The (ash) history of Iceland, in my backyard – Part I

This week I was lucky enough to have a recently dug square hole (10m per 10m, about 2 meter deep) some 200 meters from my house in Southwest Iceland.

Needless to say I spend the past bright summer evenings of Iceland inside this hole, which has nothing else but dirt and rocks. To us, volcano lovers, having such a hole in a volcanic land is like finding a mine of gold!

The soil shows many layers of colored material, which is nothing but the ash that has fallen from the many eruptions that happened in Icelandic history. This is a science called tephrachronology and it became my newest hobby.

Photograph and copyright belonging to Irpsit, used on explicit permission by Volcano Café. An excavation near home. And I stayed until late night to look at its strange layers.

When an eruption happens (if it’s the explosive type) the ash usually drifts according to local winds. In Iceland, the wind can blow from every direction depending on the kind of weather. This results in ash being deposited in a space-specific way for every different eruption.

A large eruption such as Askja in 1875 (VEI5) blew almost entirely to the northeast (so since I live to the southwest, I cannot find any Askja ash). In practice this means that the absense of a famous eruption does not mean it did not happen, just that the ash blew somewhere else. Likewise, a smaller eruption can deposit plentiful ash if the same wind keeps blowing in one direction (example of Eyjafjallajökull blowing southwards towards Europe in 2010).

In one single spot, the ash from different volcanoes accumulates over time, giving a profile of layers, that correspond to a time orderly of eruptions of different volcanoes. Usually, famous eruptions such Vatnaöldur in 870 (when the settlers arrived) can be used as markers for less known eruptions. The identity of a volcano can be roughly identified by looking at its color. We know that few volcanoes in Iceland produce white tephra, only Hekla and the rarer eruptions of Öræfajökull and Askja. Grimsvötn often produces brown ash, while Katla or Eyjafjallajökull black ash.

But enough of introductions! Let’s go for the real thing.

Photograph and copyright belonging to Irpsit, used on explicit permission by Volcano Café. The history of many eruptions is recurded as different ash layers.

The walls from the hole reveal, at instant glansing, two bright WHITE layers (figure 1). At close inspection, the upper white layer (at 25cm) is actually a double of two light colored layers, while the lower at (49 cm) is a single thick layer. Obviously these layers seem to come from Hekla.

The Hekla 3 white layer
To confirm whether or not these are from Hekla, there is a scientific paper of a soil profile done very near to where I live, around Grimsnes volcano (just 5km from where I live). They found only one large white layer at 50cm which corresponds to the largest eruption of Hekla during Holocene, the Hekla 3 eruption (a VEI5+) of 1000 BC. This is probably our second and largest layer.

Picture taken from Wikimedia Commons. Hekla is the source of much white ash in Iceland (as observe from the deposits on its flanks).

So, imagine, an eruption that deposited a layer of about 4cm thick ash here. That is pretty astonishing considering that a normal Hekla eruption barely deposits ash here (I am about 50km from it). This euption resulted in a 18 year climate change in Europe, observed in tree rings. It should have been one big huge eruption.

Now, if we look at the top white double layer, that is surrounded up and down by two thick DARK bands. These are actually a pinkish brown. Both are about 3cm thick ash (impressive too), the lower band is especially large at some spots.
The two dark Bardarbunga ash bands
According to other studies (and to Inge B), and also my conclusion, these are both the Veidivotn ash (1477) and the Vatnaöldur ash (870 AC), known as Settlement Ash (because it happen around the arrival of the vikings to Iceland). At least the Vatnaöldur ash is widepread reported everywhere in Southwest Iceland. Furthermore both have orange colored deposits underneath (actually light pink in Veidivotn ash, and bright orange in Vatnaöldur ash) which is expected. Both eruptions started with rhyolite ash from Torfajokull followed by the greyish/brown color of Bardarbunga fissures. The Torfajokull ash in 1477 was erupted from Brennisteinsalda, which is a mountain very colorful but mostly pink and orange.

Brennisteinsalda is the volcanic cone that erupted some colorfull rhyolite in 1477 (within Torfajökull).

The “double” white band of Hekla 1104 and 1341
If these are correct (I don’t confirm they are), then there are 2 white tephra eruptions in between. It’s easy to ascribe one to Hekla in 1104 (the largest eruption of Hekla since settlement (and second largest of all volcanoes), a very destructive one, but the ash during that one, was reported to go mostly northwards). The other one could either be the eruptions of Hekla in 1300 or 1341 (both with heavy ash) or less likely the 1362 eruption of Öræfajökull, which was the largest eruption of all, since settlement! Yes, larger (in tephra and intensity) than all Katla eruptions, Laki, Veidivotn, Askja or Hekla. Few of you know that Öræfajökull is a mamoth volcano, the largest in Iceland (and tallest).

However, I do think that this more recent white layer, was most likely the 1341 eruption. In 1300 the ash blew mostly northwards resulting in a famine, but in 1341 it blew westwards, and quite far away (towards Akranes). In 1362, the ash of Öræfajökull blew mostly to the southeast, opposite of where I am (and I know little ash felt to the west, in Vík – information from Skaftafell national park).

There is so much I write in a second part. All the minor layers in between (that you only see in close-ups) and all the broad bands below Hekla 3. Until then, let’s us discuss what we have so far.

IRPSIT

593 thoughts on “The (ash) history of Iceland, in my backyard – Part I

  1. 16 Santa Cruz de Tenerife has a wonderful concert hall, and a world class symphony orchestra, I saw a performance by them; there of Ravel’s “La Valse” he was a great yet modest composer 😀

    • I did a TV ad for a computer company in La Palma, a contest whose prize was a trip to Rio.
      Once, I was in Rome, and I was even recognized by a musician “canario”.
      I might still be a celebrity on the islands!
      Besides, Lanzarote was home of Nobel prize winner José Saramago and location for a Woody Allen film.
      How do we get there from Brazil?

      • Well as a celebrity, you really should visit the Canaries why not try RyanAir, you may get trampled on while trying to board, have to paddle all the way, and not use the toilet & tiy definitely won´t get any free food, but hey ho – they have got to be the cheapest.flights…

        • Oh no, forget that advice Renato Rio – RyanAir have just announced that they have reduced the number of flights they have to the Canaries as they are complaining the the Spanish Government have decreed that they cannot pass on new airport taxes that have just been introduced to the travellers that purchased their tickets well before the new rules came in….they (RyanAir) reckon that by reducing the amount of flights to the Canaries, they are going to reduce the number of tourists visiting the islands by about a million, and that at least 1,100 people will loose their jobs as a result…I just hate it when you see a prime example of big businesses being so nasty – it is like the are telling Spain – stuff you, there is no way we are going to be fair to our customers who paid us well in advance, if you will not allow us to pass on new taxes to the customers, we will stuff you good ´n proper buy trying to wreck your tourism industry…………well I am sorry but what a sad state of affairs…I would not recommend RyanAir to anyone….the only 2 occasions I have flown with them have been well sub standard compared to other airlines….

          • sorry forgot to say where i read that ..it was in the English published fortnightly newspaper called “Island Connection”s (www.islandconnections.eu)

          • Everything is relative.

            I have flown on Ryanair from UK to Nyköping in Sweden and back for 2 pence (and I mean 2 pence, not 2 pence plus taxes, card fees, check-in fees etc). The service was really rather good at that price!

          • Ukviggen, how on earth did you do that since they charge 25 euro for using your card to pay the ticket?

          • Haha – you have to play the game. For a while if you had a certain type of debit card (pretend to be a humble student) they didn’t charge a handling fee.
            The other great wheeze (loophole since closed) was to buy Ryanair gift vouchers – you could buy them on a credit card without any handling fee, and then redeem them at face value.

          • I rather pay, get some service, and not having an idiot waking me up every five minutes by shaking my violently to sell a lottery ticket. Then dumping me at a closed down airport, before telling me that they cancelled the returnflight a week before I flew there to beginn with, without of course telling anyone, and that they are not going to pay for anything even though they horked it up.
            If any terrorist starts blowing up Ryan Air they are not terrorists, just getting even after getting butt-horked by them…

          • I agree. Sadly (yes, I mean sadly) the great Ryanair heyday is gone. They are now usually more expensive than much more comfortable and agreeable alternatives, especially if you are prepared to dig around a bit on the net.

            Why do I say sadly? Well, a few years ago you could get some crazy prices for flights (such as my 2p return) and that opened up travel that would otherwise just not have been possible. We would quite often just go somewhere weird for a weekend – didn’t really cost much more than staying at home. Over to the Ardennes for the autumn leaves! Ooh, Biarritz looks nice! Who fancies a couple of days in Almeria in December? It’s asparagus season in Berlin! I’ve never seen the Giant’s Causeway ….

            But, on the other side of the coin, I have been stranded by them in a field somewhere near Gothenburg*, and only got home by getting a through-the-night bus to Oslo.

            * Fact: Gothenburg is the one place where the airport that Ryanair uses (Säve) is actually closer to the city than the airport where the proper airlines go (Landvetter)

          • You seriously have got the wrong end of the stick. The pieces of shit, excrement, scum, filth is, as usual, the moneygrubbing politicians who will tax just about anything in order to get their greedy, criminal hands on as much money as possible which they then squander without anyone ever being able to audit their shenanigans. It goes to support the lifestyle of people such as Perfidio and nemesio. And please do remember, most of the money taxed goes to support these scumbags and not to the taxpayer.

            More power to Ryan Air for standing up to the thieves!

          • Well, I also hate Ryanair for various reasons, not in the least including their way-shorter turnover time at airport than any other airline. It is 20min for Ryanair and usually not less than double that or more for normal airlines. Are you really sure that Ryanair can make all technical security checks twice as fast as anyone else? Yeah, sure. Not to say anything about overworked pilots and crew who are required to work longer in one stretch than any other airline. Do you really want to be flown around with sleep-deprived pilots? Have you ever saw Michael Leary non-chalantly brushing away all and any safety concerns all in the name of getting profit and profit and nothing else? Plus of course they cancel on you without telling you and bother you with lotteries, etc. Make no mistake, I do fly low cost airlines, just not Ryanair!

            And finally, the Canaries are not going to happen with Ryanair anyway, becuase, if you haven’t heard, they are cancelling the majority of flight to Spain from next month, because Spain increased airport tax (carbon tax, I think)…

          • (Warning! This is a Joke!) Michael Leary of RyanAir walks into a pub and sees that beer is only 1p a pint. He is amazed but asks the barman for a pint. “Sure!” says the barman, “Will you want a glass for that? They’re only £3.50 each.” (Boom! Boom!)

          • I like that joke talla, perfectly sums up Ryan Air in my view. Sister travelled with them, got charged an extortionate amount of money for one bottle of water!! She needed to take tablets and apparently they don’t serve free tap water on Ryan Air. 😛

  2. First EQ over 2.0 in a while.

    ‎1158542 26/07/2012 19:09:01 27.6585 -18.1237 21 2.1 4 SW EL PINAR.IHI [+]

  3. 17 Cesar Manriques house on Lanzarote, he was an artist/ architect/ Francoist… but he built his house on a lava flow near Tahiche, and for a basement/ garden / bedroom he had an awesome lava tube divided into rooms, the schkylights were naturally occuring…

    • oh yes I have been there, what a pad that was…very impressive, not sure I would have wanted to live there, but certainly it can only be described as “awesome”

    • Its 1 thunderstorm rolling through the midwest. Each city does their own warning. It’s very much the norm. Nothing much to see here, I just got hit by the storm. It rained, some wind blew, but nothing worthwhile happened. Just another thunderstorm.

    • We had that number of flood warnings in the UK a couple of weeks ago. I think they are desperate for the rain in the US.

      • Yup, we’ve been getting a bit more rain recently, but considering the drought, more rain is always welcome.

  4. Looks like there has been a bad storm in Madrid aswell.

    ,,En Madrid nos hemos que dado sin internet y sin luz en las calles por la tormenta de rayos,truenos y chaparrones…por lo menos por el distrito de Chamartín, quizá habeis tenido problemas para conectar con IGN….

    In Madrid we have that given without internet and without light in the streets by the storm of lightning, Thunder and downpours… at least for the District of Chamartín, may have had problems to connect with IGN…. (Translated by Bing) ..

    https://www.facebook.com/pages/Actualidad-Volc%C3%A1nica-de-Canarias-AVCAN/163883668446

  5. Most of the newer medium shallow earthquakes under El Hierro appear to be located within the swarm preceeding Bob. This rotating 3D plot shows all earthquakes from 01/09/2011 to 26/07/2012 (19:09) colorcoded by date and sized by mblg, except for the last 70, they are the big blue squares, later ones are bigger. The 0 km ones are omitted, because I think that is the default for undetermined depths.

    Carl pointed out that as long as there is no harmonic tremor present, magma should not be on the move. Why is that old swarm area so earthquake prone since a few days?

    IGN gives the location of the earthquake near the surface different locations. The plot is with data from the El Hierro boletin list. If I plotted it according to the homepage list (http://www.01.ign.es/ign/layoutIn/volcaListadoTerremotos.do?zona=2&cantidad_dias=10) it would be closer to the second from top. Confusing. That would be where several shallow earthquakes happened during July.

    • You might try poking around to see how they relate to the early circular artifact. It showed up as a region mostly devoid of quakes in the first week or so. We never really came to a conclusion about what it was.

      • Hi Lurking

        I thought thet the article with the tomography gave the start of an asnwser ?
        Old magma solidified, so no much cracks to get in ?

      • The article gave a hint as to what it might be.

        Just because and idea makes sense that doesn’t mean you stop questioning it… not without hard fact.

        Unless someone digs a mine down there and looks, or something lofts it out of the ground as an intact plug 1 km across, we will never know for sure.

        • Last night I could not sleep very well, 30 degee celsius, thunderstorm here and then and in an endless loop I wondered how to plot a hole…

  6. Hi all, Fredrik that was a great comment that just lost to me, but I read it now.
    OK, I am more convinced that Vedde is from Katla. I could not see how researchers could have made such a mistake, so obviously I was the one wrong. If its a dark grey color then it looks like coming from the proximity of Katla (where we often find this type of colored ash, and if they find a similarlity to Katla basalts, then it reinforces this idea).

    This eruption was probably the largest or second largest of Holocene in Iceland, in par with the Grimsvotn 8000 BC ash. And now we need to find the ash for the Carl’s large Askja eruption also about 8000 BC. (so much post-glacial activity makes me crazy)

    Well, I actually have another candidate for this BIG eruption: Tindfjallajokull. It has a sharp 1500m high peak like it never has been shaped during a glaciation period. So it must have had a large eruption in these last thousand years. Researchers have said it was once the largest and tallest volcano in Iceland, and blew in a huge VEI6+ eruption about 53000 years ago, This is the well known Thorsmork ignimbrite. Looking at the site itself, you have the idea that this was something like the Nova Rupta or Krakatoa eruptions: really blowing a big portion of the mountain itself. And this is just a couple kms west from Godabunga and north from Eyjafjallajokull. Well, you have one of my Icelandic’s favourites.

    Read it here
    http://www.agu.org/pubs/crossref/1996/96GL03099.shtml

    • Heidi Ritterbusch from Copenhagen offered her thesis on the Thorsmork Ignimbrite over at Eruptions back in the days of Eyjafjallajökull. Did you get a copy? I am sure she’d be happy to send you one. I can email her if you like.

    • I’ll try to sum up some of your questions here, it got a bird hard to keep track of everything. I’m not familiar with the marine limits in Iceland, but 70m up doesn’t have to be above Holocene sea level, depending on where you are. If you want to determine past sea levels raised beaches can be effective yes, but I don’t know how well they are preserved in volcanic rocks or in Iceland generally. Abrasion marks will be weathered away pretty quickly though, it’s easier for us who have e.g. massive granite which can be resistant for a long time. The best way to visually find marine limits, however, is to locate larger glaciofluvial deltas, as these are deposited in the sea by the receding glaciers. You should consider tectonic episodes and tephra covering the deposits, again it’s a bit easier in my country 🙂

      “Second question, if there is a shield from interglacials before the ice age, should I expect it something specific, other than being more eroded than usual?” I don’t think I understand that one – what ‘shield’? If you’re down in a layer with alot of different grain sizes (everything from boulders to clay) and it’s consolidated, it’s likely that it’s a basal till. The fabric should be subrounded, but that varies alot with regards to transport distance involved.

      We do locate subtill (old) sediments in some places, but that depends on the locality. Usually almost everything is eroded. The subtill sediments imply that the glacier have been advancing over the sediments, but it hasn’t eroded all of it away. At these spots, if one has a decent stratigraphic overview of the sediments, one can see that the weight of the glacier has deformed the sediments, hence the term glacial tectonic.

      Back to the Vedde ash layer – it’s dated to 10,600 – 10,300 14C years BP – so that’s around 12,000 calibrated years ago. Very much in the middle of the Younger Dryas chronozone. It looks like the Katla region atleast, so your guess might be as good as any’s. Didn’t I read a paper on the mixture of rhyolites and basalts in Katla and how it made prehistoric/historic eruption pretty huge?

      Saksunarvatn is AMS dated to 8930 – 9060 14C years BP – so around 9930 – 10,010 cal yr BP, so at the transition Preboreal – Boreal.

      In terms of colour and appearance I’ve got a couple of papers I can send if you’re interested. Did I cover most of the questions btw?

      Looking forward to part 2 🙂

  7. I think somewhere near Hamarinn we are experiencing what looks like harmonic tremor:

    There has been a few deep quakes over there, but not so many recorded EQs as the tremor graphs shows. Magma is on the move, near Joklasel. Culprit is quite localized near Hamarinn. Doesn’t show in other stations besides Skrokkalda.

  8. Another update in Iceland. Krisuvík “central” lake has now lots of dead fish, it means hydrogen gas has been flowing into the lake, and making it acid and toxic. This lake (which is about 3km long) nearly dried in early 2011 (and exposed hot springs) but recovered much again in 2012. It seems that it will be increasing in activity again.

    • A sharp decrease in pH in spite of the recent huge inflow of water means one thing – magma close to the surface. Seriously interesting update, thanks!

    • Wouldn’t be surprising. There was a big swarm there about a year or so ago. We all thought it was going to be the next Icelandic eruption (then Grimsvötn stole the show).

  9. I’ve got a semi-workable routine for estimating SO2 output from the Tio2/FeO ratio. It’s based off the formulas in “Preservation of Random Megascale Events on Mars and Earth: Influence on Geologic History” by Mary G Chapman and a work up of the upper and lower bounds of the Sulfur production rate. Per the book, it gets to within about 15% of the emitted quantity.

    In order to do a calculation, I’m gonna need to find the chemistry of the tephra for that eruption, so, if it can be found, which one ya want me to do?

    My estimates for the 1783 Laki come out at between 55.0 Mt to 202.8 Mt… with the center of the estimate at about 121.3 Mt. This is about 1.2% to 2.4% of the amount emitted by a flow the size of the Deccan Traps. (same reference)

    • Well… [insert desired expletive of choice here]

      I’ve been messing around with that formula a doing some calcs. Using a representative average of the TiO2/FeO ratios for Yellowstone… I get about 19.6 Gt of SO2 emitted during the Island Park eruption… give or take 17%

      For the other two, 8.0 Gt for Yellowstone proper, and 1.9 Gt for Henry’s Fork.

      By comparison, Toba reportedly erupted somewhere between 2500 to 3000 km³ of material, based on it’s TiO2/FeO and size, that’s 12.4 Gt to 14.9 Gt.

      Oh… and not letting a good Yellowstone post go with out some bashing.

      You know that meme about Yellowstone erupting every 600,000 years and it’s been 640,000? Well, first, it’s horse shit. Volcanoes don’t do schedules. Trying to shoehorn something like that into a schedule is ridiculous. You also don’t make sound estimates off of three data points.

      However, if you really want to go that route…. the actual average is 735,714 years, give or take 926,382 years… and change (1 SD). That will give you the Normal curve that actually fits the 22 known large caldera forming eruptions of the Yellowstone hotspot.

      Reference… one very cool paper.

      http://www.ldeo.columbia.edu/res/fac/argon/Publications/anders%20et%20al%202009%20gsab.pdf

    • How about the ratio amount x time (k- years?)?
      I am still not convinced of Carl’s calculations regarding the average emission volume of Icelandic volcanoes as keeping the pace of the Siberian traps, but my Maths is too short to make my point…
      As though I loved the whole of Carl’s post, I thought there could be a miscalculation at some point…

      • Just to remind Carl’s words:
        “What is today known as the Icelandic Hotspot has been conveying about the same amount of magma since the Siberian Traps. Give or take the eruptive rate has constantly been around 0,5 to 1,5 cubic kilometer per year since day one. “

      • Renato,

        Siberian traps – area 2½ million square kilometers to a depth of between 3.5 km (Norilsk) to less than 1 km (Nizhnyaya-Tunguska). Volume estimates range between a low 1.3 M km^3 for present day to 4 M km^3 original

        Iceland IP – area above sea 0.103 M km^2, estimated total extent 0.5 M km^3. Thickness between 15 and 40 km (under land) of which ~4-5 km may be original sea floor, giving between 10 and 35 km thick deposits. Average thickness over the entire Igneous Province, subaquatic or subaerial, about 15 km.

        Siberian traps 1½ – 4 Mkm^3 – Iceland >6 Mkm^3

        Now figure in the time factor, a maximum of 2½ – 3 million years for Siberian Traps and ~20 MY for Iceland. Hmm… Unless my figures are wrong (GIGU), you do have a point as the output 250 MY ago seems to have been at least double.

  10. From E/V Nautilus in the Aegean Sea , south Turkey
    Current Status
    “We are preparing for our first dive at the Anaximander seamounts south of Turkey in the Mediterranean Sea 46 min 31 sec ago”
    They are going to explore these seamounts so it should be most interesting geologically. I will ask the crew if there is any volcanic activity seen there. It is an old subduction zone so probably not.
    http://www.nautiluslive.org/

    • Morning Diana
      They just said that there might be active venting.
      I can only access channel2 are the other ones working for you?

      • Only 2is working as they descent. the Quad is having problems I think Channel 1 will probably work when they land.

    • The ROVs are nearly on the sea bed. I have asked about volcanic vents. There is a geologist on board and also Nichole who is a biologist with an interest in the life forms in volcanic areas. Evidently they dived here 2 years ago and there was some gas vents. So this should be an interesting dive for us in Volcanocafe.

    • Good morning Renato. Hekla looks cosy 😀
      You are in IcelandI am 2500 ft below the Aegean sea looking at the geology of the sea mounts there. 😀 Isn’t it amazing what we get up to here:D
      Shouldn’t you be in bed by now Renato?

  11. Hi

    Here is new video posted with 3D view of the present earthquake swarm. It comes from June 24 to yesterday.

    http://eruptionelhierro.blogspot.fr/2012/07/3d-video-earthquake-june-24th-to-july.html

    This is in 3D with the coordinates and the profile of the island.
    Depths are in hectometers, height (for the island) in meters.

    Azimut varies from 0 to 20°. The view rotates constantly.

    After the initial fast progression from under El Golfo and the island ridge, at 15 to 20 s we can see the outlines of the swarm taking shape under the western part of the island.

    At 32, 35 and 37 s, you can see the 3 main zones of earthquake accumulation from different angles.

    Then between 40 s and 1 mn, the “Orchilla” zone develops. After 1 mn, the EQ seems to scatter more and the zone seems to get more diffuse.

    Please not a small cluster of 4, appearing after 51′ up over 5 km near Tacoron. There seems to be 2 more around 1’20.

    • Hi Lucas. No Renato is fast asleep at the moment in Brazil. I was just commenting earlier how amazing it is that he could also be visiting iceland and I, sitting in a sunny at the moment, North West England am also diving beneath the Aegean sea!!!!
      I just still find the internet absolutely magical.

  12. A few days ago i was looking at Canadian volcanoes on the GVP site. I came across a very interesting volcano called Crow Lagoon.

    GVP Summary:

    Thick beds of basaltic tephra of Holocene age originating from an unknown Quaternary volcanic center have been found near Crow Lagoon, north of Prince Rupert near the southern tip of the Alaskan panhandle. Ballistically emplaced bombs imply a nearby source, which remains unidentified (Souther and Weiland, 1993). The tephra beds are located along the south side of the Khutzeymateen Inlet, about 40 km north Prince Rupert.

    I would like to propose an idea, looking at the landscape, the most likely source of the deposits found near Crow Lagoon… Is Crow Lagoon.

    Think about it, Crow Lagoon forms the perfect shape (http://mw2.google.com/mw-panoramio/photos/medium/49716320.jpg). Look at the circular walls, the way it stands out from the rest of the landscape.

    What are your thoughts?

    • I see what you mean, looks like a pressure wave leading to condensation .. hang on, that must be a trough in the pressure wave – isn’t it a drop in pressure that leads to condensation?

  13. @ Spica, Carl and other dragons re spam in Treasury:
    yesterday I suggested to close comments on Treasury main page, but I could not actually find a way to do so on one page only (either at all pages or nothing).

    Another suggestion is to change the permalink to the page, so that the URL is renamed. I think this should stop spam at least for a short while, but it won’t affect commenting by real people or anything else.

    If you think this is a good idea, here’s how to do it (on Spica’s request 🙂 ):
    Go to Pages -> Treasury -> Edit, then just under the top field with the title (Treasury), you have
    Permalink: http : // volcanocafe. wordpress. com /gems/ (writing this out as non-link), which has and Edit buton next to it. Click on this and specify something else than “gems” and save.

    • Done it. I changed the nae for now and the old page is no longer in the menu but not yet completely deleted. The new one has a different permalink. So lets see now, if it is the name or the many links that attract spam. If it is the links, we cannot change it for the moment and that would mean for the dragons… a lot of fodder the few days. I am keeping an eye on it, so no worries.

      • Is this to Bob (during 10/10/2011) or the whole of October 2011?

        Apologies if you have already explained this earlier (I could not find your earlier comment).

        • Hi KarenZ, it’s up to the 11th so it stops just after Bob starting up.

          if you like it I’ll do more plots but it is ‘puter time consuming, ie for the previous video (june 24th to 26th july) it took about 8 hours for 2400 points.

          • The plot is fine; I just wasn’t sure of the dates.

            Only do more if you want to; 8 hours is a serious time investment. What software are you using?

          • Octave (Matlab free clone), which is fine for vector nad matrixes but veeerryyyy slow for loops. But it has handy functions do to the island map with gridding.

    • Watched the video, itself, from AntarcticSurvey. The dimensions of the valley weren’t clear nor was the type of rifting; they were looking more at the effect of the presence of the rift valley as a means to transport warmer ocean water under the icesheet to cause melting further inland than might otherwise be expected.

      There was an interesting feature in the video which was not discussed. There is a warmer area inland as shown on this extract (most melting red; least blue)

      Source for the image: http://www.youtube.com/watch?v=VZd47gfsfuA&list=UULRaKJeCPEe362Z_rLaEnag&index=1&feature=plcp

      Could it be volcanic / geothermal activity?

  14. It is friday. I have nothing planned for today, so no Name that Lava from my side. Alan sent a riddle though which i could hane out without a post. I dont know if Carl has anything up in his sleeve though.

  15. Dunno where the Keepers are so……..
    Sissel – your sleepless nights start here

    Dark, sun-tanned apple juice? I am not, but I’m nothing without water!
    What am I?
    In what and with what am I found?

      • Not planning one unless Carls says i should. and if he does on i ll just add the riddle. Irpsits post is so nice… and hardly anyone reads old posts….
        Btw no spam the last hour. it was going to the old page, .. which is deleted now. So spam seems to have to do with the age of a page, (and maybe the nae too) lest wait and see. And if we get less spam but spam starts coming in on newer pages in a few weeks, then i will ask Carl to write to his wordpress- technician- friends.

    • Siderite, carbonate of iron, formed during the hydrothermal stage of mineral crystallisation but can occur in sedimentary rocks. And a very happy birthday to you!

  16. I will be probably be away for the weekend. Its a sunny and warm start for the weekend in southwest Iceland. I will take a shovel with me, just in case I find some spot to dig ;D

  17. ER are reporting the rise in deformation of PINA and that magnetism values are high.

    ,,On the other hand PINA shows a 1.5 cm climb today, a very strong deformation if the Ultra Rapid data are confirmed later on.
    – Reader Roland reports that the Captain of the Atlantic Explorer, currently cruising the Las Calmas sea made a statement that magnetism values are very high, probably due the presence of a lot of iron the the moving magma below the sea bed.,,

    http://earthquake-report.com/2011/09/25/el-hierro-canary-islands-spain-volcanic-risk-alert-increased-to-yellow/

    • Problematic.

      Liquid metallic minerals do not really posses an inherent magnetic field. The amount of flow needed would be rather large and depend on the induced current as the conductive material flowed through a residual field… in order to generate one of it’s own.

      The field measurements that were done as mentioned in that paper the recently identified the old vent structures, was measuring the field as frozen into the solidified magma. That field is a result of what the Earths field was at the time.

      There is a hell of a lot of math involved in making even a rough estimate of the magnetohydrodynamic forces in play…. far beyond what I can muster, but based on what I do know, it probably wasn’t molten material causing the transient. Maybe regurgitated solid material… but not molten.

    • Say you have a medium mixed with randomly oriented magnetic bits and pieces, the net magnetic field would be 0.
      If you melt the medium, the bits and pieces could align and form a single magnet with a strong field. This becomes permanent after the medium solidifies.
      A problem is that all ferro or ferri magnetic materials loose their special magnetical properties above the curie temperature, 600-770 celsius. They loose their magnetism even after they cool down unless they are remagnetised by a strong field.

    • Well Bob’s far from done yet, He’s got a lot of heat to dissipate. It is probaly quite “not too ” unsafe to dive around here as long as you get a rope around you. I’m far more concerned by the oxydation state of the bottom left screw

  18. Dark, sun-tanned apple juice? I am not, but I’m nothing without water!

    I’m nothing without water…. a sea? No sea without water? Nosean (or Noselite; not dark = light = lite??)? Belonging to the Sodalite group of minerals (soda is nothing without water either).
    Wikipedia: “a mineral of the feldspathoid group with formula: Na8Al6Si6O24(SO4). It forms isometric crystals of variable color: white, grey, blue, green, to brown. It is found in low silica igneous rocks. There is a solid solution between nosean and hauyne, which contains calcium.
    It was first described in 1815 from the Rhineland in Germany and named after the German mineralogist K. W. Nose (1753-1835). The mineral is rare but widespread..”
    Don’t know if this makes any sense (yet). But still one night or two to go.

          • Well sorry, but you are wrong, saw plenty of geese and even a horse in the stadium just now! I don’t really get what this whole “village” image has to do with olympics though. For those not watching yet, the whole central part of the olympic stadium is shaped as a village, with a cottage with smoke coming out of the chimneys, flocks of geese and a couple of geese herds, a horse ploughing a field, etc.

          • What has the NHS got to do with the Olympics I am totally lost with this and whats that all about a baby with gigantic head think someone has lost the plot with this!

          • The olympic flame lightning was fantastic!!!! And the fireworks!!! Well spent council tax on that bit, Karen. 😀
            Although I don’t think the rest of the ceremony translated well (if at all) to non-British audiences, except the arrival of Queen with James Bond, that was hilarious.

  19. “Dark, sun-tanned apple juice? I am not, but I’m nothing without water!”

    Black jack, also known as spharlerite (zinc sulphide, ZnS).

    The most common zinc mineral, usually found associated with galena (lead sulphide, PbS), it occurs in hydrothermal vein deposits, contact metamorphic zones and high temperature replacement deposits. Important deposits are in the Mississippi River Valley and in Canada, Mexico, Spain and Russia.

          • Zuiderzee

            The Zuiderzee (/ˌzaɪdər ˈzeɪ/; Dutch: Zuiderzee, Dutch: [ˌzœy̆dərˈzeː]; old spelling Zuyderzee) was a shallow bay of the North Sea in the northwest of the Netherlands, extending about 100 km (60 miles) inland and at most 50 km (30 miles) wide, with an overall depth of about 4 to 5 metres (13–16 feet) and a coastline of about 300 km (200 miles). It covered 5,000 km2 (1,900 sq mi). Its name means “southern sea” in Dutch, indicating that the origin of the name can be found in Friesland to the north of the Zuiderzee (also see North Sea). In the 20th century the majority of the Zuiderzee was closed off from the North Sea (leaving the mouth of the inlet to become part of the Wadden Sea) and the salt water inlet changed into a fresh water lake called the IJsselmeer (IJssel Lake) after the river that drains into it, and by means of drainage and polders, an area of some 1,500 km2 (580 sq mi) was reclaimed as land.

            Source: Wiki.

  20. First time poster but I read online the Captain of the Atlantic Explorer, currently sailing the Las Calmas sea said magnetism values are very high. High magnetism would suggest to me a high metal content. I no nothing about volcanos so really just sounding off. Is a high value of magnetism significant factor in what type of eruption there would be if there was an eruption or is it common to see magnetism in volcanos ? Ignorant in Canada

    • Java Sea?

      & going off on another tangent@ cafetite.

      “Cafetite is a rare titanium oxide mineral with formula (Ca,Mg)(Fe,Al)2Ti4O12·4(H2O)). It was first described in 1959 for an occurrence in the Afrikanda Massif, Afrikanda, Kola Peninsula, Murmanskaja Oblast’, Northern Region, Russia.[1][2] It is also reported from the Khibiny and Kovdor massifs of the Kola Peninsula and from Meagher County, Montana, USA.[1] It occurs in pegmatites in a pyroxenite intrusion as crystals in miarolitic cavities. It occurs associated with ilmenite, titaniferous magnetite, titanite, anatase, perovskite, baddeleyite, phlogopite, clinochlore and kassite.[2”] Source: Wiki.

      • Or teallite:

        “Teallite is a sulfide mineral of tin and lead with chemical formula: PbSnS2. It occurs in hydrothermal veins and is sometimes mined as an ore of tin. Teallite forms soft silvery grey mica-like plates and crystallizes in the orthorhombic system. The Mohs hardness is 1.5 to 2 and the specific gravity is 6.4. Teallite was first described in 1904 from its type locality in Santa Rosa, Antequera, Bolivia. It was named for the British geologist Jethro Justinian Harris Teall (1849-1924).” Source: Wiki.

  21. How about the black sea? Not sure what that has to do with apples though? This is too hard for a Friday night!

  22. Ladies and Gentlemen ….. Do we all love the Olympics…Yeah (not me) Thank goodness for Danny Boyle, he gave us all something to b*tch about. Wait for tomorrows press. Sorry, that was a bit OT but the riddle is too taxing tonight. Danny picked some good music though…Bowie and Floyd amongst others.

    • It was quirky and very British. I am not sure the rest of the world would have grasped the thinking behind some of the activities. I must admit I think Her Majesty and James Bond would certainly have been understood . But for me, the Royal corgis stole the show!
      It was a very spectacular performance and I am glad I didn’t have the responsibility of creating and staging it.
      It was a very long night.

  23. Good morning, Evening and G’day all
    Well the Olympics have started , a somewhat strange opening show but I think it sent many messages to the world. The idea that investment into and the acknowledgement of the next generation, not just of athletes, is important worldwide. It is a message I welcome and is dear to my heart.
    As we welcome the world to our country, I felt honoured that this Team Czech Republic had been briefed on our culture and like good ambassadors and scouts they came prepared, and also brought a smile to many faces with their Olympic outfits…….
    Not Armani, Dior, Nike…….
    Nooooooooooo! They did us the honour of recognising our English (Not scottish or Welsh or Irish) national dress. 😀
    http://www.sbnation.com/london-olympics-2012/2012/7/27/3197660/czech-republic-boots-opening-ceremony-2012-olympics

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