After our ‘quantum Katla’ post, it is now time to return to the real Katla. For in the real world, Katla has been showing unusually strong shaking. It turned out that Henrik had already done much of the work for us. Here is a resurrected post from the dungeons of 2012 where young Henrik keeps our Katla feet firmly on the ground. It includes an addendum on the current activity.
Rest in peace, Henrik, and when Katla blows we will raise a glass to you. (Clive, 2019)
Part I
Katla is a relatively young volcano which like so many Icelandic volcanoes formed when Iceland was covered by ice. Hence it is a tuya, steep-sided with a broad, flat top. Like other large Icelandic volcanoes, it has a very large summit crater described as a caldera, but one that did not come about as a result of the collapse of the volcanic edifice into an emptied and very large magma chamber as happened at Mount Mazama a.k.a. Crater Lake in Oregon, at Krakatoa or at Long Valley.
Fig. 1. Herðubreið, a subglacially formed tuya with steep sides and a flat top. Post-glaciation, erosion has made the sides less steep and a small post-glacial cone makes the top appear less flat than it once was. The similarity to Katla, once you allow for the vast differences in size, is obvious. (extremeiceland.is)
One of the keys to understand what goes on at Katla is to have an idea of what lies beneath the up to 700 meters thick glacier that covers her crater/caldera. In schematic representations of Katla, a magma chamber at the very shallow depth of three to five kilometres is often displayed. From reading descriptions of other volcanoes that have suffered caldera collapse or looking up a general definition of ”caldera”, it is easy to assume that Katla too must have a magma chamber that spans the entire width of the “caldera” and which, “once-upon-a- time” collapsed to for the present-day caldera. Nothing could be further from the truth, but alas, there is no direct information available that accurately describes what Katla’s magmatic system, the true volcano, looks like. We have to fill this gap ourselves.
The first thing to do is to look at what she has done in the past. If we look up her “Eruptive History” on the Smithsonian Global Volcanism Program website, we find that Katla is listed as having had 27 eruptions during the period Iceland has been settled by humans, some eleven centuries and counting. Of these, only the larger eruptions seem to have been registered prior to the middle of the 20th Century. Thus the 27 eruptions are divided as follows: Two VEI 0 (1955 and 1999), three VEI 3, fourteen VEI 4 (including the AD 934 “Eldgjá fissure eruption”) and four VEI 5 with a further four not assigned a VEI number. Of the four unassigned eruptions, one is listed as “subglacial, lava flows” and three as “subglacial, explosive”. Please take note of the dearth of smaller eruptions, VEI 0 – 2, as this is important and something we’ll return to later.
From this information, it is clear that Katla cannot have a single, caldera-sized magma chamber because such a chamber would contain several tens to even hundreds of cubic kilometers of magma, which in turn would have led to far larger eruptions. None have occurred. Since VEI 5 is assigned to eruptions that eject between 1 and 9 cubic kilometres of Dense Rock Equivalent (DRE) explosively, and Katla’s VEI 5 eruptions are remarkably consistent at between 1.2 and 1.5 cubic kilometres, anything much larger than some 3 – 4 cu km is rather out of the question. A caveat – given the area covered by the crater/caldera, there could be more than one such chamber responsible for her eruptions, in which case it would be fair to ask the question if Katla really is a single volcano or if not a description of her being several volcanoes rolled into one would be more accurate.
If we look at her eruptive history prior to Iceland being settled, deduced by tephrochronology – ash layers deposited being identified by their physical properties, such as chemical composition and grain size, as belonging to Katla and from the size, distribution and time derived for each individual layer of tephra, an eruption responsible for it is inferred – we find that there have been a multitude of eruptions, but only a few of which have been assigned a VEI number. Interestingly in every such case a VEI 3 or 4 has been deduced. Anything much larger must have left such extensive deposits that such a huge eruption cannot have escaped detection, hence we can conclude that no explosive eruptions larger than a small VEI 5 have ever occurred at Katla.
There have been two exceptions to the rule that Katla’s eruptions normally are in the VEI 4 range volume-wise. Both originate on her NE flank, outside the crater/caldera. Around 5550 BC, Katla was the source of the 5 cubic kilometres “Hólmsá Fires eruption” lava flow. In 934 AD, the four times larger “Eldgjá eruption” spewed forth some 18 cu km of lava and five cu km of tephra, or ash. Even if the total volume erupted in 934 AD, about 22 cu km DRE, is on the order of 50 times greater (25 to 200 times), a lowly “VEI 4?” has been assigned.
As the underlying causes and processes that drive “regional fissure eruptions” are vastly different and as they happen very rarely, seemingly with a time interval measured in several millennia in the same-ish location, fissure or rift eruptions should be considered separately – even if the visual appearance of the Katla crater/caldera suggests that a fissure eruption has at some point in the distant past intersected it. They are mentioned here because an article such as this cannot fail to do so, nor can it fail to give a reason why they are not included in the discussion.
Earlier I mentioned the apparent absence of small eruptions from her eruptive record with only two “possible subglacial eruptions” in 1955 and 1999 listed, to which can now be added the equally suspected or “possible” July 2011 subglacial eruption. As I write this, it seems that there may have been yet another, very minor hlaup. That such eruptions were not noted in earlier days is not surprising as the very small hlaups they resulted in were local nuisances rather than regional catastrophes of a major Katla jökulhlaup and would not have been seen as important enough to be recorded, even had they been observed. But how frequent could this type of small eruption be?
Fig 2. Seljansfoss Waterfall during the 2010 Eyjafjallajökull eruption (Binaural Waves Blogspot). Notice evidence of several minor eruptions on the mountainside above the waterfall.
We know from the 2010 Eyjafjallajökull eruption that it was preceded by two fissure eruptions at Fimmvörduhals that intersected each other. If we look at the topography and geography of Eyjafjallajökull, we can see many areas of monogenetic cones. This indicates that eruptions of the Fimmvörduhals type greatly outnumber eruptions at the main vent. At Askja, a similarly sized volcano albeit glacier-free and with a slightly smaller summit crater/caldera, there have been six small eruptions since the great eruption of 1875 and many prior.
Of the 24 eruptions (not counting the AD 934 Eldgjá fissure eruption) listed before it was realised that there were smaller eruptions that would only show as minor jökulhlaups, 20 are listed as VEI 3 or higher and three of the four not assigned a VEI number are listed as (subglacial and) explosive. At least 17 of the 23 explosive eruptions have been assigned a VEI of 4 or 5. The eruptive record of Katla thus indicates that in order to break through the up to 700 meters thick Mýrdalsjökull glacier, an eruption would need to be at least as powerful as to merit a designation of VEI 3. Thus – the reason for the dearth of smaller eruptions observed is that they are not energetic enough to break through thick glaciers such as Vatnajökull or Mýrdalsjökull to be visually obvious and the minor hlaups resulting have been much too insignificant to have been considered as a result of an eruption that never was seen.
Fig. 3. Pits formed by melting from below in the Katla glacier, summer 2011. The glacier was still covered with tephra from the Eyjafjallajökull eruption which made such features stand out unusually well. (ModernSurvivalBlog, picture may originate with Icelandreview)
With the advent of aircraft, it was noted that there were pits in the glacier as if it had melted from below and the collapsed to form an ice crater. These pits are relatively numerous and vary in size. They have been explained as due to either strong hydrothermal activity or, in the case of the larger ones, as the result minor subglacial eruptions.
The obvious conclusion is that in the case of Katla, small eruptions of the Fimmvörduhals type far outnumber the bigger, recorded eruptions. This is vital for understanding how a volcano such as Katla is built and works.
Let us for a moment return to what I like to call “Katla’s defrosted twin”, Askja. Here we can see, side by side, the effects of the two types of eruption. In 1875 she had the big VEI 5 eruption, about four times as great as Katla’s historic VEI 5s, that would eventually form lake Öskjuvátn. Here we have a magma chamber where magma collected over time, partially re-melting and absorbing the chamber walls which together with fractionating led to the body of magma collected being far more silicic than the basalt injected into the chamber, which provided the heat or energy for the process. This went on for centuries, quite likely millennia as GVP lists the preceding very large eruption at Askja as having occurred about 11,000 years ago, until a final basaltic intrusion was energetic enough to unbalance the magma chamber and the big eruption of 1875 followed. Please note that both before and after, there have been many smaller, basaltic eruptions that have evidently bypassed the main magma chamber on their way to the surface, one of which caused the miniscule crater Vítí located immediately north of Lake Öskjuvátn
Fig. 4. “Katla’s defrosted twin”, Askja. Aerial photograph inside and above the Askja caldera with Lake Öskjuvatn and the miniscule crater Viti barely discernible on the near left-hand side of the lake. (uwmyvatn blogspot)
This too is what I believe must have been happening and is going on at Katla. Sturkell and his co-authors in their 2009 paper “Katla And Eyjafjallajökull Volcanoes” note that the products of Katla’s eruptions are bimodal, comprising alkali basalt and mildly alkalic rhyolites “with intermediates very subordinate”. One, or possibly more magma chambers where magma collects, fractionates and grows more silicic, a process that takes hundreds if not thousands of years which is why more than one magma chamber seems to be required in order to account for the relatively frequent eruptions of Katla, until there eventually is an eruption of “mildly alcalic rhyolites”, accompanied by tens to hundreds of smaller, alkali-basaltic eruptions which due to their location under the ice in a watery environment, gouge out small craters and fill in the bigger ones with mostly small, broken fragments of lava, piles of pillow lava or even small lava flows or easily eroded cones. When a big eruption occurs, the glacier first closes the wound, then the crater gets back-filled with loose rubble which gets pasted over with more solid lava flows from later eruptions.
This process has been going on for as long as Katla has existed. Not only has this constant remodelling inside the crater/caldera left a kilometres-deep zone of clastic, i.e. broken or fragmented, rock mixed with water, it also in my opinion explains how the caldera was formed in the first place. This layer extends down to not much above the roof/-s of the magma chamber/-s. As freshly injected basalt from the mantle makes its way up, it will eventually encounter this water-rich zone and result in intense activity, hydrothermal at first, and if the intrusion continues, hydromagmatic. It is primarily this activity we see when we look at the tremor charts of the SIL-stations surrounding Katla, in particular the one located at Austmannsbunga, on the north-eastern crater/caldera wall.
In the next instalment, it is time to take a look at Katla’s neighbours Eyajafjallajökull and the Gódabunga “cryptodome” and try and separate their activity from that of Katla so that we can finally figure out what she may have been up to over the last few years and how likely an eruption in the near future could be.
Part II
It is now time to have a look at what’s going on and try to paint a coherent picture of what she actually is, is up to and able to do, but first let us recapitulate what we found previously:
- There is a general interest in Katla because she is and has been regarded as a very dangerous volcano by generations of Icelanders.
- The presentation of Katla in media is skewered by vested interests ranging from scientists who hope to increase their professional and/or public standing, people trying to cash in on the interest generated such as journalists and bloggers, and finally, there are people trying to increase their standing within the subculture of doomsaying and alarmism.
- Katla is a massive but relatively young volcano, located on the MAR, and formed when Iceland was covered by glaciers.
- The records include two large fissure eruptions on the NE flank of Katla; the prehistoric 5 km3 Hólmsá Fires of 5550 BC and ~22 km3 Eldgjá eruption in 934 AD. In historic times, the 1100 years or so that Iceland has been settled, there have been 27 listed eruptions (28 if the inferred minor subglacial 2011 eruption is included), 23 of which have been explosive.
- Of the 23 explosive eruptions, three have been assigned VEI 3, thirteen VEI 4 and four VEI 5.
- The four VEI 5 eruptions are remarkably alike in size at 1.2 – 1.5 km3, which is at the upper end of what Katla probably is able to do but at the very lower end of VEI 5 eruptions.
- Tephrochronology (in some cases complemented by radiocarbon dating) has identified a further 103 eruptions going back ~8,500 years, and in the few cases where a VEI has been assigned, none have been greater than a VEI 4.
- Katla does not possess a caldera-sized magma chamber.
- In order to account for the great number of explosive eruptions which involve more evolved magmas, Katla could have more than a single magma chamber.
- The available evidence suggests that in order to break through the up to 700 meters thick Mýrdalsjökull glacier, an eruption must be at least a substantial VEI 3.
- Direct and (primarily) indirect evidence suggests that smaller eruptions, mainly basaltic VEI 0 – 2 eruptions are severely underrepresented in her eruptive record and ought to exceed the number of observed eruptions.
Fig 5. Mýrdalsjökull showing the main glacier outlets, directions of jökulhlaups and areas affected. E – Entajökull, S – Sólheimajökull, K – Kötlujökull, M – Markarfljot, Ss – Sólheimasandur, MS – Mýrdalssandur. Eyjafjallajökull is to the left and the smaller glacier above is Tindfjallajökull (adapted from Google Maps).
The greatest danger from Katla comes from the very quick and extensive melting of the glacier caused by large eruptions which results in destructive jökulhlaups. There are three major outlets from the glacier: Entujökull to the NW that empties into the Markarfljot river and valley north of Eyjafjallajökull, Sólheimajökull to the SSW that empties onto the Sólheimasandur and finally, Kötlujökull to the SE that empties in a great arc east through south onto the Mýrdalssandur. What ought to be prime farmland and in fact once was settled, is nowadays an unsettled wasteland because of the devastating jökulhlaups unleashed by Katla. This is the true reason why Katla is considered to be such a dangerous volcano.
The fact that one often comes across the reference that in the days before the Hringvegur (ring road), “people were afraid to traverse the Sólheima- and Mýrdalssandur because of the frequent jökulhlaups” is another indication that smaller and unrecorded eruptions that cause only minor hlaups are far more frequent than the 40 – 80 years often given as the interval between main, and thus visible, eruptions.
Fig. 6. The foundations of the old bridge across the Múlakvísl river destroyed by the July 9th 2011 jökulhlaup are visible to the left. The new bridge was laid down a week later. (photo John A Stevenson, GVP website)
Apart from the postulated connection between the Eyjafjallajökull and Katla volcanoes, one question that always crops up is the Goðabunga cryptodome. Many volcanologists maintain that it is a part of the volcanic system of the Katla central volcano. Others, notably Sturkell and his co-workers, claim it is part of the Eyjafjallajökull volcanic system. In order to shed some light on this issue, I asked our own GeoLurking if he could make a plot of all the earthquakes from 1994 up to and including the 2010 Eyjafjallajökull eruption. The results are quite clear and do throw up a surprise:
Fig 7. E-W cross section, view from south, through Eyjafjallajökull, Goðabunga and Katla. Plot by and courtesy of GeoLurking. The “lines” formed at approximately 5, 3 and 1.1 km at Goðabunga and Katla are most likely artefacts caused by quakes being assigned a poorly defined depth. The latter, 1.1 km, is the default depth assigned by the automatic system in case it cannot compute a depth within the predetermined level of certainty and unless they are manually checked, which is not the case of every quake, automatic depth remains uncorrected, hence these artefacts.
From this cross section, it is quite clear that there is no connection between the Eyjafjallajökull volcanic system and Katla. Eyjafjallajökull has its own, well-defined feeder system from the Moho (first molten layer beneath the Earth’s solid crust) as does Katla, thus they are wholly independent of one another. As can also be seen, albeit not as clearly, Goðabunga too seems to be independent of either Eyjafjallajökull and Katla, the ramifications of which will be the subject of a later post by Carl. Sufficient to say that when we contemplate what Katla herself may be up to, we must differentiate between activity at Goðabunga and activity at Katla. Once we do, we see that while Goðabunga is more or less continuously active, Katla operates in bursts and seems to be most active during summer and autumn when the ice cap is at its, relatively speaking of an up to 700 m thick glacier, thinnest.
Fig 8. Activity post-Eyjafjallajökull. Activity at Eyjafjallajökull is minor and has to do with the system settling down after the end of the eruptive phase. Note that at a depth of 0 to 5 km or so, there seem to be three separate areas of activity at Katla. (Plot by and courtesy of GeoLurking.)
After the Eyjafjallajökull eruption, Katla seems to have entered an active phase with a suspected subglacial eruption on July 9th 2011 and several pits or craters forming on top of the glacier. This activity seems to be localised to three main areas within the caldera:
Fig. 9. Earthquake activity at Katla July 9th 2011, the day of the jökulhlaup and suspected subglacial eruption. Both the 1823 and 1918 eruptions occurred close to but just east of this area. The 1823 eruption occurred close to the easternmost red spot while the 1918 eruption was roughly at the rightmost dark blue spot below it. (IMO)
Fig 10. Earthquake activity at Katla July 17th 2011. (IMO)
Fig. 11. Earthquake activity at Katla July 21st 2011. The 1755 eruption was situated in the same area as the three overlapping orange spots.
As can be seen, there are at least three distinct areas of activity inside the caldera with the one associated with the inferred July 9th eruption well to the south. The pits formed in the glacier also align with these three areas, albeit the pits to the northeast seem more drawn out along the caldera wall and not over the center of activity. These three areas seem to tie in with the three areas of activity noted in fig 4 as do the locations of three of Katla’s major eruptions. Thus there is not a single vent, but at least three at surface distances of approximately 5 to 8 km from each other. It is equally likely to judge from Fig 7. and Fig 8. in conjunction, that at great depth, they do have a common source.
I will now present you with my personal view of Katla, but do not be afraid to disagree or draw your own conclusions (within reason please, no Katlatubos here):
Katla is a young volcano and far more active than has previously been thought. Unlike the similarly aged but much less active Eyjafjallajökull, Katla has had more time to develop her system of sills to the point where they are fewer in number than they originally were but have a substantially larger magma-carrying capacity and approach or may have reached the point where they can be considered magma chambers proper. Since cooking evolved magmas takes a long time, usually millennia in the case of cubic kilometre-sized silica-rich magmas and at the very least many centuries for intermediate magmas, it is highly likely that Katla possesses several pockets of magma capable of eruptions ranging from high VEI 3s to small VEI 5s. Not only do the times between such eruptions argue this, their wide spread of location within the caldera does so too.
The most common type of eruption at Katla is the small, subglacial eruption of a few tens of millions of cubic meters of basaltic magmas. These eruptions are not energetic enough to break through the very thick Mýrdalsjökull glacier and the only proofs of their existence are intense earthquake swarms followed by minor jökulhlaups and later observations of deep pits or craters, sometimes water-filled, in the glacier ice. My guesstimate is that there may be many such small eruptions over any given ten-year period, and possibly in the case of a period of high activity, there may even be more than one in a single year. By back-tracking and investigating old accounts over the past few centuries of jökulhlaups in the area not associated with visible eruptions, it ought to be possible to identify many of these minor eruptions.
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.
Finally, what we do see when we look at SIL-stations such as Austmannsbunga, located on the NE caldera rim (not a coincidence, see above), is hydrothermal activity following a period of possibly still ongoing magmatic intrusion and not signs of an imminent, large eruption.
Fig 12. Hydrothermal activity at Katla as shown on the Austmannsbunga SIL (IMO) (Source: https://icelandgeology.net/?p=3291)
I’m sorry to be such a boring old fart, but if this is unsatisfactory, start looking for intense earthquake activity at some 25 – 10 km depth, showing on the IMO map for Mýrdalsjökull as being in the Eastern to Northern part of the caldera, activity that shows a clear upwards trend and spreads when it reaches depths approaching 5 km!
HENRIK, May/June 2012
Addendum
Henrik wrote this in 2012, after the burst of activity at Katla in the summer of 2011. It is now 2023 and we again had an earthquake swarm at Katla. And again it happened in summer. The activity occurred on 30 June, and was all shallow but far larger than might be expected of normal summer activity caused by ice melt. The strongest earthquake was M4.4 and around 10 quakes were M3. Not huge, but significant.
The swarm continued events from 4 May when there was an earlier swarm in the same general area. That swarm was a bit stronger with three quakes of M4. It briefly caused the status of Katla to be set to ‘yellow’ before returning to ‘green’ which it still is. That sequence was rather uncommon for early spring, normally a quiet time for Katla! Katla comes to life in summer. The last time a similar (albeit weaker) swarm occurred in Katla was in September 2016.
Was there any sign of an eruption? If we look at the tremor plot, a bump in blue line is evident on June 29. It is weak but otherwise similar to what was seen in 2011. The peak frequency of 2-4 Hz can be associated with glacial floods, i.e. increased ice melt. A magmatic eruption (bubbly magma moving up in the conduit) would normally show up equally at all three frequency ranges. However, this particular bump occurred a day before the earthquake swarm so is not directly caused by the shaking.
June 2023, Katla
It is worthwhile looking underneath the ice. Katla has a distinct caldera with a deep central depression, a steep rim which has three gaps where water can flow out, and several flow channels feeding the surrounding rivers. The ice cover reaches 700 meters thickness near the northeastern rim. About half the icecap lies above the caldera; a similar area of ice covers the northeastern slopes. The caldera shows geothermal activity. This is nicely shown by the icecap which contains several cauldrons where the heat has melted some of the ice. The hydrothermal activity is mainly located just inside the caldera rim, along the western and eastern edge. This suggests that the heated water is circulating via the ring fault. There are also two active areas within the caldera.
The ice-free caldera map. This view is from the southwest. Image from Helgi Björnsson et al, 2000, Jokull 49, 29 (https://www.researchgate.net/publication/285499559_Surface_and_bedrock_topography_of_the_Myrdalsjokull_ice_cap_Iceland_The_Katla_caldera_eruption_sites_and_routes_of_jokulhlaups).
High resolution map of the caldera. The circles indicate hydrothermal activity. North is up. Image source Björnsson et al.
The recent earthquake swarm was located just inside the northeast rim of the caldera (see Jon’s post: https://icelandgeology.net/?p=11319). The swarm in May was in the same area. The caldera map shows a narrow gorge just outside the caldera, which curves a bit but generally runs north-northeast. This is the rift that fed the Eldgja eruption. The swarm was located a little south of there, within the caldera. Rest assured: last week’s activity had no relation to Eldgja!
Previous activity after the large 1918 eruption occurred on 25 June 1955, 17 July 1990 and 8 July 2011, all in the caldera. All three were hydrothermal events where magma was either not involved at all or was only a minor byproduct. Notably, all were in the summer, which clearly indicates that they were driven by summer melt: Katla is a summer volcano. We might even call it an august volcano, fitting both its size and seasonality. (The eruption of 1918 though was on 12 Oct, showing its magma is not limited by the season.) In 1955, two ice cauldrons formed on the southeast rim and a small jokulhaup occurred. In 1999, the activity was on the southwest rim with tremor and a jokulhaup. The 2011 activity was larger, with strong tremor, earthquakes in the south and east of the caldera up to M3.4, and a jokulhaup which swept away a bridge. The effect was likely amplified by the fact that water had accumulated in the caldera over the preceding year, causing uplift of the icecap.
The 2023 activity fits with these events. The location is a bit north of the 1955 event. The earthquake activity was stronger but it has not caused a jokulhaup – perhaps because the location is a bit away from the immediate drainage channels.
Was it an eruption? Or perhaps a precursor? Katla is a mysterious beast. It has much to hide – it keeps its icecap for a reason.
There is in fact no evidence that the earthquake swarm was related to an eruption. There may have been a small hydrothermal event, as evidenced by the sulphur smell around the rivers. This may have preceded the swarm. However, the size of the earthquakes and the fact they followed on from a similar swarm from two months before does suggest a pressure change around the ring fault. That could be coming from a dike or from increased water circulation. The time of the first swarm may make the first possibility more likely, at least for that event. Perhaps it was the continuation of the intrusions from the deep which happened a decade ago. If you want to know, see the second link below.
My guess for now (and it is only a guess) would be that the earthquake activity is related to (but not coincident with) a small hydrothermal event. — which may not have happened yet! This may be or may become one of Henrik’s missing VEI 0’s. Whether it will become anything more is just a matter of wait and see. Katla is still a quantum volcano – it remains impossible to predict.
Post by Henrik, May 2012; addendum by Albert, July 2023
I submit this technical paper as an interesting read of the previous Fagradalsfjall dike intrustions and subsequent fissure eruptions – see https://www.authorea.com/users/535743/articles/600244-dike-segment-propagation-arrest-and-eruption-at-fagradalsfjall-iceland
I am hoping for some comment on the continual 5 km or so earthquake activity near Keilir as to dike propagation and what might lie ahead.
“New data shows that magma is less than one kilometer deep. The flow of magma is considerable. These are strong signs that an eruption may be imminent.”
https://twitter.com/RUVfrettir/status/1677081633902546945
Fréttastofa RÚV is what type of organization? I don’t have full access to twitter, sorry.
Icelandic national radio/news station
RÚV = Ríkisútvarpið = Iceland’s national public-service broadcasting organization.
By imminent I hope they mean tomorrow! Saturday is more likely though as I have family visiting for the day and although they slightly inderstand my obsession with volcanos I will still spend most of the day in the kitchen. 🙁 🙁
So many thanks to the person who developed the laptop. I shall have it open whilst cooking if an eruption occurs!
As a tourist eruption it should start on weekend … and with daylight unlike many Hawaii eruptions which prefer to start in dark night.
https://www.ruv.is/frettir/innlent/2023-07-05-kvika-a-minna-en-eins-kilometra-dypi-386976
(I personally prefer Google’s Scandinavian translation that are more close to original Icelandic)
Magma is now between Lilta-Hrútur and Litli-Keilir. A scientist says that some more magma than last time is on the way. He assumes that magma nears the surface.
So after one day we have deformation 18cm, greater then 16cm, after two days of unrest in august 2022.
I submit this technical paper as an interesting read on the dike formation at the Reykjanes Penisula area. See https://www.authorea.com/users/535743/articles/600244-dike-segment-propagation-arrest-and-eruption-at-fagradalsfjall-iceland. It would be very interesting to obtain comments on this 3rd or 4th dike emplacement in the region and what might lie ahead?
Interesting is that the pause since 2022 has the same duration as 2021 to 2022: 11 months! The first eruption ended in September 2021. The second eruption was in August 2022. The third eruption is very likely in July 2023. So still some kind of regular magmatic behaviour like a lava geysir …
How well can we compare the Fagradalsfjall Fires (until now) with the Krafla Fires 1975-1984? The Krafla fires were more irregular with different long breaks. But there was more movement. Many intrusions had heavy deformation (up/down) but were without extrusions. Fagradalsfjall until now hasn’t had a similar deformation like Krafla. Many eruptions of Krafla Fires only lasted hours, while Fagradalsfjall’s eruptions were much longer.
But Krafla Fires had the biggest eruption in the end: The last eruption 1984 was two weeks long. This shows that a Fires Series can have the biggest eruptions in the end, and Fagradalsfjall might do the same. But we’ll have to wait for future to find out more.
After watching several more quakes pile in from the Eidey area, perhaps they are not so accidental as we assume? It is getting harder to avoid coming to the conclusion that in some way the earthquake activity in the Fradgradalsfjall area might be triggering the activity in the Eidey region. We all know that they are separate regions, geographically. But perhaps they’re not so separated dynamically in regard to plate tectonic stresses?
It’s difficult to differ between real quakes at Eldey and “Ghost quakes” which are wrong localized earthquakes by the digital monitoring system. From Snæfellsnes to Myrdalsjökull are many earthquakes on the wrong position which belong to Fagradalsfjall’s swarm.
However, it would be exciting if both volcanic systems make eruptions. We don’t know what Eldey did during the initial phase of the Middle Age volcanism on Reykjanes peninsula. An eruption there wouldn’t be as spectacular as Fagradalsfjall, but would also be interesting news.
It does look very vigorous. I am wondering whether the Eldey thing might actually be a second dike intrusion along the MAR. That certainly would improve chances of an eruption. Cant check in detail though because I’m not at home.
Is there a rifting event going on along the MAR?
On the Reykjanes ridge map that zooms out a bit to show the submarine part, the Eldey area is just as swamped with earthquakes as Fagradalsfjall. It is too zoomed out to see much detail but I cant think of what these quakes would be if they arent another dike, the peripheral quake swarms of the last two eruptions were much closer to Fagradalsfjall, mostly around Grindavik (and above the intrusions of the same area) and under Kleifarvatn.
Eldey is a long way away from Fagradalsfjall, if it is a peripheral swarm then that means the area of affect of fagradalsfjall has gotten multiple times larger. Either that or it is a second dike. Neither is a prticularly good option really, if Fagradalsfjall throws a curtain fo fire eruption out of the blue it could be lethal to anyoen nearby, and would likely sever the Keflavik-Reykjavik road. If Eldey is a new intrusion it mostl ikely means a shallow submarine eruption will happen within a few years and basically as close to the airport as is possible. And if it is a slower eruption then it might end up beign far worse than Eyjafjallajokull was, at least locally. If it is a fast eruption well then it could well become a VEI 4.
Maybe all a bit of exessive speculation but things are really taking a turn that they didnt last time, this eruption might turn out to be not so tourist friendly as the last two…
Since April the whole western peninsula rose with 1cm/month (totally 3 cm) according to last weekly report of GVP. This inflation is larger than Fagradalsfjall alone. It may be part of the general awakening of the Reykjanes peninsula.
Another possible development at Fagradalsfjall is the building of a magma chamber. They say that 15 km below magma is accumulating. This magma chamber might be the condition for a sustainable shield eruption.
It looks like a new burst of activity, multiple 3+ quakes off the southwest Icelandic coast now
optical illusion?
7h05 (Geneva)
https://www.livefromiceland.is/webcams/reykjanesviti
eruption has started?
sorry i didn’get enough coffe….
It was a hauntingly beautiful sunset tho!
*Closes Reykjanes peninsula map*
*Opens Reykjanes ridge map*
*Holy heck!*
OK, I’ve no idea what’s going on there. Answers on a postcard! Or I’ll ask Sigrun!
Magma is trying to ascend in the Fagradalsfjall – Kelir area (no idea where/if it will emerge). InSAR confirms a dyke between the 2. Weaker curst from earlier activity means things are now moving faster than before?
Lots of ghost quakes but activity to the west (eg Eldy) and the east could be due to the crust accommodating the inflation. Whether or not this lets magma out at other locations is anyone’s guess at the moment.
Replying to
@gislio
The latest measurements show that magma is now at a depth of about 1km. Furthermore, the reservoir of magma collecting is larger than in the last eruption, pointing to the potential of a more powerful or longer eruption. 300+ quakes from midnight to 4am GMT.
The hills/mountains in the area show the weak spots in the rock, that were vulnerable for magma extrusions during last activity 8000 years ago. I’d assume that these weak structures still remain and are likely eruption sites.
Sending you an empty postcard .. or one in erasable ink. The Eldey swarm is deeper (6-10 km, mainly) so I assume a deeper dike (sill) is forming here. Simultaneous eruptions would be fun – with the airport in between, passengers should get exciting views! Fagra is further along to an eruption though. I give that a day
1989 Eldey had the last volcanic submarine activity: https://volcano.si.edu/volcano.cfm?vn=371022#bgvn_198905
Afterwards they found a new submarine lava field. The eruption was too deep to cause any thermal anomalies on the surface.
Do we for a fact know that the Eldey swarm is magmatic?
Not absolutely confirmed but the evidence is overwhelmingly likely. Although the chance of it erpting in the immediate future is not so much.
Great Sitkin is clearly active: “Lava continued to erupt slowly at Great Sitkin over the past week, adding to a thick lava flow confined to the summit crater. Multiple satellite radar images this week showed that the lava continues to slowly move to the east into the intracrater glacier.” https://avo.alaska.edu/activity/report_getter.php?need=current&id=403860&type=4
Currently the most active volcano of USA.
I was watching the Litli-Hrutur webcams this morning when a 3.45 mag quake at 08:53:26 am local Iceland time hit right at Keilir. I caught the camera vibrating for about 1.5 secs about 2-3 secs or so after the given time of the quake, so it took about 2-3 secs for the pressure wave to travel over to the camera. It was kind of fun seeing the camera picture skewing around a bit as it vibrated. Another quake at 9:17:34 mag 2.4 also jiggled the camera a bit too. See https://www.youtube.com/watch?v=_q1N4J5oTSE and https://www.youtube.com/watch?v=yJfiMhqLgTY for the views and if you back the view up to 08:53:26 am you can see the camera jiggle at the 08:53:28 am or 08:53:29 am mark.
Okay, a 4.78 mag quake hit at 09:37:54 am local time and this time it knocked the video feed down for the north Litli-Hrutur camera exactly 7 seconds before the actual quake occurred. I made a video of these events. The south camera was panning up and lost the feed for about 10-15 secs entirely. I think it is remarkable that the video feed is knocked down 7 seconds before the quake hits. See https://www.youtube.com/watch?v=yJfiMhqLgTY and scroll back to the 09:37:00 am mark and carefully watch.
Thanks for that Randall. I have ‘felt’ an earthquake on a simulator but to see one happen in real life was great. So I enjoyed watching even if it has spoilt the view of Keilir. 🙂
Here ya go…while you’re watching..
https://twitter.com/EIlyinskaya/status/1677249089484759041
Earthquake activity diminished at Fagradalsfjall in the last 24 hours. Perhaps counterintuitive but this is what happened shortly before the eruption started both in 2021 and 2022. Magma is now at < 1 km depth. Help us monitor the area with the webcams!
well, the north and south Litli-Hrutur cameras are rocking and rolling.. the mag 4.78 quake at 09:37:54 am local Iceland time was a good one!
Friday
07.07.2023 09:37:53 63.946 -22.173 4.7 km 4.8 99.0 0.5 km N of Keilir
I was watching both Litli-Hrutar cameras and the Skjalfti2.0 quake monitor when that quake hit.. pretty exciting morning for me.
We currently have interferrograms that show that inflation is enormous and the elevation is already 18 cm with a maximum between Fallgradsfjall and Keilir.
So there is lots of magma avaible for eruption, perhaps coud form a shield now? Like a Mauna Ulu? The intrusion does not seem fast enough for a Kapelluhraun or Ögmundahraun like flow
It’s not 18cm uplift. The interferogram measures movement towards/away from the satellite. In the “wings” of the butterfly pattern there is uplift as well as lateral movement away from the dyke. The “body” of the butterfly actually shows subsidence, as the support is removed when the sides of the dyke are pushed away. The maximum displacement is in the left “wing” where both the uplift and the lateral movement is towards the satellite.
Magma is less than one km underground now so eruption is perhaps certain in the next few hours or day
…Chances of a more powerful eruption than in recent years. Magma influx is 88 M3/s (34, 49 in 2021. 2022)..
Chances are that if magma breaks its way to the surface now and an eruption begins, that eruption will be more powerful than the eruptions on the Reykjanes Peninsula in the last two years. At least to begin with. This is what Lovísa Mjöll Guðmundsdóttir, a natural hazard expert at the Icelandic Meteorological Office, says.
“We were running a model that shows us that magma inflow into the magma tunnel is 88 cubic meters per second.”
Lovísa says this is a much faster inflow than was measured shortly before the last two eruptions. Shortly before last year’s eruption, magma inflow into the magma vent was measured at 49 cubic meters per second, and shortly before the 2021 eruption, it was measured at 34 cubic meters per second.
Lovísa says this indicates that if magma breaks through the crust now and an eruption begins, it will be considerably more powerful than the other two, at least at first.
https://www.ruv.is/frettir/innlent/2023-07-05-afram-skelfur-jord-en-ekkert-bolar-a-gosi-386976?fbclid=IwAR09U9PpgwbN_yORHX-vMXifrgvuo_mx4thgVD7MhdJXHhme_NJK_54vT1o
This cam is probaly the right place to watch when it erupts
https://m.youtube.com/watch?v=yJfiMhqLgTY&embeds_referring_euri=https%3A%2F%2Fwww.ruv.is%2F&source_ve_path=MjM4NTE&feature=emb_title&fbclid=IwAR00Sk-x9aFyCyaK0aBLU4mK4CDR3S7rb0H0X5z0Q2WBnl18rUIM9P1a0rA_aem_AYOxRoBGJ57FnbtTiSUNN-cWBKa-NC4r1xx3zNKpAz_Ui0-8ANgUgCtZdE3w6kKZkd8
Magma is less than one km underground now the chance of eruption is quite certain now
I haven’t seen anyone mention this but if #Fagradalsfjall erupts today then there is a weirdly precise interval of time between eruptions. 319 days passed between the 2021 and 2022 eruptions, and its been 320 days since the 2022 eruption ended.
https://twitter.com/Tetraheedra/status/1677262568090468355
I do wonder the degree to which Fagradalsfjall is just the current location of Reykjanes eruption cycle or something bigger. Like yes the whole peninsula is heating up, but it may have just driven Fagradalsfjall to a critical point not reached in a long time. Does it just have its fair share of the magma from the last 800 years? Or does it have much more. Maybe not 10X more since presumably the reason it sealed shut would be it wasn’t staying active enough and also magma may have sort of seeped out the sides so to speak to other systems. If so could see this pattern continue. As infrastructure is built on the way up and 15km down the eruptions start ever more intense. Eventually a true fires or maybe a longrunning relatively high-rate shield eruption. Svartsengi does seem a *bit* far from Krysuvik compared to the other systems, supporting Fagradalsfjall being a separate system especially as it is pretty much exactly in the middle between them.
Reykjanes got ~3km^3 erupted last cycle. 1/4th of that times 10 is 7.5 km^3. However as mentioned losing to competitors and maybe lower rate anyway suggest might be lower. On the other hand the lack of a complex underground system means a larger % should erupt than for some other systems. But anyway seems in theory plausible by the time this sorts out that the area around Fagradalsfjall has picked up a few km^3 of rock.
This was my thinking back in the first eruption, now that therehas been another since, and very likely a 3rd imminent, it does seem that we should expect the area to look very different in the near future. I was my prediction that Fagradalsfjall would be the most active volcano in Iceland by far in the 2020s, and so far that has been true. Really, given that in the middle ages the Reykjanes and Krysuvik fires both lasted for about 30 years each it is not unreasonable to expect something liek that at Fagradalsfjall now.
The thign about shields is that before they become shields they become a gushing open conduit, usually with high fountains. Think Pu’u O’o or Mauna Ulu, before they became shields they had massive fountains, Pu’u O’o was basically a small stratovolcano by the end of 1986, its north side was never buried by later flows even. And that was at 4 m3/s average, Kilauea now might be at double that sort of supply. And even that pales in comparison to what we might see now.
The other really big unknown is whether fagradalsfjall is capable of the same sorts of high intensity fissure eruptions as Krysuvik, Svartsengi and Hengill. Hengill is known to posess some sort of mature magma chamber as it has at some point erupted lava that isnt basalt. It is kind of a smaller and calderaless version of Bardarbunga. But Krysuvik also erupts liek this and it has no rela evidence of any shallow magma apart from some geothermal activity. The same goes for Svartsengi although the geothermal activity there is far more substantial.
I had been under the impression that sills would pool in the upper crust in these areas before rupturing anf flooding out all at once. This might be the case at Svartsengi with all of the intrusions under Thorbjorn, Svartsengi is literally the black plains, it is flat. But Krysivik hasnt got very conductive terrain for sill formation, it is very steep and with deep valleys and faults, sills form better in flat areas. If Krysuvik instead stores its magma deep down to erupt most of it all at once in a lava flood then Fagradlasfjall would be the same, with the 2021 eruption being kind of accidental from the first intrusion actually erupting which is somewhat atypical, and because it has been left out for millennia. The fact the entire peninsula has uplifted and each eruption and intrusion has become more intense than the last might support this interpretation. It will be interesting to see if the magma this time around is still ultra primitive mantle melt like 2021 or if it has signs of crustal contamination that would indicate storage.
The even area around Keilir is the peak of a great shield volcano with a height up to 238m above sea level. It’s possible that Fagradalsfjall builds a magma chamber which can once in the future feed such a shield eruption. The coming 2023 eruption is supposedly one of many steps towards this shield eruption.
Its seems there is actually a dike under edley. It stayed deep but it is very noticeable on the 3d plot. Also the dike under kelir has a horizontal feature. Maybe the magma drained into the rift?
https://skjalftar.is/3d/
https://twitter.com/gislio/status/1677308530775281664
Great update from the Volcano and Natural Disaster Center at
@Haskoli_Islands
including a map of potential eruption locations and lava flows
1/2
Awful! Lahar from Semeru in Lumajang this afternoon. It has also destroyed the Regoyo Lumajang Bridge 😱👀
10 days of continuous rain and there’s still no sign of it letting up 😩
https://twitter.com/volcaholic1/status/1677280772414230528
https://twitter.com/volcaholic1/status/1677281810869305344
https://twitter.com/volcaholic1/status/1677119116052668416
Although we are facing a rather disappointing volcano, I have to say that there appears to be steam in the hill to the left at 32:58.
I might be wrong.
Correction, sorry, the camera glass is dirty.
I’d guess that the “steam” is an meteorological inversion with some fog.
https://vafri.is/quake/?fbclid=IwAR33oDkBG7cpWKJ8Ca-6uEHi6RYRZ0w9WQdUoVA5IRzzwemvwWmBMb9QA2A#close
Not sure if all of these are completely verified, but the biggest cluster of quakes that are less than 2 km depth is basically right underneath Litli Hrutur. I believe that the live cam that is the main stream on RUV as well as the AfarTV stream on youtube, is on Litli Hrutur… 🙂
I am a bit surprised no one has considered putting a webcam on top of Keilir
It might be the shortest-lived webcam in the history of webcams!
Is there cell coverage on top of Keilir? Unlike the existing webcam sites it’s not close to the coastal road; and it’s similarly far from the airport and any cities. If there’s no signal there they’d have to run kilometers of cable out to the site for the camera to be live, or else build a new cell tower just for volcano watching purposes. Either is likely too expensive.
Starlink is a thing now 🙂
No coverage in Iceland
https://www.starlink.com/map
Says “Iceland: Available Now” and a SpaceX tweet says has been available since February 2023.
I’m pretty sure there is good signal. It’s not exactly remote.
What I gather from all the social media ‘yada yada’ is the excitement in the anticipation of an eruptive event on the order of the level of intensity of a Tina Turner concert performance. I, for one, will be satisfied if the infrastructure remains intact and there are no repeats of the one fool who fortunately outran the lava, another who was seen on the rim of the cone, and the group on a ‘walkabout’ down there. Stupidity abounds among volcano tourists and there is no vaccine for it.
The Rannsóknarstofa í eldfjallafræði og náttúruvá, Háskóli Íslands says in a new post on FB that everything is pointing towards the passage under the area between Fagradalsfjall and Keilis being about to erupt.
https://twitter.com/DottirGongu/status/1677317555193540611
I’d expect the first fissure between Meradalir and Kistufell on the southwestern side of Kistufell. Later an expansion/migration towards the NNE (Litli Hrutur). Kistufell is going to become an island in lava. This map of possible fissures and lava flows shows this possibilty: https://twitter.com/gislio/status/1677308530775281664/photo/2
@RuvEnglish
·
20m
Hjördís Guðmundsdóttir, communications director of Civil Defence, asks people not to travel in the area.
I glance at the web cams from time to time. I keep reading “Beint streymi” as “Bent Stream” fra Fagradalsfjalli.
It must be getting close now, the amount of quakes that are almost at the surface in the past half hour is more than the number of quakes that were only just at 3 km depth a day ago, the quakes are not as strong either anymore on https://vedur.is/skjalftar-og-eldgos/jardskjalftar/reykjanesskagi/ as they were before, still way above background but the trend is pretty clear.
My guess is that the dike is probably within the top couple hundred meters, maybe even 100 meters. It is also not impossible for the eruption to begin behind the webcam based on where the shallow quakes are, which is more or less right under the cam…
Just my luck is it is probably going to erupt when I am asleep like both of the other times… 🙁
The eruption can start as a spectacular blitz eruption with a tall lava fountain and a flash of lava spreading around. There is a lot of pressure with stronger inflow rate than 2022. “The calculations also suggest that magma inflow rate is almost twice as fast compared to the antecedent of the eruption in August 2022, but the total volume of magma which has reached the upper part of the crust is similar, around 12 million cubic metres.”
This means that the eruption may start spectacularly but have a similar total volume as 2022.
Tholeiitid basalt eruptions dont usually start with tall fountains, curtains of fire are rarely over 100 meters. The exception might be the very opening. But in all cases I could find the high fountains are when the eruption focusses to a smaller area and concentrates all the flow into one place. The tallest fountains in tholeiite basalt I have been able to measure so far are those from the southern end of Laki, at just shy of 750 meters.
Alkaline mafic magmas can have much larger fountains. Etna is of course the only appropriate example here. 1700 meters on video 23/2/21 🙂
If a fissure opens it will be obvous but no huge foundry
That’s true. I had in mind the last episode on Kilauea with the lava flash in the first moment. But the double inflow rate compared to 2022 must have an effect. I’m looking forward how it’s going to unfold.
Seismic activity has already been decreasing today. That’ an indicator that magma is rising vertically and the eruption is approaching. This night or tomorrow will be it.
I think the fountain on Kilauea was because the fissure opened at the bottom of the lake and so all of that force had to go through one of the small lowing holes that is usually there. If it opened outside of the lake it probably would have been a curtain of fire maybe similar to the 1970s eruptions.
200 meters though, that is still pretty big, only in 1952 was there a taller breakout fountain, and that was because of gas rich magma. Even then it was not much more.
Relax. I was watching “Bob” like a hawk when someone posted an image of a Drum plot near there as the harmonic tremor set in hard. Personally, I didn’t catch it either. But I was definitely monitoring it for my plots.
Eldey just got yellow.
https://vedur.is/skjalftar-og-eldgos/eldgos/
Interesting, I thought there was something amiss the other day when it started swarming there too.
We have to wait for Fagradalsfjall’s eruption until the “Ghost quakes”, which are wrongly mislocated on Elday, disappear. Then we’ll get a clearer picture about Eldey.
However if Eldey does an eruption like 1989, it will only be a pillow lava eruption at far depth below the ocean’s surface. We may get tremor, but nothing more.
Hmm, aren’t a lot of those ghost quakes normally the individual ones scattered around random co-ordinates though? When you look at these ones near Eldey they seem to form a line that follows the ridge between the island and the mainland a bit like Fagradalsfjall.
Yes, the ghost quakes currently appear randomly all the way from Snaesfjall peninsula to Westman islands. Along Reykjanes peninsula and rift are some quakes on the correct position. The green stars are pretty much correct. But it’s hard to distinguish between ghost quakes of Eldey and ghost quakes of Fagradalsfjall. When Fagradalsfjall begins the fire show, its ghost quakes should disappear and Eldey’s ghost quakes remain for a while.
Eldey is an island rock, sitting on a ridge. An eruption there could break the surface easily. You might see a quite ashy eruption
It depends on how deep the water is where the eruption occurs. The eruption 1989 was around 1km deep: https://volcano.si.edu/volcano.cfm?vn=371022
At this depth eruptions remain pillow lavas. But this was far to the southwest of the Reykjanes Ridge. The currently seismic active part is more in the northeastern, more shallow part of the Ridge. There an eruption can indeed realistically get to the Surtseyan stage.
The 1989 eruption was much further out to sea on the Reykjanes ridge. An eruption near Eldey would be in water that is about 100 meters deep, which os shallower than the seafloor where Surtsey erupted. It might not make an island but will breach the surface, and chances are it will now have intrusions frequently like Fagradalsfjall and so the chance of an eruption there within a couple years s high.
I dont know if Eldey is a slow eruption like the 2021 eruption, or a fast eruption like Krysuvik. The ashy eruptions of the 1200s would lead me to believe the latter though, with those being partly from the end of Reykjanes (Stampahraun) and partly Eldey, which was formed in one of those eruptions.
🙂
Okay. I hope so. One at a time, please.
Reykjanes volcano, smacked in the middle, is like “just leave me alone, guys. I don’t wanna play along”
30EQs in 10 mins, all south of Keilir…
I’ve often wondered that Vatnajökull is completely silent when swarms happen at Fagradalsfjall/Reykjanes peninsula. Is this a data problem or does seismicity indeed decrease on Vatnajökull when Fagradalsfjall increases activity? Is there a negative correlation?
Currently this is occuring again. Vatnajökull very few earthquakes.
Looking at the skjalftar.is plot, aligned e-w, I’m seeing parallel sets of eqs., eg 3 parallel streams of spheres at Eldey. Is this real, or an artifact of the graphic?
Artifact due to coarse quantizatuon of coordinates.
The seismic trace at 01:45 am and 17:45 pm look interesting, almost as if harmonic tremor is trying to get going but not quite. Please see the FAF highpass seismo plot at
. I am hoping soon that we’ll see some comment when the harmonic tremors start.
IMO is not the only agency monitoring earthquakes in Iceland. Check out NASPMON (NAtural Seismicity as a Prospecting and MONitoring tool for geothermal energy extraction).
https://twitter.com/naspmon/status/1677345618904096769?t=8eo5TwdirjzVx-nN8J5pfg&s=19
So, my observation of an easterly trend from Keilir seems to be confirmed by this graphic.
Those are triggered quakes and not magma moving in that direction. At the tip of the dyke there is a very abrupt differential that puts stress in a direction perpendicular to the dyke. This stress triggers quakes on the faults in that direction. If the dyke goes south we would get similar quakes towards Grindavík.
Why nothing to the west? It seems odd that we don’t see a correspondingly set of triggered quakes to the west?
Because it’s actually southeast and not east, so the stress activates faults on the main Reykjanes fault. Same thing with the Nátthagi portion of the 2021 intrusion, which happened south of the main fault. That triggered quakes to the west, because it put stress on the Reykjanes fault to the northwest.
Here’s some material from 2021. Look at the figure showing the 2021 intrusion and two gray areas. Those are the areas where the induced stress meets existing faults and triggers seismicity.
https://www.visir.is/g/20212082627d
Note that this time only the upper portion of the dyke is active, so only the top gray area is affected.
Or from the original source:
https://www.vedur.is/eldfjoll/eldgos-a-reykjanesi/um-reykjanes/
Click the headline
Hvað eru gikkskjálftar?
I am reminded of Gerry Anderson’s “Stingray” and the opening sequence.
“Anything can happen in the next half hour!”
I think this is it.
I mentioned back in 2021 that the first Fragadalsfjall eruption could have been the start of a shield volcano. It didn’t happen, but we may instead see a series of ever increasing eruptions happening at same region and gradually built a shield mountain.
The current dyke has more magma then before. Some people estimate s rate of 88m/s, hence 10x than last time. We may see a 0.5-0.7km3 shield eruption, lasting a year.
My bet is that magma is already within 500 meters of the surface. Hence less quakes. I think this will take 6-24 hours to reach surface. So the eruption will most likely start tomorrow 7th July, probably tremor to start this night!
I think your prediction was right in the end, but it’s still uncertain. The “Fagradalsfjall Fires” which began 2021 may lead to a climactic shield eruption. “Þráinsskjöldur” is a huge shield which has the flat peak between Keilir and Meradalir. There once was a shield eruption which spred lava streams far the north until the ocean. This was one of several shield eruptions. According to the Volcano Catalogue those are typical for Fagradalsfjall. They can be smaller than Þráinsskjöldur, but still impressive.
In my opinion since 2021 we are in a slow build-up phase towards the future shield eruption. The eruptions of the “Fagradalsfjall Fires” evolve over time into this aim.
If I recall correctly, years ago you were one of the first to comment that Rejkjanes should not be ruled out as a spot for one of the next eruptions. You were right. 😉
The comming eruption will be a wonderful sight for the local seabirds having even more cones than humans do as well as filtrering oil drops in each photoreceptor. They also have 4 to 5 color channels that combines with our visual spectrum, so they see not only our red, green and blue but ”non spectral colours” like ”UV – Red” as their brain mixes all the color channels.
So wonder what a volcanic eruption coud look like … some of them have only cones and nothing else, redering them totaly night blind.
Evolved software in their brains may clarify the image as well, by using photoreceptor fast movements and scanning givning them almost as good day eyesight as humans..
The local Corvids are as smart as 7 to 8 year old childern so they will not only see the eruption well, but acually probaly enjoy it mentaly as well If Fagradalshraun erupts again 🙂
The local foxes wont be so lucky in terms of visual experience having just two color channels and red blindness and only 1/6 th of a humans or avarge larger seabirds visual capacity.. the lava will be brown or urine colored for them .. Not red and they wont see it sharply
Hopes the eruption starts soon
So vivid volcanic eruptions is something only we higher primates and diurnal birds can enjoy
For a dog lava lits light brown I think or yellow and they dont resolve a clear 20/20 image having less cones
But a volcanic eruption woud smell strongly for them, much more than for us humans that have de – evolved our sense of smell .. in expense of sight
Degasing in the upper left part of the old lava field on this Camera?
Thats the 2021 lava thats still hot or is it a New eruption fissure ?
Am I seeing people right by the left edge of the old lava field ?
Nowt happening yet. The drumplots still show occasional rock fracturing but no tremor. We’re not in business yet, and (to my mind) not for sometime. There’s been some talk of the depth reaching less than 2km, but the earthquake charts show the average depth is still past 3.5km down. It’s only the unverified / semi-verified events that get close.
I’m not convinced we’re close yet. But things can change very swiftly!
Anything can happen in the next half hour!
Well, there was just a 3.6 at 0.1 kilometers beneath the surface at 99%
Upgraded to a 4.0, still at 0.1km depth!
True, I back the Litli-Hrutur North camera up to that moment of 23:14:08 local time and the camera jiggled as the P-waves hit. 100 meters depth is indeed almost at the surface.
That quake was one of the triggered quakes that happen away from the dyke tip. It’s not an indicator of the current magma depth.
Clive, I agree with you. There is still too many quakes breaking rock at depth around 5 km to assume that magma is ready to pop out on the surface. There has been an overall trend of quieting, I think we all agree on that. But as to a surface eruption or a dike emplacement which fails to breach the surface is still up in the air.
Am I seeing things tht aren’t there? Right side, under the third hill from the right, somewhat bright spot at the base of the hill…
https://www.youtube.com/live/uZGleOgreBY?feature=share
Now that the Reykjanes is on the verge of a new eruption…has there been any signs of ground heating from below?
There’s a YouTuber by the name of Just Icelandic who has gotten his hands on a drone capable of sensing heat on the surface. I won’t be able to post any YouTube links easily – not easy to do that on my cell (I’m not home bc I’m out drinking a few G&Ts and Molson Canadians!).
Only problem is that it’s been sunny enough to cause the ground to heat up from the solar radiation alone -this makes it harder for him to detect heat coming from the magma underneath.
This would work so much better if the infrared camera was capable of detecting infrared in the lower frequency regime of the infrared, not in the near infra-red region. But I am not sure that a bolimeter for such is affordable for the average person. I quickly pulled up typical bolometers, just to check. What is needed is around a 100 micrometer bolometer in order to truly detect subsurface heating. Perhaps some experts in bolometers can offer more information?
Another thing I forgot to mention is that it’s going to still be light 24/7 even if the sun dips below the horizon for a bit. After all, you have to keep in mind that most of Iceland is just below the Arctic Circle! It won’t matter if it starts erupting even at 2-3 am as opposed to middle of the day.
The Iceland quake at 2023-July-07 at 23:14:08 Iceland time has a beach ball determination of 264 deg strike, 73 deg dip, and 3 deg slip/rake (magnitude 4.01) but I want to argue that the actual movement is 84 deg towards the east from compression on the dike near Keilir. The dip of 73 degs is a fairly vertical fault line slightly offset from pure vertical 90 degs. 3 degs rake would indicate that the east side moved up slightly. I would argue that this might be the best understanding of this significant quake. IRIS has a quick video explaining beach balls, see https://www.iris.edu/hq/inclass/animation/focal_mechanisms_explained
I welcome comment from any geologist who knows this material inside out.
It’s a triggered fault away from the dyke. Those are usually N-S striking. If you look closely at the InSAR interferogram picture you can actually see the faults from a couple of similar quakes, just to the east of the intrusion.
It’s like bookshelf faulting. The general left lateral E-W deformation is taken up by right lateral N-S striking faults.
Look at the top fringes of the right “wing” of the bufferfly pattern. They are broken by intersecting lines. Those are all M4+ triggered quakes that happened between the two satellite passes.
https://www.vedur.is/um-vi/frettir/bigimg/4430?ListID=0
Tomas, I appreciate your replies. Thank you.
Would this thing just erupt already? I am getting bored! I have patience for CCN, Trident, and other felsic system but not a volcano like this.
You could watch Katla to make sure she does not sneak in an eruption while we are all watching Fagradalsfjall. She can do more felsic lavas. 😉
Christobal (Nicaragua) had an impressive explosive eruption with Pyroclastic Clouds two days ago: https://www.volcanodiscovery.com/san-cristobal/news.html
Is Carl there around?
Or there is Ubinas in Peru …
https://english.elpais.com/international/2023-07-06/peru-declares-state-of-emergency-over-ubinas-volcano-after-17-blasts-and-170-quakes-in-two-days.html
Not watched this cam so early in the morning before. Is this new steam from the lava or has it been around a while from the 2021/2022 eruptions? (Bear in mind that the air in Iceland would be cooler right now so “steam” from last years and before activity would show more at the moment).
Source: https://www.mbl.is/frettir/innlent/2023/07/06/fylgstu_med_skjalftasvaedinu_i_beinni/
There is a video on YouTube titled *Volcano Watch 2023: Waiting On An Eruption.*
Being an old lady I am not good with inserting links but it is worth watching for 2 reasons,
First, during the video you can see the old eruption from 2022 and in the background you will see that the edge of the lava is still steaming even during the day time and would me more noticable during the night.
Second you get a good view of the area we are watching.
As a bonus right at the end you see the reporter actually bending her knees and the camera shake as a quake struck.
Now the earthquake numbers and strength have decreased. That’s a sign that we’re getting closer to the eruption. But the vertical way of magma from aprox. 800m deep to surface is long.
I’d expect that we see a sign of gas/steam at the most a few minutes before the eruption. Not more and not earlier.
what is the best web camera to see this degassing?
There isnt any degassing, maybe some steaming on the existing lava fields. Last year the only sign of the eruption before lava broke the surface was some white fume that was a few seconds earlier, followed by more dense and slightly dirty clouds that might have been from the dirt on the hillside being blown out. Lava probably breached the surface at this time but was only clearly visible a few minutes later. But that was last year whic hwas i na valley, this eruption is probably going to begin on an open plain so the wind will probably be a lot stronger and the lav probably visible as soon as it is out of the ground.
But we are talking literally seconds between it lookign exactly normal as it has for the past 10 milleennia, to there beign a very obvious spattering fissure. No degassing or moss fires, maybe at the ends of the fissure where the dike is shallow but didnt surface, but it is very unlikely that the dike would get to the surface close enough to ignite the moss and fume but not actually erupt lava. That has happened, but usually some other part of the intrusion erupts to remove the pressure, an entire dike reaching the surface without any lava flowing from the crack at all I believe has not happened in any major way.
The eruption will be very obvious when it starts 🙂
Thank you for confirm that it is the older stuff steaming.
I have been looking into the Eldey swarm. Here is a view of all located earthquakes in Reykjanes for the past 2 days:
Eldey and Fagradalsfjall appear as similarly shaped SW-NE trending swarms, which matches with the direction of dike intrusions. Eldey is more faint, but that is partly because only larger earthquakes are located there, being away from the coast of the island and the seismometer network. The Eldey swarm builds up gradually, it starts around 12-13:30 Iceland time on Thursday with an initial pulse of earthquakes, then goes into a 3 hour hiatus and starts to gradually build up again. This is similar to what happened at Fagradalsfjall where there were a series of small swarms separated by quiet intervals, first at Thorbjorn, and then at Faradalsfjall. The peak of Eldey activity is from 0 to 5 Iceland time, on Friday, when the number of earthquakes reached up to 47/hour and most of the largest quakes happened. There were a total of 7 earthquakes M 4 or larger, all in a 23:29-5:07 interval.
This looks a lot like a dike intrusion. But the most conclusive evidence is that there is a spatial progression of earthquakes in time. Earthquakes from 1:56 to 23:30 on Thursday are shown in yellow. Earthquakes from 23:30 on Thursday, to 00:15 on Friday, are orange. And finally, the red earthquakes are 0:15-2:34 on Friday. The rest is not included because it doesn’t show any further advance. The swarm seems to have started near the summit of Eldey and gradually shifted NE, highly consistent with a NE-propagating dike intrusion, very similar to Fagradalsfjall.
So it might be the first time in recorded history where simultaneous dike intrusions occur at volcanic systems 40 km apart from each other.
So it might be the first time in recorded history where simultaneous dike intrusions occur at volcanic systems 40 km apart from each other.
Should I add, without a M 7+ earthquake causing it.
An important question is: How deep is the possible eruption site below the level for Surtseyan activity? How much has a volcano there to rise to change from effusive pillow lava to explosive submarine eruption style?
Remember El Hierro 2011? This was Europe’s last Surtseyan eruption. Something like this may be a realistic scenario for Eldey. A submarine eruption that sends bombs and Lapilli to the surface, but the cone stays in Neptun’s realm. El Hierro had no visible steam or ash plume above the water.
El Hierro is not in Europe. The entire Canary Islands lie on the African Plate.
Most of the earthquakes in recent hours have been between Keilir and Krysuvik, not on the dike like before. I dont know if this means the dike has extended east at an angle or if it is just a tectonic trend but the dike seems fully formed in the area the eruption is predicted. RUV have said the magma is less than 1 km underground now, and the supply rate to the dike is significant, much more than last year or 2021, although without a given number.
Eldey seems to be quiet now too.
It is always hard to predict anything but the trend of decreasing seismicity would suggest the diek is probably going to surface in the next day. I guess it just has to fill in all the cracks first, it is a rift zone so there are probably buried faults below Thrainsskjaldurhraun. The webcams are also directly over the dike, so it is not out of the question that the eruption begins behind it out of view, or even under it which would be quite the sight.
The earthquakes around Keilir are around 5 km deep. They are caused by the stress field from the new dike but are not directly related to growth of the dike, I think. Keilir is a big mass and will be an obstacle to the dike: it can’t grow underneath it because of the weight above. So the dike stopped. It now tries to push its way up, everywhere along the dike. Once (if) the dike finds a weak spot, it bulges up, the pressure there goes up because the force pushes on a smaller area, and a rift forms above. The final step can be fast.
I repeat: those are triggered quakes. I dropped a link in my last comment to an IMO page explaining it.
I’m starting to feel like a parrot repeating myself 😂
Some serious shaking on the Litli-Hrutur cams in the last few minutes; I seldom attempt to predict eruptions but I think we could be getting close here!
The centre of the dike is between Litli-Hrútur and Litli-Keilir
Source: https://en.vedur.is/about-imo/news/earthquake-activity-in-fagradalsfjall-area
http://hraun.vedur.is/ja/drumplot/allarsort.php
This drumplot is showing a LOT of shaking currently.
Sorry, I should have said to scroll down to the faf plot
Don’t underestimate the Icelandic weather! 😉 The Atlantic oceans sends much wind to shake the cams. That’s esily confused with earthquake shaking.
But if we see rock falls happening, then it must be a true sign of an earthquake. IMO warns that Rockfalls are possible on the whole Reykjanes Peninsula due to the earthquakes.
Agree that camera shaking is usually from the wind, but in this case (and in several other cases the past couple of days), the shaking has clearly been correlated with nearby and/or strong quakes.
The plot is thickening. That is, the tremor plot at http hraun.vedur.is/ja/drumplot/drumplot/fag_highpass_2.0.png. (note, http, note https, in case your browser automatically inserts the wrong one). There is weak but notable higher noise since the last 20 minutes or so. Could easily stop again though
Albert, I think we’re looking at a different volcano here. See http://hraun.vedur.is/ja/skjalftar/silstn.html which gives the station map. FAG is located clear over to the west, not far from Öræfajökull. You might have discovered something going on here.
That is funny. There are indeed two stations called fag and faf, bother abbreviating names starting with Fag.. Easy to get confused.
The most likely eruption site is be between Litli-Keilis and Litli-Hrútur. Inflation there has decreased, and they judge this as a sign that magma is close to surface. We only have to wait whether it breaks through or not, said Lovísa Mjöll Guðmundsdóttir from IMO.
https://www.ruv.is/frettir/innlent/2023-07-08-kvikan-verulega-naerri-yfirbordi-387298
Litli Keilis (or Little Keilir) is to the west/left of Keilir, if we look the the Northern cam: https://www.youtube.com/watch?v=yJfiMhqLgTY
So somewhere between the Camera and the small hill is the proposed eruption site.
All the flat land visible in the Webcams is the shield volcano. If the Big shield eruption repeats, all the land from Litli Hrutur to the sea on the horizon will turn into the hell of a shield volcano.
This was in response to B. Bound request.
Thanks so much for the map Albert. I was looking without success this morning for a map with the names on.
I find this one useful. You need to zoom far in to see all the names
https://kortasja.lmi.is/mapview/?application=kortasja
That seems rather unlikely. The early post-ice-age era had much larger eruptions than the period since