Pluto: the big-hearted dwarf + Katla Reawakening

A New Horizons image of Pluto showing its big heart

A New Horizons image of Pluto showing its big heart

Its career as a planet last for less than half its year. Pluto was discovered late, in 1930, as our final planet, completing the Sun’s brood of nine. (In hindsight it had been seen, but not recognized, as early as 1909.) But it was always an odd one, the runt of the litter, banished to the far flung regions of the Solar System. By 2006 the International Astronomical Union had seen enough. It instigated a new class of objects, intermediate between planets and asteroids (or minor planets), and re-assigned Pluto to be the primary member of this class, called dwarf planets. There were good reasons to do so: Pluto was just too small, on too strange an orbit, and worst of all, similar objects were being discovered. If Pluto was a planet, perhaps as many as 50 other objects out there could claim planethood too. NASA astronomers objected vehemently. NASA had just launched a mission to Pluto, called New Horizons. US Congress would not be well pleased if its money, awarded to investigate the last unexplored planet of the Solar System, would end up at a dwarf planet instead. The objections were overruled by a convincing vote. 76 years after being discovered and named, having travelled only a third of its 248-years orbit around the Sun, Pluto’s brief summer as a planet came to an end.

Still, this newly-named dwarf planet, frozen beyond belief, is a fascinating object. It has everything: weather, enormous climate change, active geology and volcanoes, a large heart on its surface, a family of satellites, and a mysterious past. Maybe being a dwarf planet should be a badge of honour, worthy of every penny spent by NASA.

An interesting aside, the name Pluto was first suggested by Venetia Burney, 11 years old at the time and living in Oxford. Of course we don’t know who named the original planets but perhaps this was also the work of children. Children have curiosity and want to push their horizons. Space was made for them.

This post will present our knowledge of Pluto, and its place in the Solar System, prior to the New Horizons encounter. Other (later) posts will be about New Horizons itself, and what we learned from the fly-by.

Children of the Sun



Two decades ago, when everything was simpler, the Solar System had only two types of planets: the rocky or terrestrial planets (Mercury, Venus, Earth and Mars) and the gas giants (Jupiter, Saturn, Uranus, Neptune). Pluto as a solid body was classed with the rocky planets.

The four rocky planets all have iron cores, underneath a silicate mantle. They have only small amounts of the so-called volatiles: water, methane, CO2. There is a reason for this deficit. The planets formed from solid particles which came together. Each mineral has a temperature below which it can be a solid (there is no liquid phase in vacuum). For iron and silicates, this condensation happens at when temperatures drop below a balmy 800-1000 Kelvin, but water, methane and CO2 freeze out only below a chilly 200 K. The rocky planets formed at a distance from the young Sun where the temperatures were in the range 300 to 600 Kelvin. So water, and other volatiles, were in a gas phase and absent from the solid particles which made up these planets.

The 200-K temperature was reached somewhere within the asteroid belt. This is called the snow line. Further out, water became solid. Any ‘rocky’ planets forming out here would contain major amounts of water. In reality, the boundary wasn’t as sharp as the name ‘snow line’ implies, and the fraction of water in planets slowly increases further out, being very low for Earth, larger for Mars, and larger still for many asteroids.

The four gas giants are nowadays divided into two groups. Jupiter and Saturn, the monsters of the Solar System, are true gas giants. Uranus and Neptune, rather smaller but still 15 times heavier than the Earth, are considered water giants. They contain huge oceans in their mantles, above a rocky, Earth-like core.

The moons of the large gas giants, being outside the snow line, also are a mixture of rock and ice, with more ice than found in a typical asteroid. In all these objects, ‘ice’ is mainly water ice but it also contains ammonia, CO2, and methane.



How does Pluto compared to the rest of the family? If you like your information in numerical form, a Pluto factsheet is maintained by NASA. But the facts need interpreting.

Pluto’s mass may seem impressive, but it is positively minute compared to the planets: it is a midget, only 0.2% of the Earth, and 20 times less than the smallest planet, Mercury. Embarrassingly, seven moons in the Solar System are larger than Pluto. The orbit is also strange for a planet, very elliptical, with the distance to the Sun varying by 50%. For comparison, for Earth it varies only by 3.5%, and for Mars (the most elliptical orbit among the planets) the variation is 18%. Pluto is in a different league. The orbit is also well outside the plane of the ecliptic where all other planets are found. It really is an outcast.

Pluto is just about large enough that during formation, the interior would have melted from the heat of the colliding fragments. The melting will have allowed the denser silicates to sink down, and Pluto is thus expected to have a rocky core, surrounded by a water mantle. There is also an atmosphere, mainly consisting of nitrogen, with a pressure of 10 microbar, comparable to the Earth’s atmosphere 100 kilometer above the surface. Temperatures at Pluto are around 40 Kelvin, or -243 C. (If you live in one of the seven countries following the Polish-born Daniel Fahrenheit, this is -387 F.)

The internal structure of Pluto. Source: wikipedia

The internal structure of Pluto. Source: wikipedia

Pluto’s giant moon is called Charon. ‘Giant’ is relative, but Charon is large enough that some consider it a dwarf planet in its own right. Whereas Pluto has a diameter of 2370 km, Charon is 1200 km across. (For comparison, our Moon is 3475 kilometer across.) Four more moons were discovered in recent years. They are very much smaller, and a bit further from Pluto than Charon. Interestingly, the orbits are in resonance: the orbital periods scale approximately as 1:3:4:5:6, which is the only way such closely spaced moons can stay in stable orbits. The four large moons of Jupiter have the same kind of resonance.

Charon takes 6.4 days to orbit Pluto (that is the ‘1’ in the 1:3:4.. sequence above). Pluto’s own rotation period is also 6.4 days, as is Charon’s day. In other words, they are tidally locked, both always showing the same face to each other, just like our Moon does to us (but the Earth does not to the Moon).

Making Pluto

How did this complex system form? It seems unlikely that a dwarf planet so far out in the Solar System can pick up 5 satellites! There are too few free objects around there for such multi-dating. The circular orbits of the moons suggest that they formed in situ, around Pluto, and were not captured from abroad. The large size of Charon is most easily explained as caused by a major impact during the formation of Pluto, which effectively split proto-Pluto in two. This impact would have been even more devastating (relatively speaking) than the one that formed our Moon. The other moons could have formed from debris from this impact. But could such a major impact have happened in such an empty region of the Solar System? Isn’t it a bit like a world-class collision in a road-less region in the desert heart of Australia, traversed by one vehicle per month?

A clue comes from the densities of Pluto and Charon. These are around 1800 kg/m3, midway between ice and rock, meaning that both are very roughly equal parts ice and rock. This is very similar to Titan and Enceladus, moons of Saturn. The moons of Jupiter, in contrast, are denser and have more rock than ice. Remember that the further from the Sun a planet or moon formed, the higher fraction of ice it contains (Earth has essentially none). Pluto will thus have formed somewhere in the general region of Saturn, which is much closer to the Sun than it is now. During a chaotic phase in the early Solar System, a lot of smaller bodies were thrown out of this region by encounters with Saturn and Neptune. It explains the strange orbit of Pluto. The collision that formed Charon could also have happened during this period of chaos.

Surface features

Long before New Horizons was launched, we knew that Pluto has an interesting surface. Its brightness changed, such that the dwarf was considerably brighter when the side facing Charon was pointed towards us. There was a more reflective material on that side, and the most likely culprit was ice; nitrogen ice, to be precise, which is white at very low temperature, around 40 K. (When ‘warmed’ to 60 K, it becomes transparent, and at 63 K it evaporates.)

The Hubble Space Telescope had a go at mapping tiny Pluto. It found a particular bright region, neighbouring a very dark area. The dwarf planet also appeared to be changing: over a decade, the northern (darker) hemisphere was brightening, and the southern hemisphere fading. Over this time, the density of the puny atmosphere had doubled. Pluto was showing seasons!

We now know that the bright region is the same as the ‘heart’ found by New Horizons. Discoveries often have history.

Seasons of the heart

Pluto’s seasons are funny. Of course, this far from the Sun’s warmth, the seasons change between winter and ice age; you would not expect to find anything resembling summer!

On Earth the seasons are determined purely by the tilt of the polar axis. The angle between the orbit around the Sun and the Earth’s rotation is 23 degrees: this tilt causes the varying length of day, and the varying height of the Sun above the horizon. Within 23 degrees of the equator, the Sun can get to the zenith: these are the tropics. Within 23 degrees of the pole, there are times when the Sun doesn’t set or doesn’t rise, depending on the season: these are the polar regions.

Pluto’s inclination is more than double that of Earth, at 57 degrees. This makes the seasons much more extreme. (The tilt is actually 123 degrees: the planet rotates upside-down and the Sun rises in the West. But the effect is the same as a tilt of 57 degrees.) As the dwarf moves around the Sun, at a certain point in its 248-year orbit the Sun will be above the equator: this is the equinox when day and night are the same length, everywhere on Pluto. A quarter orbit along, the Sun is only 33 degrees from the north pole of Pluto: the southern quarter of the planet is now in perpetual darkness and the northern quarter in perpetual sunlight. Than the Sun moves back to the equator, and finally to close to the south pole, and the polar day and night are reversed.

On Pluto, the ‘tropics’ (this name could be seen as optimistic) and the polar regions overlap: there is a region at intermediate latitudes where during the summer the Sun gets to zenith, therefore it counts as the tropics, but this Sun never sets, and half an orbit later the same region has a perpetual polar night; so it is both tropical and polar. At the moment, the Sun is not far from the equator and all of Pluto gets some sunlight. Spring has begun in the North, and the South is heading towards its century-long winter night. Pluto’s climate was designed for Sleeping Beauty.

Pluto's year. Source:

Pluto’s year. Source:

A second problem is that the distance to the Sun changes so much during the Pluto year. Closest approach occurs during the spring equinox in the North (or autumn equinox in the South). The northern summer and southern winter happen when Pluto is far from the Sun. The South therefore has more extreme temperatures – a colder winter and warmer summer. The South has climate and the North has weather. Also, note that Pluto moves much slower when further from the Sun, so that the seasons are of very unequal length.

With Pluto just coming out of the northern winter, the expectation was that at the moment there is a nitrogen ice cap in the north, in the process of evaporating, while the southern ice cap has not yet started to reform. The atmosphere is therefore denser than usual. As Pluto moves away from the Sun, much of it will condense as frost and ice, on the southern hemisphere. The ice cap resembles an anti-swallow, migrating from winter to winter.

Is there life on Pluto?


Pluto’s siblings

There are four groups of objects in the outer Solar System similar to Pluto, ranging from puny to Pluto-sized. Over a thousand objects are known, several of which are large enough to be dwarf planets. Together they are called the Kuiper belt.

The first, and largest, group contains the ‘classical objects’: they have mildly elliptical orbits, around 42 to 45 AU (1 AU is the distance Earth-Sun; Pluto is at 39 AU), and most are close to the plane of the ecliptic where the planets are found.

The Kuiper belt. Source:

The Kuiper belt. Source:

The second group have the same orbital period as Pluto but very elliptical orbits (each one different) and a variety of inclinations to the plane of the ecliptic. These are called the plutinos. Their orbits are in a 2:3 resonance to Neptune, meaning that for every three orbits of Neptune, they do exactly 2. Many cross the orbit of Neptune (as does Pluto), but because of this resonance they never come close or collide. There probably used to be more, but any that had different orbital periods were slowly removed by Neptune. Gravity is a bastard: it can be slow and weak, but it always wins.

The third group is the ‘scattered disk’: these objects are much further out and their orbits are highly elliptical. The dwarf planet Eris, almost as big as Pluto, is a member of this group. They have clearly been thrown out here after coming too close to one of the giant planets, probably Jupiter, and coming off worst. Now they are the cricket/baseball out-fielders: hanging around, not doing much, waiting to catch the odd ball coming their way.


The largest Kuiper belt objects. Source: wikipedia

The largest Kuiper belt objects. Source: wikipedia

Finally, a few of the moons of the giant planets are similar to Pluto, including Phoebe (orbiting Saturn) and Triton (orbiting Neptune).

Triton is in some ways the other Pluto. It orbits Neptune in the opposite direction to Neptune’s rotation. That indicates it hasn’t always been there but was captured by Neptune at some time. Triton is a bit larger than Pluto and has a little bit higher density: a bit more rock and a bit less ice; thus, it probably formed closer to the Sun, perhaps near Jupiter. Like Pluto, Triton has a nitrogen atmosphere. Triton was photographed during the Voyager encounter, in 1989. It showed a surface that is a mixture of dirt and nitrogen ice: the lack of impact craters suggests that the ice is quite young (or re-formed regularly).

The surface of Triton, as photographed by Voyager

The surface of Triton, as photographed by Voyager

Most excitingly, Voyagers found geysers on the surface, ejecting gas kilometers high. These were only seen where the sun was directly above Triton, in the zenith. The geysers are probably from nitrogen: phreatic nitrogen volcanoes. Nitro-thermal activity, if you prefer.


The geysers of Triton raise the question how common volcanoes are, out there in Tevya’s frozen wastelands (from Sholem Aleichem’s Fiddler).

All rocky planets have volcanoes (remember Venus). These planets produce liquid rock, which rises to the surface as lava, either effusively or explosively. But the outer Solar System has less rock, and more ice. Would you expect volcanoes? And to melt the magma, a heat source is needed. Does that even exist in these small, cold bodies?

Io, the hellish moon of Jupiter, is a clear case in favour. It is the most volcanic surface in the Solar System; the heat is supplied by huge tides (on solid rock!) from its boss, Jupiter. Nearby, the asteroid Vesta once had a magma ocean, albeit only when it was young. But both of these bodies formed close to the snow line, and still are largely rock. Further out, where ice rules, volcanoes are very different.

Here, on the ice worlds, you would expect that volcanoes erupt liquid water rather than liquid rock. Many of the moons are now believed to have water oceans deep underneath the surface, and these take up the role of a ‘water magma’. But water is not a good volcanic substance. When rock melts, it becomes less dense and the magma therefore rises up towards the surface. When ice melts, its density increases and the resulting liquid tries to sink. You know this from experience: ice floats but rocks sink. Down is the wrong direction for volcanic eruptions.

Turning water into a gas does give the required upward pressure, perhaps even too much of it. This gasification can happen close to the surface and results in a Yellowstone: huge geysers erupting into the sky. (Under near-vacuum, liquid water does not exist and all eruptions become gaseous when reaching the surface.) The result is seen on Enceladus: geysers erupting from a sub-surface ocean, going so high that some water escapes altogether and ends up on other moons. The geysers of Enceladus are one of Brian’s wonders of the Solar System. Would you call this a volcano? When it goes this high, you might as well. (But to play the devil’s advocate, comets work the same way and would you call the jets that form their tails volcanic?)

Even further out in the Solar System, the surfaces are mainly nitrogen ice. When this is transparent, sunlight can penetrate and heat the material underneath. This is probably what powers the geysers of Triton. At 40K, nitrogen ice is white rather than transparent and this underground heating does not work. So one might expect that Pluto would not have such geysers.

The ninth planet

Let’s come back to the plutinos. A paper published in early 2016 pointed out that their orbits were remarkably similar, with the closest approach to the Sun occurring in the same area of space. This was a strange alignment which could not have happened by accident.


Models show that only the gravitational pull of another body could do this. This body would be perhaps 200 to 1000 times further from the Sun than we are, on an elliptical orbit with a period as long as 10,000 year, and could be as massive as Uranus or Neptune, large enough that there should be no doubt about its classification as a planet. The models appear quite convincing. We haven’t found it yet and it will be very faint. But it does appear that the Solar System again has nine planets, not eight, and the final member which occupies the vacancy left by demoted Pluto is our third water giant. It cannot have formed as far out as it appears to be now: most likely it formed close to Saturn, and was ejected during an ill-advised close approach, in the years of chaos in the young Solar System. Now it lives in the Solar System’s Siberia, far from civilization but still out there after all these years. A true wanderer.

If we only knew where it was, New Horizons could perhaps be redirected at it. It might take a century to get there, but the US Congress’ money would still be used for its original purpose: visiting the final planet of the Solar System.

New Horizons

So we knew a fair amount about Pluto. And finally a spacecraft came to have a look. New Horizons was launched in 2006, still in the years of Pluto’s planethood, and traveled for nine years, with a quick fly-by of Jupiter on the way to pick some extra speed. On 4 July 2015 it reached Pluto. Unable to carry enough fuel to stop, it flew past within hours. These hours transformed our knowledge. The dwarf planet became the world with the big heart.

To be continued



Katla Reawakening?

View over Katla photographed by Dagur Bragason today. Used by kind permission by the photographer.

View over Katla photographed by Dagur Bragason today. Used by kind permission by the photographer.

Over the years I have written very little about Katla. The reason for this is that Katla has done very little to merit an article. Here at Volcanocafé we have written a few posts about Katla, but all have been attempts to put facts up against all the alarmist trash that has been written over the years.

This has though changed lately, but before we start talking about resent activity we need to look a bit at Katla to have our facts straight. In other words, we need a historic background to judge what is happening against previous eruptions. Below I will only write about eruptions that are known to really have happened and I am not included mini-eruptions or eruptions only to be found in the heads of people with feverish minds.

Background of Katla

Historic size and distribution diagram by Icelandic Met Office. Note that M3.4 was the largest recorded earthquake up to last week.

Historic size and distribution diagram by Icelandic Met Office. Note that M3.4 was the largest recorded earthquake up to last week.

Katla is the third largest volcano in Iceland with Bárdarbunga and Grímsvötn being slightly larger. All 3 of them come with slightly different “flavours”. Bárdarbunga is more into large effusive eruptions and small explosive eruptions. Grimsvötn is all over the map producing explosive eruptions ranging from VEI-2 to VEI-6 and has had 3 known large effusive rifting fissure eruptions.

And a plot showing todays hubbub. Notice that the twin M4.5 expended 1.5 times as much energy than all recorded Katla earthquakes in one go. Image by Icelandic Met Office.

And a plot showing todays hubbub. Notice that the twin M4.5 expended 1.5 times as much energy than all recorded Katla earthquakes in one go. Image by Icelandic Met Office.

Katla is more consistent with predominantly large explosive eruptions from the caldera and one prolonged large effusive eruption. Katla has had 30 eruptions since 820 giving an average of 40 years between eruptions. That average is though just a statistical number that obviously can differ a lot.

The longest repose time during that time was 100 years and the shortest well dated repose time is 12 years.

In regards of how explosive the eruptions has been we get a pretty good picture from the records. I am here only using those eruptions that has a classification in the Global Volcanism Program from 820 and onwards. 3 eruptions had a Volcanic Explosivity Index (VEI) of 3, 14 eruptions had a VEI of 4 and 4 eruptions had a VEI of 5.

The average size of the eruptions is why Katla has such a fearsome reputation, especially since it is located unusually close to settlements. After all, the volcano has an average size of eruptions that ranges somewhere between a medium sized VEI-4 to a borderline VEI-5.

During eruptions between 0.05 to 5 cubic kilometers of ash is released and here the bad news is that the ash is very fine grained and needle like, so the effects on air traffic during an eruption could be significant depending on the weather pattern during onset of eruption.

The greatest threat to the locals is the well known very large jökulhlaups that will come pouring out of the caldera during an eruption. These jökulhlaups are so large that they can remove entire farms, take out a long stretch of the national highway and usually changes the entire landscape. During the last eruption the jökulhlaup transformed the entire coastline below Myrdalsjökull and the ash, mud and stones deposited added several square kilometers to the surface of Iceland.

The extreme oddball of the eruptions is the Éldgja fissure eruption that started in 934 and lasted into 940 and deposited 18 cubic kilometers of fresh lava.

Current activity

Alftagrof station, image by Icelandic Met Office.

Alftagrof station, image by Icelandic Met Office.

In 2013 the earthquake pattern of Katla changed and recurrent brief episodes of small deep earthquakes started. Those earthquakes range between 20 and 30km+ depth and are a sign of magma moving upwards into the system of the volcano. During early 2016 the size and frequency of these earthquakes increased indicating an increased rate of magma influx from depth.

During all of the years that we have had instrumented recordings of earthquake sizes in Iceland Katla has suffered a few M3+ earthquakes with the record being at M3.4. So it was a bit of a surprise last week when Katla banged off an earthquake that was M3.5. It was shallow and the signature indicated that it was related to hydrothermal activity caused by fluid movement.

And here we come to today’s earthquakes. During the night leading to today there was a brief and intriguing earthquake swarm in the northern part of the caldera. A spot that Henrik Lovén already in 2011 pointed towards being both the most likely spot for an eruption, and as being the most likely for a slightly larger eruption in a series of articles he published here debunking that Katla would erupt soon (it was during the Katla scare following Eyjafjallajökull).

So, what makes this brief earthquake swarm so interesting? First of all we have to take into account the size. After all we had a new record earthquake size last week, and now we had 2 earthquakes within 20 seconds apart measuring M4.5. And as everyone knows the destructive force is 27 times larger in an M4.5 earthquake compared to an M3.5 earthquake. So, the record was not only broken, it was shattered completely.

Another way to look at it would be like this, within a minute Katla released more seismic energy than has been recorded by instrument for that volcano. Yes, those two earthquakes released more energy than all of the ten thousand plus recorded earthquakes at Katla, something to ponder indeed.

Another thing is that during the hour prior to the two large earthquakes we have several episodes that can be interpreted as fluid movement and one episode after. This would indicate that fluid started to move, putting pressure on the magma reservoir causing two large tectonic type earthquakes that in turn created a void that more fluid moved into.

The depth of the events makes it highly unclear if it was magma or hydrothermal fluid (super hot water) that was on the move. After the event the earthquake swarm has continued with smaller earthquakes with the largest as I write being M3.3.

Volcano forecast

Slysaalda station, image by Icelandic Met Office.

Slysaalda station, image by Icelandic Met Office.

Last week I wrote an article about Grimsvötn where I described my favorite method of modeling the likelihood of an upcoming eruption, the finite element threshold analysis modeling method. It basically is a way to try to calculate how much pressure increase a volcano can take before it ruptures like an old boiler tank.

And like an old boiler tank a volcano will creak and groan as it closes in on an explosion and that the amount of creaks and groans will increase exponentially as the volcano closes in on an eruption. For Katla we do not know how much of the creaks and groans there will be prior to an eruption being inevitable.

I will here return to the known increase of magma influx from depth and the very sudden increase in energy released as earthquakes at Katla. In my view a volcano that suddenly changes its pattern is about to do so in more ways than just as being more seismically active. In my way of modeling this is exactly the kind of sign a volcano would give as it comes close to the breaking point that the model predicts.

I am certain that the volcano has reached the tipping point of no return. If things calm down now it will still be closer to an eruption and if it continues or intensifies it is only a question of a relatively short time before we get the steady thrumming earthquake swarm that we know from other Icelandic eruption run ups. Right now I would say that we are days to years away from an eruption, but if the activity continues or intensifies I would say we are days to weeks away. The change in behavior is after all that significant.

In 2011 Henrik Lovén wrote this; “While a larger “proper” eruption of Katla in the VEI 3 – 5 range cannot be ruled out, I find one unlikely at present as the current activity mostly is in areas already depleted of evolved magmas by geologically speaking very recent major eruptions. Also there is little sign of the uplift required on GPS. If one were to occur, the odds for one towards the upper end of what Katla is able of ought to be better in the Eastern to Northern parts of the caldera.”

This also follows the modeling prediction that the greatest likelihood of an eruption occurring in a part that has not recently erupted since the pressure there should be larger, a pattern that is known for the Icelandic caldera volcanoes.

In short, if I use my own model of prediction (and I should) it seems to say that Katla is nearing an eruption. Due to lack of data prior to an eruption I can’t calculate when exactly it will occur, but if the current swarm continues over an extended period or suddenly intensifies and continues we should see an eruption in the not too distant future.

For those interested in a more in depth explanation of the finite element threshold method I recommend my previous article about Grimsvötn.



308 thoughts on “Pluto: the big-hearted dwarf + Katla Reawakening

  1. Info from IMO tonight:

    Glacial water is flowing into Múlakvísl river, south of Mýrdalsjökull. Increased conductivity has been measured in the river and gas measurements in the area show high concentrations of sulfur dioxide and hydrogen sulfide. People are advised not to travel near the river, due to gas pollution. It is not uncommon for glacial water to flow into Múlakvísl, causing increased conductivity and gas pollution.

    According to local reports, the level of the Bláfjallakvísl glacial river is unusually high. Bláfjallakvísl originates from the northern side of Mýrdalsjökull and people are advised to show caution when crossing the river.
    Written by a specialist at 29 Aug 19:33 GMT

  2. I’ve been gone for 1 day! Perhaps Katla said you want to talk about outer space I’ll show you some stars.
    Liked your the article, Albert. It has a couple of my favorite topics. 🙂 Now to read the addition about Katla.

  3. Can anyone tell me from this picture, where is the north? Where should we look exactly? Where is the “fragile” spot?

      • Ding!

        Bjarki is not being facetious. Katla IS that big. You are looking at pretty much the whole caldera. Any point of which, could be the start of festivities.

        If my perception of the camera angle is correct (which is just as likely to be wrong) the area that Henrik was talking about is in the left third of the view… with north being over your left shoulder.

        • Salut Alzé! If I recall correctly, the webcam is located to the SSW of Katla (in the vicinity of Heidarvatn north of Vik-i-Myrdal) which would make the area where the largest earthquakes hit appear to the right of centre.

  4. Hm! My comments about the changes in groundwater as an indicator that there is increased geothermal activity beneath the icecap seem to ave been timely. This does not mean there is going to be an eruption but as ever we watch,wait and contemplate.

  5. Katla. Some wait for it since her little sister rumbled in 2010. Not that we didn’t have some entertainment with the MAR… But Katla is such a cool volcano. At least I think it’s cool. Yeah, actually all Icelandic volcanoes are super cool. Ha! Rumble under Katla and Carl in full prediction mode (or mood). Funny days ahead. And doom potential. Fabulous.

  6. Am I right in thinking that when the eruption is about to start we’ll get a swarm similar to the one at Bardarbunga that started on 16/8/14?

    • Yes and no.

      The Bardarbunga swarm was a bit different as there was a good sized dike that protruded, and cut all the way from the Bardarbunga caldera towards Holuhraun. Also, there was a lot of tectonic activity at the time (whether this caused, or was caused by the eruption is tough to say).

      Additionally, the gradual blocking of the caldera lid was extremely noisy, and since it occurred at a gradual rate, lasted for a long time (and it’s still occurring on occasion).

      Were an eruption to occur here, if there is a dike formation similar to Holuhraun, I could see it being quite noisy, but the more likely scenario is an explosive eruption. This will likely be pretty noisy for a short bit, but the lead from the onset of the activity to the time the actual eruption occurs will likely be a good bit quicker. After that occurs, seismicity will likely die down a good bit.

          • They need to be as first of all, the glacier to be punched through is between 300 and 700 metres thick, and second you inevitably get a lot of interaction between even the most basaltic of magmas and huge amounts of water (as KarenZ points out).
            “Phreatomagmatic BOOM”

    • Mjf! If my memory is not at fault, the 1918 eruption was preceded by tremors felt as far away as Reykjavik (M5+ ?) so yes, you would expect to see something similar. That is not to say that this will necessarily turn out to be so as no two volcanoes are exactly similar in behaviour.

      • My book just says a sharp quake followed two hours later by a jökulhlaups and the eruption column. No mention of any other tremors or of anything felt as far away as Reykjavik.

  7. Hi Guys it is good for you to be back, some intereating times are ahead. I got another moniker, it is ok the old one wouldn’t let me log in, Ursh

  8. Thank You Albert, I was reading about Pluto and really tried to learn or re-learn about something really fascinating when I realized I had missed some excitement:D

  9. red and green tremors are going up on 1/2 of

      • Henrik posted this in the Facebook group :

        It’s the IMO drum plot located at Alftagrof south of Myrdalsjökull and shows the increase in “tremor” caused by the “low” with winds up to 18 m/s passing immediately to the south. 🙂

        • Thanks Hobbes! In Mart’s case it’s the nearby Lagu Hvolar station (~16 km to the ENE of Alftagrof) but that and all stations on the south coast of Iceland show the same weather-related rise in tremor.

          Edit: I’d better add the IMO winds map to make it crystal clear / H

          • Good Morning Henrik . thank you for that info. saves lots of speculation. All is relatively quiet round Lady K. this morning. 🙂

          • Good morning Diana! That’s exactly why I put it up on FB where it would spread the quickest. Thanks should go to Tommy for putting it here as well.

  10. I really like this SIL staion. It shows a really nice “Normal” pattern the blue regular peaks are when the fishing boats return and leave in the mornings and evenings of a work day. And this is disrupted usually by incoming cyclonic weather as seen here by the rise of all three colored graphs. Also any major volcanic activity under the Myrdalsjokull Ice cap would be picked up. If I am wrong in these interpretations please let me know as these graphs are not easy to interpret.

    • I still remember the feeling when I first realised it was nowt but a reflection of human activities, regulated by working hours, and how you could “spy” on the generalised behaviour of human beings through a tremor graph. :mrgreen:

  11. Can someone here give me a link from the live webcam from katla? My link doesn, t work friendly greetings Dee

      • Don’t know. If it was just storm-related, there should be a rise on the blue line so that it is parallel with or above the red and green lines.

  12. Veðurstofa Íslands ‏@Vedurstofan 30s30 seconds ago Iceland
    Glacial water flowing in Múlakvísl river S of Mýrdalsjökull. Gas measurements show high concentrations of sulfur dioxide & hydrogen sulfide

    • Could you give us proles a quick and dirty rundown of how to read these? I know that the duration of each quake can be read on the bottom line, and obviously the larger quakes give of a larger signature, like that blue one.
      I guess what I’m asking is, is there any more “hidden” info in these plots?

      • Unless you’re a specialist, it is hard for us amateurs to do it with any degree of certainty as there are so many types and that regional earthquakes, that is quakes picked up at a great distance, tend to “smear” until they resemble other types, particularly hydrothermal or magmatic related tremor. The largest quake in Mike’s picture has a distinct tectonic profile whereas the lowest one (at appx 13:34-36) could be either a squashed teleseism of a distant earthquake or a local tremor/volcano-tectonic one. (In reality it is a teleseism, labelled as a “Regional Earthquake” in the chart below, of the Bardarbunga M3.8 at 13:33:28). Then you have instances of almost simultaneous quakes that blur or mask each others true profiles. For fun, you could try and identify some of the quakes from a comparison with the chart below.

        Ed: Since Mike posted a link to the page, the picture slowly changes and the big quake I spoke about is no longer visible. / H

        • Thanks Henrik. A very useful too for the amateur watcher. Can this image be saved somewhere for future use to save hunting through the comments please?

    • It is tempting to see it like that and it may be right. But the human has a tendency to pick up patterns that may not exist , but linking up the dots. (the canali on Mars come to mind). What you have is a linear pattern in the south, and two groups in the north which together give the impression of a curve. It is not yet a ring.

  13. Tuesday
    30.08.2016 13:33:28 64.674 -17.437 2.3 km 3.8 99.0 5.7 km NE of Bárðarbunga

  14. Whilst I wait for my Bread to rise…. just a quick query. Is the Dalek on Hekla still there? I lost many of my web cam links when I changed my computer and after the Hat eating comments my friend the Dalek came to mind. 😀

  15. And now that GeoLoco is back in his new disguise as WTF I recommend every newcommer to pester him for an educative lesson in Mudslides.
    Trust me, he is the master of mudslides (and all other assorted weird geologic thingies). Oh, and I am entirely bribable to send a certain picture of him to the ladies.

    • And also, now we know that Kynmökeldfjalliðsemenginnmákveða will erupt soon.

      • for the french speaking people could you claridy pls

        • It is my own invention in regards of the Icelandic faiblesse for naming volcanoes with highly “graphic” names. A very fancy way of saying “Mount Unpronouncable”

    • Yeah or paraseismic construction or quarry blasts or karst sinkholes or rockfall or the fight for maintaining the legendary work-life-balance… Better just ask me for bad jokes, and if you come to see that picture, wear sunglasses. My smile or my security vest might be a lot to bear for your eyes…
      As usually Carl is blowing up things. All geologists have universal knowledge, that’s not specific to me. And we are the coolest and sexiest men on the planet. But that’s a side effect of the universal knowledge.
      Now on the serious side of things, I tried to register as Loco, but didn’t get any feedback and can’t log in with my WP profile juste like that. That’s why I came in with my Twitter profile. Anything pending or shall I just try again?

    • You have to be careful of mudslides. Too many of them and the girls start dancing on the tables.

      • <<<<<<< shoves out the Picnic table and sunshade pole.

      • Hi Lurk.
        Reading you has always been delighting.
        Also in silent reader mode.
        And for sure you have understood the connection between slides and girls.

        • Yup. I am not fond of chocolate, or anything resembling a chocolate milkshake.


          1 – Part Kahlúa
          1 – Parts Absolut Vodka
          1.5 – parts Irish Cream Liqueur

          The general method I’ve seen used is to blend the whole shebang with ice until it is the consistency of a milkshake. CAUTION: This is one of those sugary drinks that make you fall down if you drink too many in one sitting. Back when I was allowed to drink, I preferred either beer or shots of Jim Beam. Much easier to keep track of how tanked you were before you attempt to move.

          Boilermakers? No thank you, that’s just plain nasty.

  16. Tuesday
    30.08.2016 16:48:48 65.036 -16.840 0.9 km 3.2 62.08 11.0 km W of Dreki

  17. Tuesday
    30.08.2016 16:56:33 64.668 -17.422 3.2 km 3.4 99.0 5.9 km ENE of Bárðarbunga

    • Thanks Bill. The first thing I do when I get online is to go here and see what the Bard’s up to. I like also how you can grab the graph and move it to look from different angles. 🙂

  18. Tripel green star now for Bardy today (Think Bardy and katla are having a sing song lol)

  19. So assuming the Askja quake is verified, we will soon have green stars in four distinct, separate regions at the same time in Iceland. Definitely a first for me.

    • That being said, looking at the drumplot of Askja, I have a feeling this is a ghost quake or error that will be scaled down.

    • Per definition both had tectonic signature, but the question is what caused the tectonic type earthquake to happen? Remember that Bardarbunga had only tectonic type earthquakes right up until he blew.

      • The prelude to the Eldgja eruption (Katla) in 934 with eruptive fissure of 60-70 km would most likely have included some tectonic movements.

        • Not that I am suggesting or predicting anything of that nature in the near future to make that clear.

  20. Hey 🙂
    I need to ask something :/ Hábunga and Gódabunga both are in myrdalsjøkul? Who is who? XD

    • Mýrdalsjökull is the name of the entire glacier on top and around Katla volcano (caldera).
      Háabunga is the name of a sub-glacial peak on the southern part of the Katla caldera.
      Goðabunga is the name of a sub-glacial peak on the west part of Mýrdalsjökull glacier – outside the Katla volcano caldera.

      • Here is a link to a writing about Mýrdalsjökull glacier monitoring which might be interesting to some readers of VC.
        On the overview page is a map of the glacier which roughly indicates where Háabunga is and other names of individual parts of the Mýrdalsjökull glacier.

  21. According to written sources by eye witnesses things happened pretty fast on the 12th of October 1918.

    An earthquake was felt in nearby town of Vik (not Reykjavik) between 13.00 and 13.30.

    Due to fog there was no view to the glacier. Around 13.00 local farmers that were about 15 km east of the glacier heard increasing sound of flowing water, which they at first thought was from a nearby waterfall but soon realized was a jökulhlaup from Katla (Kötluhlaup).

    The local farmers were gathering their sheep and had to make a run for their lives, riding their horses as fast as they could for quite some distances – some of them had a pretty narrow escape – the closes calls were about 40-50 meters.

    About 15.30 the Kötluhlaup was at Hjörleifshöfði (where the ring road lies).

    • Nice paper, thanks!

      For anyone interested, there are a couple of good photographs of what a subglacial eruption looks like. One of Gjálp, and another of Grímsvötn punching through 500 meters of ice.

    • Im travelling at moment but excited to see this. More deep quakes should be expected, then a m5 should suffice before katla starts to erupt.

      I think all could happen between a month or two but also perhaps longer like a year. Katla tends to erupt late Summer or autumn. Anyways we are really getting there but i expect the eruption this week yet!

    • Why is it so amusing to me? It fits the general nature of mankind. Many years ago, a room-mate of mine in service school down at Corry Station, fell out of a tree and broke his arm when base security interrupted an amorous adventure he and his friend were having in a pine tree right about here: 30°24’13.44″N – 87°17’42.80″W (give or take. It’s the same stand of trees, but I don’t know which one)

      • Good evening Lurking. Many thanks for the link. I now know why my fall was such a pain in the ar….rear end….It wasn’t a fall it was a “vertical deceleration event” . This explains everything scientifically and makes me feel less of doddering old fool 😀 Hope the dogs and Mrs L are fit, well and annoying you to the full 🙂

        • Amongst us oldies, I had a rapid “vertical deceleration event” when my face decelerated into rocks on St. Justinian’s beach in Wales just last week. My daughter told me: what did I expect would happen if I went climbing around a beach at my age – I should have known better. Now that’s a turn about for the books when my daughter ticks me off for hurting myself pottering around a rocky beach. Lucy’s genes are alive and well in my body, it seems.

          Good thing I was not wearing my specs at the time, too.

    • Lucy may have fallen out of the tree, but now we have ambulatory CD players…

    • Lucy was probably not our direct ancestor but our common ancestor was maybe even more of a tree climber. And, I at 60+ and my grand kids still enjoy climbing trees and rocks. Stultus genes were probably there from the beginning making us taking the risk.

    • Other than being on opposite ends of an aseismic area we call “the dead zone,” no. Overall tectonic stresses are about the only thing they have in common. They both are partially built on top of the Eurasian plate. Bardarbunga has the added treat of being on a triple junction… and almost directly over the Icelandic hotspot.

  22. Don’t know about current activity but in 934AD the Eldja fissures went from Myrdalsjökull to Vatnajökull. The 1783 Laki fissures only made it about halfway across on the Vatnajökull side.

  23. I know Icelands volcanoes are in a leaqgue of their own, but this is……

    • Thank you. Calmingly beautiful. 🙂 Iceland does things well.

    • If you ever talk to a volcanologist – never use the words “due” or “overdue”. They say that volcanoes can show periodic eruptions, but it is unknown why this happens and what changes this. So it may be that Hekla showed this between 1970 and 2000 for some reason, but it didn’t show it before and we may be back to that. Same is true for Katla, only because it has erupted approximately every 50 years, it doesn’t mean that this will happen forever.

    • No, not really as the 1947 eruption signaled a change in the behaviour of the volcano towards much more frequent eruptions. We have no way of knowing if Hekla is still in the same mode of more frequent eruptions or if a shift back towards longer intervals has already ocurred.

      There is also the greater picture to consider that before eruptions began at Hekla about 7-8000 yBP, they happened at Vatnafjöll which has been silent since. Possibly with the event of more and better instrumentation, it seems that activity at Vatnafjöll may be beginning anew.

    • Hekla has indeed changed pattern, not only once, it has done so twice and will probably do it again as it continues to evolve. It is after all a very young volcano (7800 years old).
      It used to erupt seldom but large up until one thousand years ago when it started to erupt far more frequently and then again 1947 as Henrik wrote.
      I do not think that Hekla is about to change to more infrequent eruptions at this point. At the same time the decadal intervall is a bit of an illusion.
      As mentioned, Hekla is not overdue. It is not ready to erupt yet, and when it is it will erupt. When that will happen is epically hard to predict.

    • Adopt or enslave us. At least my dog knows exactly how to make me move!

  24. I’m still wondering about the one the automatic system put at Askja. It has still not been manually revised. The drums do show something at 16:48. In fact, it is visible on drums almost all across Iceland, so some sort of event did take place at that time. It does not have the sharp initial snap of a tectonic quake and by judging from drumplot amplitudes it seems to originate from Bárðarbunga rather than Askja.

    30.08.2016 16:48:48 65,036 -16,840 0,9 km 3,2 62,08 11,0 km V af Dreka

      • I know, I do exactly the same 🙂 I keep a local copy of all quakes since 1995 and play around a bit with different plots, very similar to yours. I don’t have a good tool for plotting on a real map though, so I usually keep the plots for myself. Thanks for the tip anyway, and also thanks for your nice animations!

    • It has now been checked and changed to M2.2 at Bárðarbunga.

      16:48:43 64,683 -17,422 3,9 km 2,2 99,0 6,9 km NA af Bárðarbungu

    • It is not only you Tomas, but us as well as the people at the IMO who wonder about it. There was a similar quake almost a week ago that at first was a M3+ ~50-60% automated solution ~6 km north of Grímsfjall which was checked and assigned a M2.2 99.0% solution by the IMO and then almost immediately removed and never reinstated.

      There is also the 13:33:28 M3.8 yesterday at Bardarbunga that we still wonder about. It was awarded a very strange solution as but a single quake. On the Bardar drum, there was a very faint indication of a smaller and almost simultaneous quake, but at all the nearby stations, the Kreppuhraun drum in particular, it showed up as a twin quake of equal magnitudes with the same separation in time between the quakes (which indicates that its probably not just a reflection of the same initial seismic shock) and not with an an almost identical profile as all other large Bardarbungian quakes seem to produce.

  25. You guys rock! I should have known flights could be affected and based on Lady Eyaf’s contra indications I would guess that Katla might blow in a couple of weeks, when I am due to fly to France. When Eyaf sent her ash towards the UK I was due to fly from London to Spain. Glasgow airport closed, then Edinburgh, then York and Newcastle and I rang my holiday company and said I wanted to cancel my holiday because the plane would be cancelled by the time I had driven to the airport near London. The woman told me to go anyway and wait for the next available flight but I was able to tell her I suspected that that might be in 2 weeks time… She observed that the phones had been rather busy that morning – and I had my money back in full within the next 3 weeks! The whole country was in chaos so perhaps a lesson could be learned – any suggestions?

    And thank you for 2 brilliant articles, Albert. They should have left Pluto as a planet because the missing giant is already known as Planet X

    • Thank you! (BTW, the second article was Carl’s who I am sure will happily accept the compliment.) If Pluto was still a planet, quite a lot of other objects could have claimed to be a planet too, leaving the missing giant as something like Planet IIIVL.

      • Thank you!
        I could never have written Alberts piece, I loved it too 🙂

  26. Thanks for answering Há/Goðabunga question 🙂
    I have one more thing i am wondering about. The colour-warning-system, at this point, it is green – i wont hold you to your answer/s. We are just playing 🙂 – what is the next event that must/will take place for the colour to change level?

    • A prolonged earthquake swarm lasting several days containing a minimum of 100 earthquakes per day. There will not be a lot of tremor prior to onset of eruption, mainly the earthquakes will be tectonic with a few volcano-tectonic earthquakes in the mix.

    • Guessing here based on something a geologist was quoted as saying in the press recently when the large eqs occurred. The alert level for an imminent eruption will be raised when it is clear that magma is very close to or has reached the ice-cap. If I understood correctly, it is believed that the ice-cap can hold the magma for 1 to 1.5hrs, giving time to raise the alert.

      If the above is true, I hope Katla is kind enough to make it clear when the magma reaches the ice-cap.

  27. A new map with a new look that I am still trying out so please understand this is a work in progress.

    Suggestions welcome

    This map is only the Katla Caldera area for now and shows time lapse coloured by depth.

    Of note and I will try to make one for just the past few years, focus on the deep(dark) quakes on the east side that increase around 2013 and when you see the pulse of dark it is followed by swarm of yellow which is shallow. I think this clearly shows how the pulse rises up and creates the shallow quakes.


    • Love it! It ties in beautifully with something Lurking, Carl and myself worked out several years back (summer of 2012), so please, hang on to it!

    • I think it’s a great tool. After watching it cycle a couple of times, I found it most useful to use the pause/play button often so that my mind could absorb it a little better. Good work!

    • I especially enjoyed how it showed the deep swarms that occured previously under the area that is now active. In that speed it is obvious that we are indeed talking about deep swarms as magma moves into the system.

  28. Veðurstofa Íslands ‏@Vedurstofan 43s44 seconds ago Iceland
    Incr. conductivity meas. in Múlakvísl, gas measurem. show high concentr. of hydrogen sulfide. Do not to travel near river – gas pollution

    • The report also says :Do not measure sulfur dioxide by the river as previously thought.:

      If this is now just hydrogen sulfide being released does this point to a precursor to a volcanic eruption .

      Could someone please explain the difference between the two chemicals and what it may mean.

      • Both SO2 and H2S are volcanic gases. These are released when magma is near the surface and during an eruption. As Katla is covered in an ice-cap, any gases emitted can be trapped in the ice. Trapped gases are released when some of the ice melts (weather or magma activity-related), which is why the gas levels have gone up with the current increased water outflows.

        IMO has put in gas monitoring to analyse what is happening.

        A bit about volcanic gases from USGS:

        • Many thanks for the link just wondered if the difference between the chemicals meant if there was an eruption it may be more powerful.

  29. I’m a bit confused about something: the map of volcanoes on the IMO’s alert level page doesn’t seem to match the GVP database (for example, the IMO map doesn’t include Geysir). Why is there this difference?

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