do some digging and clear the dust from the ash.


No one likes ash. Lava, bright red and pitch black, impresses us; especially at night it has a beauty that belies its destructiveness. Ash, in contrast, gives a deadly grey hue to the landscape. It covers everything, falling like snow in thick flakes. Vegetation is killed and houses collapse under the weight. Water will collect it, and a torrent of wet ash can form lahars. Ash has an ugly side.

In large eruptions, the ash clouds can become fully opaque. Within ten kilometer or more from the volcano, day turns to night as the light goes out. It is not like ordinary cloud. Sunlight has no problem getting through clouds: the water droplets scatter the light but do not absorb it. That is why you can still see on a cloudy day and why mist seems luminous. I once was in a snowstorm with lightning. Every time the lightning came, the swirling snow would shine with the light coming from everywhere. It was quite an experience. But mix a bit of dust in with the cloud and things grow dark. As I write this England is preparing its annual experiment with this. Bonfire night, November 5, is the traditional time in the UK for firework displays. Initially, the fireworks are brightly visible, but after a while the smoke from the displays begins to obscure the view. It can take a full day for the smoke to be fully dispersed. And when the smoke mingles with fog (this is the UK, after all), visibility goes to zero. It is best to stay off the roads during bonfire night: when people drive at normal speed into a fog bank and suddenly visibility turns out to be less than a meter, accidents can happen. Go on, and you hit what ever is in front of you. Stop, and the car behind you slams into you. Smoke is bad news. After all these years, Guy Fawkes still kills.

The impenetrable darkness is a common feature of major eruptions. Here is an example from Krakatoa, a description from captain Watson of the British ship Charles Bal:

“At 11.15 there was a fearful explosion in the direction of Krakatoa, then over thirty miles distant. [..] At the same time the sky rapidly covered in; the wind came out strong from S. W. to S., and by 11.30 A. M. we were inclosed in a darkness that might almost be felt; and then commenced a downpour of mud, sand, and I know not what, the ship going N. E. by N. seven knots per hour under three lower topsails. We set the side lights, placed two men on the lookout forward, the mate and second mate on either quarter, and one man washing the mud from the binnacle glass. We had seen two vessels to the N. and N. W. of us before the sky closed in, which added not a little to the anxiety of our position. At noon the darkness was so intense that we had to grope our way about the decks, and although speaking to each other on the poop, yet we could not see each other. This horrible state and downpour of mud and debris continued until 1.30 P.M., the roaring and lightning from the volcano being something fearful. By two P.M. we could see some of the yards aloft, and the fall of mud ceased; by five P.M. the horizon showed out to the northward and eastward, and we saw West Island bearing E. by N., just visible. Up to midnight the sky hung dark and heavy, a little sand falling at times, and the roaring of the volcano very distinct, although we were fully seventy-five miles from Krakatoa. Such darkness and such a time in general, few would conceive, and many, I dare say, would disbelieve. The ship from truck to water-line was as if cemented; spars, sails, blocks, and ropes were in a horrible state; but, thank God, no one was hurt, nor was the ship damaged. But think of Anjer, Merak, and other little villages on the Java coast!”

The ash deposit near a major eruption can become meters thick. The larger particles do not travel very far as they are too heavy to be carried by wind. Smaller particles go further and these are actually more opaque. They still can’t travel as far as the gas, but a large eruption can deposit centimeters of ash hundred of kilometers away. Toba, in Indonesia, managed to deposit 9 meters in India, although this was after water had washed the ash into valleys and thickened the layers; the original layer was probably more like tens of centimeters.

But ash also has a good side. It kills vegetation, but also fertilizes the ground. Over time, the land will recover and plants will grow with more vigour than before, on an enriched soil. From the green and colourful peat of central Iceland to the highlands of central Africa, volcanic soil brings life. Coffee is a well-known beneficiary. The best coffee (Arabica) grows where the volcanoes are. Ethiopia, Guatemala or Kona: this demanding plant lives on ashes.

Hither and tither

Ash follows the wind. The initial explosion can give a narrow ash trail pointing down-wind. After some time, the winds change and the ash is blown in a different direction. Different altitudes also have different wind speeds and directions. This causes the plume to bulge into a spreading cloud. But it remains loath to travel against the wind. Even Toba, which to the west devastated an area the size of a continent, left much less destruction to the east.

A typical Icelandic low

Iceland is not known for its stable weather. It seemingly changes every 5 minutes. Still there are patterns. South of Iceland is a highway for low-pressure systems, on the way to Scandinavia. It gives rise to something called the ‘Icelandic low’: a semipermanent region of low pressure, really a succession of one such system after the other, where the average pressure is 10-15mbar below that of standard sea level pressure.

This highway is more pronounced in winter than in summer but it remains a common feature. Because of it, the dominant wind direction in Iceland is east to northeast. Icelandic ash will therefore at first often travel towards America. While doing this, it also tends to wrap around the Icelandic low and once it finds the right place, will be carried towards Europe. Iceland is well placed to cause maximum havoc. But during the Eyjafjallajökull eruption, the wind was from the north or northwest. This slightly unusual situation made the impact on Europe much worse. Rather than cutting transatlantic routes, the ash cloud went directly for the intra-European air space. And it did so during the Easter holiday season.

Frequency of wind direction, based on data from 1930-1960.

Ash and engines

The part of an airplane that is affected by volcanic ash is fairly important: it is the engine. The silica particles have a melting temperature that is well below the temperature found inside the engine. The engine sucks in the air, heats it, and expels it from the back. That is not good thing to do when there is ash. The ash partially melts, sticks to the turbo blades, and re-solidifies. Larger particles (1 mm or more) are more prone to doing this. The ash cover increases the compressor discharge pressure, which may cause the engine to surge and loose thrust. This has happened on occasion. As the engine turns off, it cools, and when it cools below the glass transition temperature, the frozen ash becomes brittle. After a while it becomes possible to turn the engine on again as some of the ash fragments and breaks off. Hopefully by that time the airplane is still at a safe altitude.

Eyjafjallajökull spewed its ash mainly to 4-6 kilometer height, with occasional bursts to 9 kilometer. That limited the area that was affected as it made the ash drop down faster. Planes should have been able to find routes around and over it. But we lacked the technology to see where the ash cloud was. It consisted mainly of glassy silica, a material that is transparent to radar (radomes tend to be made out of fibreglass for that reason). Thick clouds can be seen in satellite images, but thin ash clouds may not be.

Because of the major impact of the Eyjafjallajökull eruption, the rules on flying through ash clouds have been relaxed since 2010. Charts now identify three levels of ash concentration: cyan (low contamination), grey (medium contamination) and red (high contamination). It is now allowed to fly through zones of low contamination. However, even though the aircraft may not be endangered, the engines can still suffer damage. Ash affects different engines differently, but without dismantling the engine, it is impossible to know how badly it has suffered.

Airplane routes as shown by satellite measurements of NOx emissions. The red triangles show the location of potentially eruptive volcanoes. Image from Prata 2008, Satellite detection of hazardous volcanic clouds and the risk to global air traffic, published in National Hazards.

Ash in bogs

Ash does more than cut our light and damage our planes. We have already mentioned how it fertilizes distant places. An eruption can give a dusting of ash across a continent. Some of it falls in places where plants can’t get to it: icecaps are one such place, but lakes, swamps and peat bogs also qualify. The ash comes down and becomes included in the sediment layers or the annual growth. Later, you can dig down into a peat bog and find layers with ash in it, a safely stored record of past eruptions.

Icelandic peat

There is a second advantage to the bog-loving scientist. Neither lava nor ash can be carbon dated. It lacks suitable carbon. Lava flows can only be dated by digging out any vegetation it may have covered and carbon dating that. But often there is no such vegetation. Find the ash in a peat bog, and finding carbon will not be a problem. The peat is full of it.

And finally, the composition of a tephra ash shard shows its origin. Every volcano has slightly different ratios of various elements (and to make it more complex, this can change over time). This makes it possible to identify which volcano caused which tephra layer, and to show which tephra layers in different locations came from the same eruption. What is there not to like about bogs?

Tephra layers are sometimes visible by eye. But more often, the fragments are too small and few to see: this is called cryptotephra. A detailed analysis takes time consuming research. A common method is to cut the peat into small segments, burn it for several hours at high temperature, wash the remains, centrifuge them for 10 minutes, extract the bottom layer and view through a microscope. Now start counting the shards. Science can require patient work.

This brings us back to the topic of the post. If we can find out how many tephra layers there are in the peats of northern Europe, we know how often an ashy eruption similar to Eyjafjallajökull happens. This is more difficult than it sounds. It means looking through many different bogs and lakes, since ash disperses into different directions. Tephra from the Askja 1875 eruption, for instance, ended up in Sweden while tephra from Öræfajökull 1362 is found in Northern Ireland. Hekla 1104 is found all over Ireland and the Faroe Islands. The so-called Glen Garry tephra, of unknown origin and dated to around 100 BC, is found in various locations in Scotland, Cumbria, and Northern Germany. Sampling one location just won’t do.

Lawson and collaborators (2012, published in Quaternary Science Reviews 41) created a list of tephra layers that are present in at least three different locations. The most recent one in their list is Hekla 1947, and the oldest one is from around 5000 BC. Of the 22 layers that they find, 8 come from Hekla. Surprisingly, 3 are from Torfajökull. One of the layers is not from Iceland: it is attributed to Jan Mayen. The plot below shows where the tephra is found. The size of the circles indicates how many of the 22 layers are found at each site. Ireland is doing particularly well. The Faroe islands also catch many of the eruptions. Elsewhere in Europe the coverage is more patchy.

From Lawson et al, 2012, Quaternary Science Reviews 41

This study was followed by a paper by Watson et al., published in 2017 in the journal Earth and Planetary Science Letters, Volume 460. It is largely the same team that presented the previous work. Here, they greatly extend the number of sites in Europe searched for tephra layers, and also added in eruptions with documented ash fall outside Iceland but where tephra has not been recovered from peat storage.

Watson et al. find that over the last 1000 years, 24 ash falls have occurred in Europe or the Faroe. Of these, four are known only from historically documents but lack tephra grains (1755, 1660, 1625 and 1619). The list below is a shortened version of their list where I have removes ones that may be double counted. That leaves me with a minimum of 21 events over the past 1000 years.

2011 Grímsvötn ashfall
2010 Eyjafjallajökull ashfall
1947 Hekla Dacitic-Andesitic
1875 Askja Rhyolitic
1800 Basaltic (1728-1880) Laki?
1755 Katla ashfall
1700 unknown (1650-1750) Dacitic
1693 Hekla Dacitic-Andesitic
1660 Katla ashfall
1650 unknown (1600-1700) Rhyolitic 
1625 Katla ashfall
1619 Grímsvötn ashfall
1510 Hekla Dacitic-Andesitic
1477 Veidivötn Basaltic
1400 Jan Mayen (date uncertain; Azores?) Trachyte 
1362 Öræfajökull Rhyolitic
1250 (Rinjani?) (date uncertain) Rhyolitic
1158 Hekla Dacitic
1157 unknown Rhyolitic
1104 Hekla Rhyolitic
1000 unknown (date uncertain) Rhyolitic-Dacitic 
900 unknown (possibly several eruptions) Rhyolitic
871 Veidivotn Basaltic
860 Mount Churchill Rhyolitic
721 Snaefellness Trachy-Dacite

(The Greenland ice cores add a bit more. It has fewer tephra layers (but more sulphate layers) but it includes some grains from much larger distances, such as Rinjani and the 1453 eruption. Tephra from Laki, Eldgja and the so-called settlement layer from 870 AD are found in Greenland.)

Over the past 7000 years, a total of 84 ash clouds in northern Europe are identified by Watson et al. The originating volcano is identified for 46 of these, 15 of which are Hekla. Six events appear not to be Icelandic, based on the composition: four are from Jan Mayen, one from the Azores and one is from the 853 AD eruption of Mount Churchill in Alaska.

From Watson et al., 2017, Earth and Planetary Science Letters, Volume 460, 41

The plot shows the various origins. The vast majority of the events come from Iceland’s eastern volcanic zone. Of the remainder, and perhaps surprisingly, Snaefellnes is the most productive. Hekla has been the most prodiguous and consistent producer. Katla has also been active throughout the period studied. Grimsvotn is a major producer over recent years but there is only one older tephra layer known from it. Of course, it can be difficult to assign tephra to a volcano if that volcano rapidly changes its magma composition. The ‘unknowns’ may hide some of the knowns.

There are obvious absentees. No European tephra has been found that is attributed to Laki or Eldgja. (There is one find of basaltic tephra with a possible date range that overlaps with Laki.) Basaltic tephra is in fact very rare in Europe. The reason is clear: it takes an explosion to lift ash high enough to reach Europe, and effusive eruptions don’t normally manage this. It is easier for ash to reach Greenland, which is closer and in the direction of the prevailing winds, and this is why grains from Laki and Eldgja are found there. The dead zone is effusive and therefore unlikely to cause European ash. Bardarbunga is completely missing. It erupts through fissures and this takes the pressure off – it tends to avoid explosions and keeps Europe clean. Katla is a different beast: it does do fissures but also happily covers Europe in ash through explosions. The Vedde ash, which was not included in the study by Lawson because of its age, is the most widespread tephra event in Europe; it probably came from Katla.

Comparing the plot above with the VC mammoth map of Iceland shows that most tephra comes from the southwest side of the dead zone. For tephra, southwest is best. This is the region where Iceland explodes most frequently. (Incidentally, it is also the region with the highest snow fall.)

How large does an eruption need to be to cause ash in Europe? Over the past 1000 years, Iceland has had 36 eruptions of VEI 4 or VEI 5. Not all of these were explosive: a peculiarity of the VEI scale is that it uses volume rather than energy to measure explosiveness, and this means effusive eruptions intrude into the list, often in the top position. If we exclude all the mafic (basaltic) eruptions, there are 18 eruptions left. Of these, 13 have caused ash in Europe. In contrast, not a single VEI 3 eruption has been identified in the tephra record. (A disclaimer here is needed, as the origin of some of the tephra deposits remains unknown.) And the VEI 5 eruption of Hekla in 1104 left tephra in no fewer than 27 different sites. Size matters.

Watson et al. conclude that a silicic eruption of VEI 4 or (rare) larger has a 73% chance of causing an ash cloud over Europe. More precisely, their data suggests that to affect Europe requires an Icelandic explosion of 0.2km3 or more.

Hekla 1947 (

What about the exceptions? Three of these stand out: Hekla in 1766, 1597 and 1300. All were large enough to reach Europe: 0.3-0.5 km3. In 1766 and 1300, the dominant air flow was to the north and if the eruption was brief, Europe may have been saved by wind. But in 1597, the ash did go southward and it is not clear why no tephra from this eruption has been identified in Europe. It is just one of those things.

And what about the unidentified layers? Each of these tends to be found only within a single region. It may be that these do trace smaller, VEI 3, eruptions. We need a scientist with a lot of patience to analyze more bogs!

The question that we really would like to answer: what is the chance of this happening again? The next time we fly across the Atlantic, what is the risk of not being able to go back due to an uncooperative volcano? The relaxed flying criteria since 2010 means that an eruption will not have as bad an impact as Eyjafjallajökull had. But a lesser impact would still be costly.

If we assume that it takes a silicic VEI 4 for this to happen, we can expect European travel chaos to happen once every 55 years. If only 73% of these do so, we may have to wait a bit longer, 75 years on average. If, on the other hand, each tephra layer indicates a flight disruption event, it would happen as often as every 45 years. Pick your choice!

Ash in waiting

Volcano in waiting

But the signs at the moment are that we won’t have to wait that long. Hekla is quiet – but elsewhere in Iceland, Öræfajökull is building up to an eruption. It is still early days. The earthquakes only started during 2017. But the signs are there: an increasing number of earthquakes (at the rate of this week, November 2018 would top the previous record, set in August), inflation, and increasing heat at the summit. Öræfajökull erupts infrequently but when it does, it can really go for it. An eruption will be rhyolitic, ashy because of the ice cover, and it may well reach VEI 4 in strength. The build up to a volcanic eruption tends not to be regular. Swarms can be intermittent. The Öræfajökull earthquakes may well die down again, at least for a while. But once the process is started and a conduit begins to open, it is hard to stop an eruption. Somewhere in the next decade, Öræfajökull is likely to explode spreading its dust in the wind. And the planes will stop flying.

Albert, November 2018

Dust If You Must (Rose Milligan)

Dust if you must, but wouldn’t it be better
To paint a picture, or write a letter,
Bake a cake, or plant a seed;
Ponder the difference between want and need?

Dust if you must, but there’s not much time,
With rivers to swim, and mountains to climb;
Music to hear, and books to read;
Friends to cherish, and life to lead.

Dust if you must, but the world’s out there
With the sun in your eyes, and the wind in your hair;
A flutter of snow, a shower of rain,
This day will not come around again.

Dust if you must, but bear in mind,
Old age will come and it’s not kind.
And when you go (and go you must)
You, yourself, will make more dust.

75 thoughts on “Iceland in ashes

  1. I remember Eyjafjallajökull well… My flight from Stockholm to London was canceled and I had to drive from airport to airport to keep traveling. 20 hours including the ferry – not too bad!

  2. The importance of the wind is readily illustrated by Grímsvötn. A few years after Eyjafjallajökull finished, Grímsvötn erupted with greater vigor and had little effect on air travel. It’s ash cloud went to the north east.

    Note: “Greater Vigor” → Grímsvötn did in a few hours what Eyjafjallajökull did in it’s entire run.

  3. I just added some notes to the unknown eruptions:

    1700 unknown (1650-175) Dacitic *** Around 1700, Bardarbunga erupted
    1693 Hekla Dacitic-Andesitic
    1660 Katla ashfall
    1650 unknown (1600-1700) Rhyolitic *** I see two candidates: In 1655 a large unidentified eruption occurred in Vatnajokull. In 1630, there was also a large eruption in the Azores (Furnas)
    1400 Jan Mayen(date uncertain) Trachyte *** Around 1430 a VEI5+ caldera-forming eruption occurred in the Azores, I am sure that its ash would have reached the British Isles
    1362 Öræfajökull Rhyolitic
    1250 (Rinjani?) (date uncertain) Rhyolitic *** I don’t think Rinjani ash would have reached Europe, despite being an enormous eruption. A large Vatnajokull rifting eruption known as Frambruni might have been the culprit
    1158 Hekla Dacitic
    1157 unknown Rhyolitic
    1104 Hekla Rhyolitic
    1000 unknown (date uncertain) Rhyolitic-Dacitic *** Another ashy Katla eruption around this time
    900 unknown (possibly several eruptions) Rhyolitic *** Eldgja would be a likely candidate!

    *** the deadzone is not as effusive as most people think. The Veidivotn and Vatnaoldur deposited very thick ash layers in Iceland, so they may have deposited some ash in continental Europe. Most ash was basaltic from Bardarbunga, but some was rhyolitic from Torfajokull. Edlgja was also quite ashy. Laki was much less ashy, but is known to have spread an enormous sulfur cloud over Europe.

    • These are good points. I found one record assigning the 1400 ash to the Azores. This is not settled but plausible. The 1258 Rinjani ash is found in Greenland (it is rare for tropical ash to get that far but a VEI-7 will do it), and so finding some in Iceland is possible. Eldgja is not rhyolitic but its deposits may be hidden among other eruptions.

  4. just got done dusting…. eruptions may pass but dust stays…. hadn’t heard that rendition before… we are indeed, stardust in the wind…. and the setting sun changes my volcanic dusty windows into gold stained glass. Enjoyed this one… Best!motsfo

    • Speaking of stardust. Any element of greater atomic weight than Iron is almost certainly a product of supernova action.

  5. It would be interesting to know if there are any layers from eruptions from volcanoes in mainland Europe…

  6. Aviation emissions can be controlled, not so volcanic emissions. or solar emissions. The sky over Manchester and my garden has certainly changed over the last 20 years. The science discussed in the last post left my small brain reeling. The prospect of Öræfajökull erupting makes my rainbow coloured 21st Century anti static feather duster look worse than useless and now I am ruing the day I chose an electric oven over gas. Weeks of not being able to bake cakes and creating casserole dishes from left overs is a scary prospect Even worse is the thought of what devastation will be caused to the generation that is now so reliant on the mobile phone.Added to that scenario is the effect of a volcanic winter. .As has been mentioned before, the wrong shaped snowflakes or autumnal leaves throw the UK into chaos. I foresee a situation in the UK that will put the turmoil of Brexit into the shade. Imagine if all these events happened at the same time! Time for a soothing cup of coffee to settle my blood pressure. Thank you Albert fo another stimulating post. PS I identify with the writerof the poem and Mots’ deeply philosophic and poetic approach to that chore that I do not practice daily.

    • Don’t rue the day make a roux! It goes well in pretty much any stew.

      BTW, I keep a Dutch Oven around just in case. As long as you can get some sort of fire, it works.

      As for the “next generation?” I guess they should have paid attention. You can lead a horse to water, but you can’t make him cook a roast.

    • Also remember those days. Booked flight from Gothenburg to visit daughter in north of Sweden. Flight canceled so took the train. Experienced the same as described by Carl..

    • Nice to hear from you! And no worries: Öræfajökull will not cause a volcanic winter. Only Laki and Eldgja came close to that. The next volcanic winter will also be unable to compensate for the amount of global warming: we are now a full degree over pre-industrial and a typical volcanic winter cools the world by less than that. It is fun though to try to predict which volcano will be the next VEI 6+. My bet is that it will be one we have never heard off. It is less fun to think about the impacts it would have.

  7. Eyjafjallajökull was an old magma… old magma that sat in the throat of the volcano. It erupted an andesite.
    Thats why the ash had souch a grey colour. Grimsvötns 2011 basaltic ash is black… while Eyjafjallajökull 2010 was a sillica richer grey andesite.
    Fimmvördhals was the fresh intrusion that pushed out and made the old magma in Eyjafjallajökull erupt.
    I buyed ash from Grimsvötn and Eyfallajökull in Volcano House Reykjavik and these ashes are very very diffrent! One is matt dull steel grey and very fine… the others is picth black and quite coarse.

  8. I remember the day vividly.

    I was sitting in Brussels pondering how to get back home. In the end I got the last available rental car and farted homewards to Denmark in (if memory serves) a very puny 3-cylinder Opel that made 100km/h. Driving in a miniature car slowly on the German Autoban is a frightening experience indeed.

    As I rode the following train up north I watched the air take on a definite golden hue that I have never seen either before or after that.

    • Remeber that eruption in its late stages.. when it was large andesite strombolian burps in the summit crater.. with lava bombs the size of houses. Each burp had a shockwave and cannonball like sound blast. Thats violent strombolian activity just before Eyfajallajökull went silent

    • Likley was massive gas slug flow in the conduit at that stage.
      Each bubble coud have reached 60 to 100 meters across and violently exploding around 14 times every minute.. I never seen souch strombolian action before!

  9. Hot ashcloud from Eyjafjallajökull.. zillions of hot glass particles glowing.
    This is the same dynamics with the glowing sooty clouds from an oil fire
    All glowing hot tiny particles one glass particles ( volcano ) the other glowing unburnt soot.

  10. Gorgeous shot of constant vulcanian burps from Eyjafjallajökull in 2010
    glowing hot ashclouds. The glacier water helpt it to make it more exploisve… but the high viscosity of the magma and gases help to increase explosivity too

  11. Andesite bombs flying in the air 2010. Each of these coud be the size of a large bus
    They are in direct sunlight.. the deformed surfaces suggest they are molten.
    Had this been at night… the bombs woud glow bright orange.. with no sun to outshine them.
    Here are more photos from Eyjafjallajökull 2010

    • Wow! Thanks for these and the link! Awesome. I wish I could have stood where those guys stood, although I think I’d want a hard hat the size of a small McDonalds restaurant.

      • There are tons of spectacular photos from the Eyjafjallajökull eruption. Apart from ash and volcanic bombs, Eyjafjallajökull also produced a lot of volcanic lightning. Try an image search for “Eyjafjallajökull lightning”. I reckon you will find the results most enjoyable.

        One of the most famous images also exist in a version with a photoshopped cat…

  12. Strong fountaning of viscous basaltic magma at Fimmvördhals 2010
    This is where the Eyjafjallajökull show started. This fissure eruption had quite high viscosity for a basaltic lava and made strombolian eruptions and huge lava rivers of Aa lava. Looking alot like an Etnean eruption beacuse viscosity is the same.
    This is much diffrent from the fluid hawaiian Holhuraun in 2014 that was much hotter than this

  13. Big channelized river of Aa lava flowed down fimmvörduhals
    It then cascaded over drop off in a huge shower like fall of lava lumps forming piles of hot rocks

  14. Another fun shot from 2010 when the lava flowed over steep drop offs
    tumbling down into cascades of hot rocks and glowing soft boulders
    it all landed on a glacier and caused big steam explosions.
    The deposits below became huge glowing piles.
    Fimmvörduhals was infact not a very large lava eruption but eruptive rates was pretty high.
    Each one of these lumps coud be the size of a large bus.

    • When Fimmvörduhals vent began to resemble a blowtorch, I figured something was up. Within a couple of days, a subsurface finger of magma shot across to the summit chamber and it went boom.

  15. yes they are awsome… its so sad I missed it…
    I wish I was there sourrounded by falling lava
    magnificent….. it is! photos by Martin Rietze
    Nothing else is better than a raging volcano
    I loves it… loves it and there is no limit how huge I wants it.
    I think its time to re – awake siberian traps

  16. Here is an Aa lava flow that was erupted by Fimmvörduhals
    Aa lava is the more viscous flows in fluid basaltic activity and is generaly typical of high eruptive rates and often feed by huge fountains and very quickly moving channels.

    Aa lava flows move quite slowly and the crust breaks into rubble called clinker that tumbles down the moving flow front.The plastic flow core is hidden beneath this crustal rubble.
    It advances like a tank caterpillar wheels. In cross section an Aa lava flow haves an outer rubble layer, a hard dense flow core that show some cooling joints and a lower rubble layer. The lower rubble layer is the falling clinker that the flow have overridden. Aa flows can be very massive and crushes everything in their path.

  17. While O.T., here’s a recent and very interesting paper/letter detailing some extraordinary observations of the first confirmed interstellar visitor to our solar system, Oumuamua. Since it’s first discovery in 2017 following a path that led to interstellar space, Oumuamua accelerated during it’s passage through our Solar system in such a way that defies any “standard” explanation were it an asteroid or a comet. If it was a comet with outgassing being the principle energy source for the acceleration, then there should have been some type of gasseous chemical signature…but there there was absolutely nothing detected…despite being only 0.25 a.u. at it’s closest approach to the Sun and unusually bright (which argues against the asteroid theory as well, since asteroids are dark and don’t typically accelerate themselves). So, if it wasn’t a comet with jets, then what would be causing the acceleration? The Solar Wind’s effect on a solid mass this size would be negligible considering the magnitude of acceleration that was measured, so that leaves only Solar Radiation Pressure as the only likely explanation for Oumuamua’s acceleration. However, if Solar Radiation Pressure was indeed creating the excess acceleration, then to account for it’s brightness, the structure of Oumuamua has to be sub-millimeter in thickness over a huge area! And, given that Oumuamua’s light curve shows it to be rotating (6-8 hr. period), how something so thin could maintain it’s structural integrity despite the tinsel/centrifugal stress and tidal forces requires a material with a composition that is currently unknown in nature.
    So, if this thing is indeed an ultra-thin sheet of some type of mass less than a millimeter thick that is capable of sailing on Solar Radiation, what’s the possibility that Oumuamua is of alien design? An intriguing possibility that the authors actually get into..something we don’t ordinarily see in research papers like this.
    Anyway, with Oumuamua now well on it’s way to who-knows-where, we’ll never really know whether this thing was artificial or not, but the data is compelling enough that regardless, this thing was unlike anything mankind has seen before.

    Shmuel Bialy and Abraham Loeb
    Harvard Smithsonian Center for Astrophysics, 60 Garden st., Cambridge, MA, 02138
    Draft version November 1, 2018

  18. I remember having seen the eruption plume from Lady E/Eyjafjallajökull with my eyes. Though it was from quite a long ways away from where my flight was over the North Atlantic, I could still easily see it. I was on a Thomas Cook A330-200 from Calgary to Manchester in May at the time. Interestingly, I was a lot more worried about the flight being potentially cancelled due to snow in Calgary (actually not terribly unusual in May due to the altitude and proximity to the Rockies) than the ash from Lady E.

    *to/from the US

  19. In Stockholm we got a very very very fine dusting of ash
    I think parents cars got a superfine thin almost invisible dust layer when you scraped a finger on it
    thats the very finest ash that rained down on the Sweden craton

    • In south east UK I was most bemused to have to wash a layer of volcanic ash off my car before going to work. It was not much anyway – like yours, a very fine layer but enough to want to wash it off before it scratched everything.

      Rain filled with Sahara Desert sand can be fairly common here. Volcanic ash, in England? That was a new one! I never in my life thought I’d have to clean volcanic ash off my car here in the UK.

  20. The only volcanic effects I have seen are the sunsets after 2011 puyehue-cordon caulle, and I was not actually interested in volcanoes back then so I didn’t really take much notice… ;(

    • Holy crap…. I see anything from 0,4 to 0,8 km3 for Grimsvötn every year from many papers
      yes thats one of the highest magma infusion of any volcano on earth!

  21. There have been a few earthquakes in close vicinity of Hekla today. Mostly shallow ones (probably nothing serious) but it seems that we are seeing a clear uptick in activity in the past few months. I think an eruption in the not-so-distant future is still a good bet. The sensitive sensor equipment was a good investment, I think.

    Also note the earthquakes close to Grimsvötn today. The cumulative seismicity plot also shows a notable jump for the first time (in contrast to the rather flat line of the past 6-12 months). Perhaps this could be an early indication that Grimsvötn has reached a state where slowly pressure is building up.

    The was held for approval by the system for unknown reason. Hereby approved and future comments should appear without delay – baby dragon

  22. Mount Erebus is a volcano I wants to visit..
    Thats the only volcano in the world .. that haves a high viscosity lava lake about 100 times stiffer than Hawaiis lavas. That alkaline evolved phonolite lava lake is the strangest stuff I can ever imagine in my head.
    That lava lake behaves completely diffrent from the more fluid basalt lakes.
    Erebus is proof that even more viscous magmas can have lava lakes under correct conditions.
    Petrologicaly that volcano is intresting too.. with similar compostions as Kilimanjaro.
    Erebus is anorthoclase tephritic phonolite and phonolite with huge crystals
    Erebus magma rocks seems sometimes to have green light grey tone .. or even dark green – grey.
    Alkaline Continetal Rift volcanoes in the west antartic rift system.

    Visiting Erebus rim coud be dangerous as that stiff lava lake sometimes explodes with gas slug slow.
    I seen enromous phonolite spatter bombs thrown on the rim in old photographs etc… scary
    Despite being souch a cold cruel place, I wants to visit Erebus

  23. Grímsvötn is preparing to serve us some ash. This is starting to look more like the final sprint.

    07.11.2018 04:27:48 64.403 -17.288 0.4 km 2.6 99.0 0.7 km WSW of Grímsfjall
    07.11.2018 04:26:14 64.395 -17.290 1.9 km 2.0 99.0 1.3 km SW of Grímsfjall
    07.11.2018 01:53:05 64.382 -17.278 1.1 km 1.1 77.0 2.5 km S of Grímsfjall

    • More a marathon than a sprint, I think. If it follows the green line, we are still 1.5-2 years from eruption. If blue, more than 3 years. Dirk has it right, I think. Pressure is increasing and it is building up, but too early to call an election eruption. (That was predictive typing..)

      • In geological terms it’s definitely a sprint 😉

        I think it’s probably around a year left before anything happens. But it’s getting closer for sure.

    • I’m taking more interest in the few deeps quakes under Katla. And an interesting tiny cluster near Hekla. And I saw a couple of deep quakes under Bárðarbunga a couple of days ago. Deep, that’s where to look for ‘generally interesting’ stuff.

      • Yes, the deep ones under Katla are very interesting. Quite large magnitude for that depth. The area around Hekla is always interesting, since Hekla is usually so notoriously silent until the very last moment. The area SE of Bárðarbunga has had those deep quakes regularly for a long time and don’t really signal a change in activity.

        The reason I think Grímsvötn is interesting is that it has been very slow since the last eruption with almost a complete lack of M2+ quakes. Now, both the size and frequency of quakes is picking up.

    • The magma supply to Grimsvötn is very large, that volcano have never been dormant for more than few decades I think.
      As birdman says.. it have the potential to do very scary stuff.
      The most scary stuff happens when there is a major rifting event combined with sourge from the Mantle Plume
      Its then.. when you gets events like Laki, Eldgja etc
      2011 was a fresh sourge from the hotspot all fresh basalt and extremely gas rich.
      According to Carl there is around 500km3 of molten basalt inside Grimsvötns deeper parts

      • Parts of the dead zone havent rifted in a long time, in particular the bit extending from thordarhyna. Thordarhyna is on the grimsvotn swarm and very likely was charged with magma too, and probably has just the same capacity as grimsvotn although it doesnt erupt as often. Not to be doom and gloom but this is exactly the sort of thing that would send people into panic if it was a more notorious volcano.

  24. whooohoo! I simply cannot wait… until Grimsfjall erupts again
    These quakes are in the eastern parts of the caldera
    Fire inside the ice
    The next Grimsvötn eruption will likley be same size as 2004

  25. Im curious how large the next one will be
    Thats the yearly magma supply in grimsvötn in cubic meters?

    • Carl a few years ago worked out that the supply rate to grimsvotn is something like 0.2-0.5 km3 per year. This is most probably the highest value of any volcano on earth, and definitely in the top 3 along with kilauea and the klyuchevskaya group in Kamchatka. However because grimsvotn is on a rift it doesn’t erupt most of this magma, maybe only less than 10% of it, which is probably the reason why it isn’t nearly continuously active like kilauea. Still in theory there could be a pretty impressive eruption even now, 2004 was by no means small, if it was an effusive eruption it would probably be equivalent to mauna loas 1984 eruption, or kilaueas recent eruption before fissure 8 opened. 2011 was just absolutely massive, like a flood basalt that stopped half way.

      It will be very interesting to see grimsvotn later this century when probably a large part of it will be ice free, it’s eruptions will probably be a lot more effusive unless it has another massive blast like 2011, or a rifting fissure. Grimsvotn might become a very scary volcano if it becomes subaerial, it would be like a more localised version of the early Holocene magma surge except it is directly centered on the hotspot and that would also be combining with the latter stages of the current hotspot surge…

      • How can Iceland without a ridge… be Hawaii on steroids? as you told before
        Icelands hotspot.. is not as hot.. or deep or large as Hawaiis one.

        MY op= Iceland without the ridge… is an island group similar in size of the Galapagos

        • Ive seen some other stuff about iceland being bigger than I thought but I cant remember where I read that. However it is definitely bigger than almost any other hotspot

      • Still you are right… Iceland is a very powerful hotspot.. but its nothing like Hawaii

  26. RE: Hekla. Fedgar station (north-west of Hekla) this morning showed a small but interesting ‘slow quake’ that may have been magma on the move. Fires up at 09:27 and lasts three minutes before fading away. Hmmm….

  27. Looks like time matches these two

    07.11.2018 09:28:15 63.616 -19.093 21.3 km 1.7 99.0 4.0 km N of Hábunga
    07.11.2018 09:28:10 63.632 -19.039 16.0 km 1.9 99.0 6.5 km NNE of Hábunga

  28. Grimsvötn is likley a trapdoor caldera when it comes to eruption mecanism
    Just like Sierra Negra. Magma accumulate in grimsvötns upper magma chamber, thats a flat massive sill laccolith form thats feed by an open conduit. As the magma chamber expands.. it expands and cracks the sorrounding rocks causing earthquakes. It also inflates the caldera
    When the pressure gets high enough .. the magma goes through the ring faults in sourthen caldera and erupts. 1998 , 2004 and 2011 occured very close to eachother, maybe a more permanent eruptive ventile is forming there.j

  29. But if it is like that… there should be lots of earthquakes around the faults in the caldera floor slab over the expanding magma chamber in Grimsvötn. Thats what we are not seeing before a grimsvötn eruption.
    Grimsvötns magma system is quite poory mapped I think.

  30. Hmmm, first a couple of deep quakes under Katla with a somewhat strange associated waveform on the drumplots. Then, a while later, three small quakes on the Eldgjá fissure. Do you guys think they are related?

    • That’s what we’ve been wondering… Carl’s hopefully going to get something out on the recent activity tonight.

      On another note Tomas, I might contact you on a little coding project if you’re interested? I know you keep a DB of quake data for your bardy ring-fault quakes. I’ve been looking at some HTML/JS solutions for not only historic but real-time 3D plots for every volcano in Iceland. I’ve only played around with a small sample, but early results look promising just using CSV IMO data. I’ve not had much time to dedicate to this, and I’ve barely slept in weeks, so once my kids allow me some rest and I’ve learnt some new songs for the band I’ll PM you on FB for further discussions on it.

      • Sounds like fun. CSV IMO data is exactly what I use for my plotting. I don’t have any kids, but I do have a small farm and a bunch of horses, so finding time to dedicate to other fun stuff can be a bit difficult.

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