Greip, Gjálp’s Mysterious Sister

In this article, we move away from the usual suspects in Icelandic volcanism and turn our attention to a feature many of us have noticed over the years. This feature has only been revealed from seismicity, but here I try to unravel the past and future activity as well as give this feature a sense of belonging, in a fissure swarm sense of the word…

Mythology and Name

In Norse mythology, there were two tempestuous giantesses, Gjálp and her sister Greip. They were the daughters of Geirröd, a giant who really didn’t like Thor… maybe it was hammer envy? Surprise surprise, Loki was involved as well, up to his usual tricks of winding people up and leaving joke-shop items lying around no doubt. So, Geirröd wanted Thor dead and so hatched a plan to lure him to his demise. On Thor’s way to Geirröd’s castle, Gjálp tried to help her father out by flooding the river Virmur as he crossed. This didn’t go well for Gjálp who ended up with a large boulder tossed at her from a damp and moody Thor. Once at Geirröd’s castle, an incident with a booby-trapped chair backfires, literally, on Geirröd and Thor ends up falling through the floor. The mass of Thor’s armour-clad beefcake body combined with gravity induced velocity results in the breaking of both Gjálp’s and Greip’s backs. This then escalated into a bit of a Kill Bill moment, complete with Norse ‘alarm’ music and a heavy dose of artistic license from myself, and Thor ends up killing them all. Probably brutally, with a red hot iron bolt involved… They should probably make a film out of that.

On to the name. The IMO had already assigned the name Gjálp to the 1996 eruption between Grímsvötn and Bárdarbunga, for sound reasons. The eruption melted 3km3 of ice and the resulting meltwater flowed via a narrow channel into Grímsvötn’s subglacial lake which then later escaped as an impressive jökulhlaup. Whether Thor was crossing the river Skeidará at the time has yet to be confirmed, but it certainly took out the bridge there.

We now arrive, logically, at the name Greip as put forward by Andrej during an evening of back-channel discussions. But what/where is Greip? I hear you cry! Well, it’s a volcanic feature that has been mentioned on the blog over the last year or so as another name. That name is ‘Unknownabunga’, however, the -bunga suffix is misleading in this case as there is no ‘bulge’, but it was useful as a stop-gap name whilst we consulted with the Norse gods.


Some of you may already know the location of this feature and have been drawn to the earthquakes that have happened in this area over recent years. This area was probably best revealed during the August 2014 eruption of Bárdarbunga. During the eruption, the dike that travelled out of Bárdarbunga along a radial fault in an SE direction suddenly turned NE creating a distinctive elbow shape in the dike path. It has been proposed that magmatic pressure within the Greip area was higher than the magma in the migrating dike and so deflected the dike along a lateral fault at the SE edge of Bárdarbunga’s fissure swarm.

Location of Greip on the VC map with nearby features labelled for reference. It is implied that Greip is an extension of the Grímsvötn fissure swarm in this image. Image: Beardy Gaz, Data: IMO, FutureVolc, et al. Base Map: Google Maps.

There could be alternative reasons for this deflection though, one of which could be that this was the optimal line of least resistance after the dike travelled along the radial fault. This lateral line of weakness could have been a pre-existing fault or graben that was hidden from view under many hundreds of meters of ice. This deflection may have happened regardless of the magmatic pressure in both systems. But if we base our hypothesis of the deflected dike path on higher magmatic pressure from Greip, what could the potential different outcome have been with lower magnetic pressure in this system? Maybe the dike would have entered Greip instead of the lateral fault and we could have seen a rather more different eruption spectacle. We’ll never fully know the list the variables and potential outcomes during these volcanic events, but aren’t chaotic systems fascinating!

Another assumption I have made is the parental system. In this case an extension of the Grímsvötn fissure swarm. I’ve made this assumption purely on the orientation of the fissure swarms in this area and the fact that the ‘official’ fissure swarm, as implied by FutureVolc et al, sits right next door to Greip, to the SW. Another theory is that this is an extension of the Bárdarbunga fissure swarm along a similar trend to the line of the 2014 eruption radial fault. I will return to this later when we look at the topography of the area.There is also potential that Greip is a completely separate entity and may not belong to any identified fissure swarm or central volcano with its own unique magmatic signature. With no known eruptions and no rock samples to perform a petrological analysis on the origins and family history of this feature remain a mystery. I will return to petrology later in the article.


We know the activity of the dike during the 2014 Bárdarbunga eruption highlighted Greip on the map, literally, but what evidence is there of previous activity? Prior to 2004, there was little detectable earthquake data available, I found only one reference to a Greip earthquake in the period 1975-1985 and a handful of ones between 1995-2004. We know that the sensitivity of the seismic network has increased 10-100-1000 fold over the recent years and this area is no exception. Positioned in the middle of the Vatnajökull ice cap, and with no protruding bedrock, detection of earthquakes in this area relies on the sensitivity of the surrounding seismometers at Grímsvötn, Bárdarbunga and Kverkfjöll, as an example of three, to triangulate the location, magnitude and depth.

An aerial view graphic map showing 2004-2017 earthquakes over the northern part of Vatnajökull. The main central volcanoes are outlined. Greip can be seen to the SE of the elbow in 2014 dike. Map: Andrej Flis, Data: IMO.

From this relatively short period of time, we do have a good picture of what’s hiding under the ice other than ‘The Thing’ and a crashed spaceship. The map is saturated with shallow earthquakes, especially from the dropping of Bárdarbunga’s caldera and the dike path during 2014-2015. Hydrothermal activity shows up in the top few kilometres of crust and this can be seen along the Hamarinn-Loki-Fögrufjöll system(s) and Kverkfjöll. Activity around Grímsvötn is from the eruptions in 2004 and 2011 and the build up to the next eruption. The activity at Greip is predominantly between 15-25km deep indicating that magma is the culprit here but has little surface manifestation.

If we look at the depth profile of Greip from the south with all earthquakes plotted we see a column of earthquakes from ~25km deep all the way to the surface. However, this is not a clear picture of the system and it highlights the importance of having alternative views, models and different measurements to build up an accurate picture of what has and could be happening.

Depth plot of all 2000 – 2017 earthquakes in the Greip area looking from the South. Plot: Andrew Flis, Data: IMO.

So if this isn’t a single column then what is it? It’s actually two separate events that look like one entity on this view. The bottom half, below 15km, is predominantly Greip whilst the top half is predominately the 2014+ dike activity. This becomes clear if we take a south-westerly view of the area.

Depth plot of all 2000 – 2017 earthquakes in the Greip area looking from the SW. Plot: Andrew Flis, Data: IMO.

We now see the that the single column as seen from the south is detached around 15km deep with dike activity sitting to the north of Greip and this correlates with the aerial presentation of the data. Greip proper consists of, dare I say it again, a wedge of earthquake activity between 25-15km depth. Andrej refers to this as a dike swarm, pictured as a branching lightning bolt discharge, and his description has merit when it comes to visualising what’s happening deep in the crust. In this case, the branching matrix is made up of multiple dikes throughout the crust. There’s no evidence of any magma chamber or conduit from the seismic data and the best way to describe this, from my point of view, is a proto-chamber/reservoir of magma, almost like a honeycomb/sponge filled with water, but not as densely intruded with magma like the mature chambers we’re familiar with at the main central volcanoes. This could be a very young feature we are starting to see and something that may have happened at the other volcanoes during their gestation. There appears to be a ceiling around 15km which contains the majority of the dike swarm below this level. The overlying rock strata may be harder in this area and therefore less susceptible to failure {cue imaginary PHD research montage}.

Static graphics are extremely useful for displaying data, but we are still limited in the clarity of the presentation in two dimensions. If we bring time into the equation then we get a fantastic visualisation tool of cumulative activity year by year and how activity in one area affects other areas and even the cascade of earthquakes along multiple lines of weakness.

Cumulative depth plot of all 2003 – 2017 earthquakes in the Greip area looking from the East. Plot: Andrew Flis, Data: IMO.

At the start of the cumulative time sequence, we do actually build a picture up of a single column with earthquakes at all depths. Although the main Greip activity is below 15km, from magma influx and therefore increasing pressure, it will have corresponding upper crustal earthquakes associated with stress changes from doming of the area as well as seasonal earthquakes related to ice loading from changes in mass of the overlying glacier.

In 2014, and subsequent years, you can see the dike earthquakes propagate in the upper right of the plot which quickly fills this area. At the same time, there is an increase in the number of earthquakes at Greip proper. The effect of the dike passing by may have weakened the surrounding crust allowing for more rock fracturing and magma influx. However, during this period many smaller earthquakes were recorded in both areas and this increase in quakes at Greip proper may be related to increased sensitivity and the resulting higher resolution of the network during the 2014 eruption. As we are dealing with such a ‘new’ process, from a human observed timescale and viewpoint, we can’t be sure of all the cause and effect processes and the nature of the beast. We would need many years of data from this area to build up a clearer image of what Greip is up to.

Topography and Anomalies

So we finally get to the topography of the area and here’s where the assumptions and possibilities of the area really start flying around like deranged monkeys on an evil mission. Although this original map was created in 1988 and the resolution is not as high as it would be if conducted today, it does help in probing the depths and trying to work out what’s going on at Greip.

Topography map from radio-echo soundings with an overlay showing the location of the main volcanic features in relation to the underlying topography of northern Vatnajökull. Overlay: Beardy Gaz. Base map: Björnsson 1988.

We’ll start with the Grímsvötn area first and work our way round. Although the base map was produced before the Gjálp eruption in 1996 a small ridge can be seen extending to the north of Grímsvötn around the overlay marker for Gjálp. It appears this area has been active before in the past and this ridge may well have been formed from multiple radial eruptions from Grímsvötn creating a hyaloclastite ridge. To the NW we have the Loki-Fögrufjöll ridge and its connection to the Hamarinn system. A link between Bárdarbunga and Hamarinn could be inferred purely from topography, but the existence of Hamarinn as a separate central volcano, rather than part of Bárdarbunga’s fissure swarm, is still hotly debated. To the South, we see the connection to Háabunga, again another area of debate that I’ll leave for another day. To the East, we see a complicated series of ridges and domes that appear to intertwine with the ridges from the Kverkfjöll system. Maybe a connection existed here many millennia ago when Kverkfjöll had its day sitting on the plume head barking ash and lava at the sky. Finally, we come to the NE. A ridge extends out from NE Grímsvötn, but turns to the NNW and appears to intermingle with a ridge coming from the SW of Bárdarbunga. As Gjálp showed us, the large magnitude 5 non-double-couple earthquake in Bárdarbunga caused all manner of magma shenanigans under the area which has been implicated in kicking off the Gjálp eruption from Grímsvötn. Multiple past and future interactions between these two monsters cannot be ruled out and hopefully, we’ll see more in the near future which will further our understanding of large volcanic system interaction.

So what about Greip? Well, this area sits to the NW of this Grímsvötn-Bárdarbunga ‘handshake’ and doesn’t seem to have a pre-existing ridge associated with it from Grímsvötn nor does it seem to have any existing eruptive surface deposit visible with this data. Greip seems to have more in common with the ridges extending from the SW of Bárdarbunga than Grímsvötn. Another thing that caught my eye was a series of ridges extending to the NW from Greip that run between, and in parallel to, the 2014 dike path and Kverkfjöll. This might have been the site of previous lateral dike eruptions from Bárdarbunga and may link up to the graben that exists out in Holuhraun. From this evidence, the parental system could be implied as Bárdarbunga and a re-drawing of the fissure swarm outlines may need to be done if more evidence comes to light.

Looking at the anomaly data, the older established intrusive bodies can be clearly seen around the big central volcanoes. There is some nice correlation between these dense intrusive bodies and the bedrock topography. Again, some limited interconnection between the central volcanoes could be implied by this data at some point during their birth and subsequent evolution. But poor young Greip is sat all alone in the big blue…

Map showing the magnitude of the horizontal gradient of the Bouguer anomaly with the VC map overlay. Overlay: Beardy Gaz, Map: Gudmundsson 2007

There doesn’t appear to be any intrusive bodies underlying Greip so past intrusions must either have been minor or the intrusions are still hot and therefore less dense. Negative anomalies can indicate areas of fresh hot magma, this can be seen within the caldera complex of Grímsvötn and Bárdarbunga. Vonarskard and Kverkfjöll still have negative anomalies and may indicate that magma is still is present even in these post-caldera and less active systems. Kverkfjöll still has hydrothermal activity and the occasional phreatic explosion like that in 2013 (GVP) and this fits nicely with the implied underlying magma body. Greip sits within a large negative anomaly, but this is not to say that there is a large magma body ready to destroy us all like the media likes to portray at Yellowpebble. It could simply indicate an area of lower density rocks, like hyaloclastite, which have a lower density than gabbro and other dense intrusive rocks. The negative anomaly may also indicate this area is hotter, and therefore less dense, than the average background crust of the greater area. This area does sit above the proposed mantle plume head and this additional heat may lower the density of the rock over a large area.


We now return to the petrology of the known eruptions in the greater area surrounding Greip. The Gjálp eruption was initially pinned to Bárdarbunga due to the aforementioned magnitude 5.6 non-double-couple earthquake (more here) and large scale magma movement and then pinned to Grímsvötn from local seismic data. It was in fact found to be a completely separate system, with the bulk of the ash identified as basaltic icelandite. Icelandite is an iron-rich volcanic rock between rhyodacite and tholeiitic basalt as it contains more silica than basalt. We have the great geologist Carmichael to thank for identifying icelandite from his work at Thingmuli (nothing to do with ‘The Thing’, thankfully). However, with further microprobe analysis, it was revealed to be heterogeneous, with compositions ranging from Grimsvötn-like tholeiite to icelandite, an intermediate magma between the olivine tholeiites of Bárdarbunga and Grimsvötn. Crustal melting has been implicated in this change from theolitic basalt, common from the plume/rift volcanoes, and the resulting increase in the silica content. Gjálp truly was a mix of parental magma from Grimsvötn with a little bit of its own concoction to make it an individual in its own right.

As we have no evidence from Greip of past eruptions we have nothing to base its magma composition on. All we can do is rest uneasily on raw theory and extrapolate data from the surrounding volcanoes and intermediate eruptions between them. It’s possible that if Greip were to erupt it would have a composition closely resembling theolitic basalt from Grimsvötn and Bárdarbunga, depending on who initiated or contributed to the eruption. Crustal melting may contribute to its own individual petrology, and may be higher or lower than Gjálp due to the length of time the magma has been accumulating in this proto-reservoir and how much crust it melts on its way to the surface. Of course, if it has it’s own unique deep source of magma from the mantle it will have its own individual signature regardless of crustal melting.

The Future?

After experiencing the recent ‘slaps-in-the-face-with-a-wet-fish’ results of Brexit and Trump in regards to poll predictions and the actual outcomes, I’m hesitant to predict which way this one will go. Of course, nature is far more complex than deciding between say glacial exit, glexit, or remaining in restless slumber beneath a frozen sky.

Aerial map of North Vatnajökull showing recent earthquakes in the last 18 months. Map: Andrej Flis, Data: IMO.

The graphic above shows earthquake data from the previous 18 months. The 2014 dike can clearly be seen popping and contracting away as the magma slowly cools and the surrounding crust shifts and adjusts to the rather rude intrusion. Bárdarbunga is still noisy post-eruption with the ring fault clearly seen as well as the deeper activity to the NW. The line of quakes indicating the Hamarinn-Loki-Fögrufjöll systems can be seen as it ‘points’ towards the Gjálp eruption area to the North of Grímsvötn. Greip can be clearly seen as the cluster of deep to mid-crustal depth earthquakes all alone to the SW of Bárdarbunga. Activity appears to be increasing in this area as we’ve already had numerous earthquakes in just 18 months. A word of caution though, as I’ve stated previously, this could be purely down to increases in the sensitivity of the network.

So, what if we are seeing an increase in earthquakes, where’s all this recent activity heading? Should we all be pulling up a chair and putting the popcorn on in anticipation for an eruption? Should the Daily Fail crank up their Mislead-o-MaticTM headline generator? Hopefully, not ever on the latter point. We need to rely on actual data rather than sensationalism from the media. So let’s look at where the data is heading.

Up to date cumulative energy graph for the Greip area 2005-June 2017. Graph: Andrej Flis, Data: IMO.

Again, with the limited date range and seismic network sensitivity variables thrown into the mix, a true picture of trends becomes hard to formulate. We don’t have the seismic data between eruptions that we have for Hekla and Grímsvötn so we don’t know the rough failure point measured in cumulative energy release. There is an increase in quantity in the last few years, but the magnitude and therefore cumulative seismic energy isn’t increasing exponentially as would be seen during a run-up to an eruption. Again, we may have to wait a few more years before we can start to see any clear trends, but every volcano has to start somewhere…

And so this brings us almost up to date. Last month there was a triplet of earthquakes at Greip as seen from the IMO data:

19.06.2017 17:24:26 64.590 -17.180 17.0 km 0.9 99.0 17.4 km ESE of Bárðarbunga
19.06.2017 17:23:27 64.584 -17.179 15.1 km 1.1 99.0 17.7 km ESE of Bárðarbunga
19.06.2017 17:22:36 64.587 -17.170 18.2 km 2.2 99.0 18.0 km ESE of Bárðarbunga

At this depth, it’s likely this was caused by a small dike intrusion penetrating upwards. Another offspring in the large family of dike swarms at Greip. As magmatic pressure increases from depth, possibly from the plume head exerting increasing pressure as we head into a new Icelandic peak cycle, we could see increasing amounts of multiple earthquakes and maybe the odd swarm. As we’ve seen from the previous data, there could be a relatively stable and resistant crust acting as a ceiling, helping keep any intrusions small and at depth. If this is the case then this could potentially keep a cap on things for many years to come, sadly for the impatient volcaholic. However, we’ve no way of knowing what the critical failure point is in this system. A large intrusion at depth could destabilise the entire proto-chamber/reservoir and lead to the birth of a truly fascinating and wondrous thing. The birth of a new volcano in the land of giants.

Beardy Gaz


(Gudmundsson 2007)

(Björnsson 1988)

Friday Riddles

The Friday riddles have returned and can be found in the Friday posts for now, but we will look into opening the Sheepy Bar in due course. Once open, grab a beer (or drink of preference) and feel free to discuss anything you like in there as well as answer the riddles. We want to bring the community feel back to the blog and what better way to do that than having a drink and putting the world to rights!

If you’re unfamiliar with the volcanic riddles, simply deduce which volcano the clues hint at and leave your answers in the comments. Expect a ‘Ding!’ for every correct one :-):

  1. Doctors Cumbrian watery abode. – Mount Carlisle, answered by Daisaster
  2. Hot electric tunnel of love. – Gunung Kelud (Ampera Tunnel) answered by Bjarki
  3. Towering depressed volcano for all to see. – Eifel Volcanic Field, answered by Thomas A
  4. The man, the car, the movie. (Antropomorphic nickname) – Herbert Island, (The Movie Herbie) answered by Daisaster
  5. The pastoralist cowbell of: Ngorongoro (Ngoro is a massai cowbell) answered by KarenZ

In Other News…

As part of the increase in the community feel on the blog we want to put forward a few ideas. One of these is having an ‘open-conduit blog night’ in which anyone can submit a poem, a nugget of knowledge/experience or an essay on volcanoes and geology in general. I haven’t worked out the logistics yet as I’ve been too busy writing this article and moving house, etc., but if you have any suggestions for implementing this kind of functionality, or direct me towards some decent WordPress plugins, then please let me know. We also hope to integrate the Facebook group’s posts and comments on the blog and as part of this, you may notice design changes to accommodate the additional content, i.e. wide-screen content. Again, if you have any suggestions, please let me know.

And lastly… we are always on the lookout for writers for the blog. It doesn’t matter what your experience or knowledge level is if you can write an article on volcanoes, a particularly intriguing aspect of them, something within the greater geology context or even a topic within the broad scope of historical evidence of past events on Earth or beyond then please get in touch! In addition, any coding or graphical skills are always welcome and help us to further our understanding of these systems, disseminating the information to our readers and hopefully kick-starting a research venture to test the various hypotheses put forward.

133 thoughts on “Greip, Gjálp’s Mysterious Sister

  1. Great article.
    That being said, even with artistic license being used, I’d be mighty miffed if Thor killed anyone with the hammer in a depiction of this tale, as he doesn’t bring it at all on the trip to Geirröd. Geirröd is killed when he flings an red hot iron bolt at Thor (which he grabs from the roaring fire), Thor catches it with his irongloves and hurls it back, throwing it through and shattering the iron pillar Geirröd’s hiding behind, and through Geirröd himself, only for it to fly way out into the horizon.
    Depending on interpretation, this is how humans got hold of iron and learnt that when it was red hot it could be worked into whatever object they desired.

    • Thanks for the clarification Bjarki 🙂 I only took snippets of the story from Wikipedia so a lot of details were missed of the actual battle. I’ll update it when I get chance.

  2. And, for those of you able to view it, a pretty decent video about geologic processes. If you pay attention past the hype on gold, you will see a good description of mineralization processes.

    Side note: The video makes a statement about gold forming in space from supernova explosions. This is because nuclear fusion (which is the poser that drives stars) ceases to produce excess energy after the formation of iron. To fuse anything higher than iron on the periodic table uses more energy than it yields.

  3. Very nice post! The negative anomaly could be explained by molten crust. Magma from the mantle would be denser.

    I can feel riddle head aches coming along.

  4. Let me hazard a guess at riddle number 1: Borrowdale in Cumbria. The are is host to the Borrowdale volcanic group.

  5. Btw, have you guys asked IMO (and other relevant authorites) about the potential option of having Greip as the official name of the volcanothingy, and not just as a name used on this site?

    • I hadn’t thought about it to be honest, especially as it’s only an embryonic volcanic feature at present. I’ll see what the Norse Gods think.

      • The Canaries weren’t too keen on the “Bob” idea, they prefered some legendary local Carp or something.

        • Would be awesome with a volcano named Bob, “Bob is erupting!” “Bob has laid waste to everything in the path” “SHAME ON BOB!!”

        • Death by mullet… Are we talking about the hair style or the estuary fish though? Two very different death scenes involved…

          • The Mullet Hairstyle.:
            When I lived in Coos Bay, Oregon , you weren’t considered cool unless you wore a Mullet and a nose ring (male or female-Females were allowed a ring/jewel in the cheek at the top
            of the jeans -right below the Tattoo
            at the base of the back.
            (the tattoo was also known as the “skank
            bar code.)
            Glad I’m back among the Big things;
            Trees, Rocks, Mountains…

          • ‘Skank bar code’, it’s amazing how the same thing has so many different names. It was often referred to as ‘arse antlers’ in the ‘Shire.

      • Thanks for this good article! I also think, Greip is a great name for unkownabunga!

  6. On several maps you’ve drawn the Holuhraun dyke in green. You show a segment leaving the edge of Bárðarbunga caldera, traveling towards Greip – and then turning through almost 90 degrees and heading out northeast, trending in the general direction of Askja.

    Now look at your second illustration – the IMO cumulative seismicity 2004-2017.

    There is NO seismic evidence for the existence of that first segment of the dyke whatsoever. Nothing. There has been no significant seismicity along the line of that first green dyke segment before the near right-angle turn any time during those all those years or in the immediate run-up to the eruption.

    So what exactly is the evidence for its existence? What data – exactly – permits you to draw that first part of the green line?

    Oh sure we could conjecture that perhaps the dyke ‘must have’ originated towards the Bárðarbunga caldera but rock in that area is too hot and ductile for any seismicity and the initial advance of the dyke was ‘silent’ for that reason but still that’s poor science; absence of evidence is no evidence of existence. I’ve asked about – and thought myself about – that seismic dead (relatively) zone before but never been able to arrive at a satisfactory answer.

    • The initial part of the dyke was indeed there, it was though far less numerous in earthquakes and is fairly drowned out by later earthquakes. But during the two days it evolved it was quite obvious, at the “knee” the number of earthquakes exploded so it looks like there was no first part of the dyke, but it was indeed there.
      The reasons for it being far less “noisy” is quite probably quite obvious. The most likely explanation is that it remained as a semi-open conduit since the last eruption at the original “Houlhraun”, remember that the last one is correctly called “Nornahraun”.
      It is also good to remember that the sides of Bárdarbunga is well known to be severely weakened and fractured as evidenced by the multitude of fissure eruptions in the past.

      I am amazed that you are suggesting that the dyke did not originate at Bárdarbunga, after all the caldera drop is a fair piece of evidence for you to explain away.

      • Alas, against scientist and public recommendations the municipal government, in whose lands Nornahraun was formed, opted to officially name the new lava field Holuhraun because “reasons”

        • Huh, they berated me in emaily form for always calling it Holuhráun instead of their preferred form of Nornahraun… And after that they went and copied me. Life is wonderful…

          • Yeah, a lot of people weren’t too happy… Probably why the hobbies hillbillies waited until October 2015 to make a decision. Personally I like all the other official suggestions better (from worst to best: Flæðuhraun, and by a wide margin Dyngjuhraun, og Nornahraun

  7. Great to see the Friday riddles back! I apologise in advance for any ‘just gotten back from the pub’ type answers 😉 Perhaps we will see some old friends back to play, I do hope so.

    I like to call the elbow the ‘Great Tick’. Looking at the IMO maps it sometimes feels Bardy is giving itself a good ole pat on the back … Right again! Well done Sir, have another tick 😀

    • Yay – the riddles! I’m doomed. I can never get those!

      For the Great Tick, back on 25 May 2016 I proffered:
      “How about hnakkurliðolnbogi = saddlepoint elbow (Giggle translate, of course).” after Cbus05′ Olnbogi suggestion.
      I thought the Daily Fail journos would struggle with that one…

      Icelandic for the Great Tick is “Frábær merkið” according to Giggle Translate.

      Sadly this does not answer the riddles….

      • Haha, hnakkurliðolnbogi truly looks like a mouthful to me … or rather I imaging it to be the sound made when coughing up a lung-full (no offence intended for the lovely people of Iceland or their beautiful language). Keep trying, one day it will be the answer to a riddle! 🙂

  8. and a guess on riddle 3

    Ka’eleku cave, also known as the Hana lava tube

  9. Number 5 is Turkana (well, one of the volcanoes around the lake).

    • And I think number 3 is the Red Mountain cinder cone of the San Francisco Field. I’m completely stumped for the others!

    • Modern society and healthcare is interesting – we have largely traded infectious disease for chronic disease. We live longer due to obvious advances in technology and healthcare, but somehow chronic diseases are way higher per capita then they ever used to be.

  10. Although I’ve been a reader since some time, I think i came upon the café via a comment on Jon’s site around 2014-Holuhraun, I never felt the ‘urge’ to post a single thing. I’m more of a reader you know.
    May I put out a suggestion for a writer on the blog? Dr. Erik Klemetti has been searching for a new online home since his leave from Wired.
    Note: I only recently came to know that there is some disagreement concerning Jon’s site, so maybe there are some against Erik as well?

    • Thank you for the suggestion. Erik is a brilliant writer, but he does write for a living and VC is a zero-budget experience – we do not get payment or funding from anyone. So we probably can’t afford him! I am not aware of any disagreement with Jon’s site? I can thoroughly recommend him. Of course everyone has their favourite site and every writer has their own style and topics. Personal preferences are natural. Readers benefit from having access to a diverse set of blogs.

  11. riddle no. 3: Let’s try Tower Hill maar, Australia. It is on public land, so open for all to see.

  12. No 4 is daunting. At first I was thinking of Edsel… but can’t remember what volcano that actually is. Searching on the term yields a dude by the name of Preston Tucker who had some innovative vehicle designs but became mired in stock shenanigans. Tucker + Volcano yields another stuper volcano, discussed by David Tucker here. The center of that activity has shifted to Mt Baker. But I think none of these meet the requirements of the riddle.

  13. “Analyses in the last 20 years have depicted Neanderthals as a powerfully built, archaic hominin specialized to hunt and scavenge large, dangerous prey in cold habitats (3–5). The high frequency and distribution of fractures among Neanderthals matched injuries among professional rodeo riders (6), who interact regularly with large, dangerous animals.”

    With that in mind, this video never gets old. If you will notice, the heavy stocky team members (more neanderthal like) are the ones tasked with trying to overpower and maintain control of the horse while the little skinny guy (an actual sapiens) tries to equip the saddle.

    And no, I am not saying or implying that there was a cooperative hunting strategy, it’s just that you can see the advantages and disadvantages of the the two body types in the video. Particularly at 1:12 where one of them is drug off around the arena by a horse.

  14. That’s the funniest thing I have seen in ages. I guess people do get hurt but I get the impression the horses are quite enjoying getting one up on, too.

    • I don’t remember exactly, but I think one of the requirements is that the rider has to keep his hat on as he makes a single lap. (around what is debatable) I saw one of these in Monterrey California and it was one of the funniest things ever.

    • These horses panicly fight for their lives and there’s no sapiens seen here.
      I don’t have any empathy if some of these homini stulti get hurt, they can decide to quit this bullsh**, the horses can’t and they get hurt too.
      It’s simply disgusting.

      • Sapiens is the standard term for the species. My Stultus theory is not a widely accepted term.

        Paniced? Yes, certainly. But this practice dates back beyond 5000 bc and is part of who we are. A horse is built specifically to run. That’s why you don’t see this particular event done with cattle. Their instinct is to charge and kill threats that are this close to them.

        • Thanks, Lurk. Most of the Horses are well cared for and eventually broken to ride. Or become
          Broncs (or often both) several a famous rodeo
          horses ended up in retirement being kid’s horses.
          My Pop was a horse wrangler-rounded up wild horses for the US Calvary. Last time was 1938.
          They didn’t need more contract stock.
          He tried to join up but was told he was too busted up. -From being stomped on, ran over, bucked off,
          and occasionally dragged around a muddy, manure filled corral…
          Like your neanderthal reference- My
          Cousin (on the Indian side- he’s Nez Pierce/Cherokee ) would be one of those big guys. He’s a Bullrider /Bronc rider and of course, gets busted up every now and then…

      • It’s also why we don’t saddle and ride Pronghorn (Antilocapra americana)… a pretty good example of the winner in a “red queen race” with the now extinct American Cheetah. They are just way too fast to be easily caught. Plus, they probably can’t carry the weight.

        “Their ranges are sometimes affected by sheep ranchers’ fences. However, they can be seen going under fences, sometimes at high speed. For this reason, the Arizona Antelope Foundation and others are in the process of removing the bottom barbed wire from the fences, and/or installing a barbless bottom wire.”

  15. No. 4 Mount Harcourt – Tucker Glacier, Antarctica

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  16. Bogoslof. The compendium shows how the island has changed. Top left is after the 1992 eruption, top right around the December 2016 eruption (image is before, contours afterwards), and from bottom right to left shows Feb, June and July 2017. You are looking approximately south. The rotation may not always be correct – it is hard to find points that have remained the same. It doesn’t look like it is finished yet. Bogoslof normally ends by building a dome to commemorate the eruption, and one did form in June but it immediately blew itself up. So there is unfinished business. Aviation code remains red.

    • It does though often further commemorate the dome building by finishing off with a blast the blows the dome away, either at the end of the eruption, or a few years later.
      All in the name of being a landscape artist 🙂

      • As real estate developer it leaves something to be desired – it is hard to sell the building after you blew it up! The puffins may not appreciate.

        • Nishinoshima is better at building.
          And in regards of volcanic islands…
          The volcano Principato di San Bernardino in the Jebel al Zubair Volcanic Group has lost not one, but two volcanic islands. Both Sholan that was born in 2011-2012 and Jadid that was born in 2013 has mysteriously disappeared in one of the heaviest trafficated sea routes on the planet. What makes it so mysterious is that they where sizeable and deemed as stable new islands. And nobody noticed two horking big booms in the vicinity.

          • Oh, and this is priceless… The Yemen Tourism Boards is announcing that: “Diving, sightseeing, wildlife viewing and volcano trekking are popular activities for tourists and visitors.”
            So, not only is there a good risk for being blown up by the volcano, you can also be kidnapped by Somali pirates, you can also be bombed by the Saudi Arabian bombers that are happily bombing all things yemenite.
            Life, it is just ridiculous…

    • In my opinion, a failed intrusion is probably a successful eruption.

  17. No. 4 – Mount Pawtuckaway, New Hampshire

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  18. M6.4 south of New Zealand. Luckily quite a way south of New Zealand.

  19. How about for 4- Shinmoe-dake – from the Bond movie? You only live twice

  20. No. 1 – El Reventador, Ecuador. Also known as The Ripper. Dr. Strangelove was General Jack Ripper.

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  21. Need more cookies

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  22. 4 – The man (Herbert Hoover), the car (Herbie), the movie (Herbie goes to ….).
    Herbert Volcano on Herbert Island?
    You have no idea how much time I have spent on this. Not as much as one other the great articles on here but more than my employer would wish for.

      • Oh come on! “Doctors” + “abode” and “cold egotistical doctor” points to Gregory House (“Hows”), and the Tarn Hows Tuff Formation, unlike that one in Alaska, is Cumbrian … and is in the Lake District (so, has a “watery abode”).

        If these have more than one right answer, but the “wrong” right answer (or worse, a right answer from the “wrong” person) gets the X, then it’s rigged, pure and simple. 😛

        • Then how cv ome I have only gotten one correct answer in the entire time we’ve done these? (And my answer was spooky in how it happened)

        • First of all I make the riddles, and I produce the answers in advance and I write them down.
          Upon occation someone comes up with an equally good answer, and then I award a bonus point.
          In this case your example is not even close to good enough though. Why, it had almost nothing to do with what asked for.
          Doctors watery abode: Doctor = equal MD or Ph.D.; Watery abode = Island (Isle)
          Egotistical cold doctor: Egotistical = self vain (how the heck are you more so than incorporating yourself into the riddle?); cold = I am farkin’ Swede (cold as they come); Doctor = once more…

          I always give the answers beforehand to someone else in case I am busy, as it has been since we opened this place.

          In the end, our judgement, our call. Up to you if you wish to play. I never do favourites.
          And before you insult me further, that person is never allowed to answer. This time around it was obviously Gaz.

        • I am glad to see that the riddles generate strong emotions! They are fun and engrossing. I was disappointed at not getting anywhere myself (I did think that Iapetus suture was a plausible one for no. 1, (Iapetus being the ocean, and the suture the stitch (medical term, thus ‘doctor’) where the ocean disappeared in the subduction, which runs across Cumbria) but sadly no ding.) (The weakness was that this suture is found elsewhere as well, not just Cumbria.). Obviously, if you know the correct answer (which I don’t!) you do look different at suggested solutions. Keep trying!

  23. The fires on Vesuvius give an uncanny resemblance to the 1872 and 1944 eruptions! Surprisingly there doesn’t seem to be much fear-mongering going on about it…. for now, at least!

    • It’s Italy. If anyone says anything one way or the other, you can rest assured that some lawyer will try to make it into a retirement income. The down side is that should someone get alarmist about it, actual geologists will likely be reticent to correct them.

      Caveat: I’m not Italian and know very little about the culture. I do know that I got my foot ran over in Naples, but it was a small car and I didn’t really notice until I looked and saw the tread marks on my tennis shoe.

  24. Been a while since I dropped by (Bardubunga time period). Saw a interesting earthquake on some helicorders when I woke up today and wanted to see what the experts around here thought of it. 🙂 It’s not in a volcanic zone (thought it’s only about 50 miles from a very long dormant one), but doesn’t look tectonic to me.

    Broadband vertical recording:

    Long period vertical recording:

    This is the helicorder closest to the earthquakes occurring near Lincoln, MT. The M5.8 tectonic quake a week ago, then a lot of aftershocks, and then the above recording. See the July 6 recordings for the M5.8:

    • The frequency is that of seismic vibrations coming from ocean waves: However, it is rather far from the ocean and the signal looks artificial. Could it have been a seismic drill? They are used in boreholes to generate waves so you can do seismological mapping of what you are drilling through. You can use geophones to detect the reflections.But others know much more about this.

      • Note in the upper plot it is a single frequency, of order 10mHz. There doesn’t seem to have been a strong distant earthquake and it was not seen (I think) on other seismographs n the area.

      • I admit to not checking the timeframe for an earthquake, so I could be wrong on that.
        That being said, at Missoula it can’t be waves. Unless of course Godzilla is splashing a few kilometers away. The ocean is to far away.
        Baring a teleseism it is most likely an enginge of some sort.

        • That is what I thought. The low frequency is not a normal engine but it would fit drilling. The time (after midnight) is a bit funny, but not if it was a seismic mapping exercise, i.e. the signal was generated deliberately. Alternatively: could it be a reservoir being drained? It is a bit too regular for that though.

        • Thanks Albert and Carl – knew you’d come through. It does show up on other seismographs in the area, but far weaker than at Missoula. You can check out them in the last link in my original post. This, for instance, is the Dillon, MT signal, which is why I was thinking something fairly close to Missoula (strongest signal), not distant:

          • If you can work out the travel times, you might be able to derive a rough epicenter estimate. I would stick with just the P phases, the other ones entail bounce and multibounce off of different layers. The “degree” bit refers to the angle of measure on the surface as seen from the Earths center.

            This link uses the IASP91 Earth model.


            The actual degree measure depends on which radius they use for a standardized Earth in the model. If you swag it, it’s 111.1329444 km per degree for the meridional Circumference, and 111.3194917 km per degree for the Equatorial radius. (111.2262181 km per degree is the average if you want to try and use both.) Using the average will get you into the ball park, but if you really want to nail it down, you need to look into what IASP91 uses for a Circumference… so it’s your choice, speed of coming up with something or trying to get a more accurate estimate of the position. There is easily a lot of philosophical argument that can be made for either method. A technician would probably go for the speedier method, an engineer would probably go for accuracy. As a technician, I try to not get caught up in details that won’t help me correct a problem or that would delay getting a system working. Yet I have fallen into the same trap that I try to avoid and don’t have the answer that you are seeking. But, at least I pointed towards a method of answering it. (note, the timing errors for each station will introduce ambiguity on top of just trying to figure out the travel times… so even if you nail the accurate answer, there will still be a lot of room for error.) {and this is also why researchers who do in-depth analysis of quakes at a later date use revised and more accurate seismo data since they can get at and correct the actual systemic errors in the network}

    • sorry that’s wrong, its maybe: Billy Mitchell Papua-Neuguinea

  25. In regards of No.1, people overlook the “cold” part, or does not take it literally enough. 🙂

  26. Really bored and therefore spent some more time

    Mt Carlisle Alaska, Carlisle in Cumbria and (another) google search is there is a Dr Carlisle in Twilight who may be a vampire and therefore cold as well. (honest I have never seen it)

      • A faster dance around the office with some fist pumping!!!

    • It was actually a reference to the usual Dr Carl in here (me) and it is a watery abode (isle). So, I tormented everyone with myself, hence it is egotistical. And the cold part, well it is in Alaska.

  27. The riddles have all been answered. Thank you for all your guesses and congratulations to those who guessed correctly.

  28. I would like to thank everyone who participated in our volcanic riddling.
    Since it was once again a hit they will be recurring from now on.
    Hm, time to make some real brain-crackers 🙂

  29. A 5,800 square kilometers iceberg weighing one trillion ton has broken off the Larsen C ice shelf. I was curious how many pounds that is so I got on Excel and it told me 2e+15. If I calculate that correctly that’s 2 quadrillion pounds. That’s a lot of cheeseburgers!

    Found eating the cookies in the dungeons again! – admin

    • I saw some other back of the envelope math yesterday, can’t remember the weight, but it was in the rather high area, like your calculation. However they then went on to calculate/claim that the weight would be too large to move by mechanical means, even if you used every single ship on the planet at the same time to pull it.
      I don’t know if the math was right, but it is fasinating that an icecube can be that big and heavy.

    • Yes, that number is correct. The ice is about 200 meters thick, by the way. It is about 0.5% of the total amount of ice in Antarctica, or 12% of its total amount of sea ice. Antarctica is losing about 70 billion ton of ice per year (net), so this single iceberg accounts for 15 years of ice loss. Which may well be how long it will take to fully melt.

      It is also about 25% of the entire summer sea ice amount in the arctic ocean (that amount has gone down by a staggering 60% since 1990). It could have raised sea levels world-wide by 3mm, but it won’t as it was already floating.

      A calving like this is not that unusual though. The main question is whether the remaining ice shelf will grow back, or disintegrate. At the moment there is no indication that the ice shelf is disintegrating.

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