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.
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.
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.
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.
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.
593 thoughts on “The (ash) history of Iceland, in my backyard – Part I”
I pursue your comments already for a long time with big(great) interest, because I am crazy a little volcano, but still beginner – however, I would like to learn, and I believe, there I have big(great) chances in this
miraculous forum at high level,
I also have immediately a question
the left picture on this live cam – is the Askja?
I find the upper precipitously dropping(falling off) edge of the glacier edge interesting in which for 3 weeks more and more layers(shifts) are to be seen
Maybe this will help
uiii … many thanks to You 🙂
The 500th Comment.
Adamite: Adamite is a zinc arsenate hydroxide mineral, Zn2AsO4OH. It is a mineral that typically occurs in the oxidized or weathered zone above zinc ore occurrences. Adam is an apple cultivar.
Topaz: Topaz is a silicate mineral of aluminium and fluorine with the chemical formula Al2SiO4(F,OH)2. Topaz is commonly associated with silicic igneous rocks of the granite and rhyolite type. It typically crystallizes in granitic pegmatites or in vapor cavities in rhyolite lava flows like those at Topaz Mountain in western Utah. It can be found with fluorite and cassiterite in various areas including the Ural and Ilmen mountains of Russia, in Afghanistan, Sri Lanka, Czech Republic, Germany, Norway, Pakistan, Italy, Sweden, Japan, Brazil, Mexico; Flinders Island, Australia; Nigeria and the United States. Topaz is also an apple cultivar but can’t see a link to water on this one.
Source for both: Wiki.
Gravenstein is another apple cultivar. Graven or graben is the result of a block of land being downthrown producing a valley with a distinct scarp on each side. Graben often occur side-by-side with horsts. Horst and graben structures are indicative of tensional forces and crustal stretching. But it doesn’t need water …..
Or it i simply absolutely not volcano related and the answer is Apple Pie 😉
Anyway, a monster page just found its way over to VC. But dont check it out if you have a slow computer and dont even try from a smartphone. https://volcanocafe.wordpress.com/sheepy-dalek-name-that-lava-answers/
It is to be found under Gems in the menu.
At the moment it is just a list of the images used, the answers and the winners. We could pace additional info on the volcanoes there.. for this you could maybe help me finding it.
Because i am not really feeling well and have to finish my SEM pages and wanted to create a page for the best plots by Lurk, dfmorvn, Chryphia and KarenZ. Again i would love coments helping me so i dont have to read the whole blog again.
Sorry, you are not feeling well. Hope you feel better soon.
Let me now which plots you want to use of mine so I can tidy them up if needed.
I wanted to have some in the gems section, but not all because loading takes too long if we use all. So just point the best out, and it would be cool if they are not on tinypic but maybe youetube or other sites where they can still be found in some time.
On those “plots by Lurk”, you might want to pull down a local copy. I don’t know how long TinyPic holds the image active. That will protect the page and references from breaking whenever TinyPic deletes the image.
I am starting to think we should make it possible for you to upload things yourself.
Does anyone know if Carl is and or Alan will stop by today?
I will prepare Ursulas name that lava riddle just in case. Shall i?
Nice, Spica, if you have the time. But only if you feel OK. Take care of yourself!
The guys did not tell whether they would drop in or not, I believe. But Alan probably had a party last night so he might need to recuperate a little today.
I am not here, any rumours of me being here is greatly exaggerated.
Post will be coming.
So good to see you.
Who me? I am not here…
And there is absolutely no eruption happening at Thingmuli Volcano.
Apples, apple juice, apple pie – even Adam and Eve crossed my mind. But one word that returns over and over again is cider. It just cannot be cider (“I am not”) but it can be sider.
So here we go again: deep water siderite (still think it is a mineral!).
“In the modern environment siderite is precipitated around CO2-spring vents. In contrast, siderite from the Pleistocene/Holocene boundary occurs as small layers in a varved sequence. The stable isotope data provide strong evidence for an analogous formation of both types of siderite. The different CO2 sources of the siderites allow reconstruction of a distinct rise of productivity at the Pleistocene/Holocene transition.” Source: http://sp.lyellcollection.org/content/40/1/153
“Deep water of Lake Nyos is known to be saturated with siderite (FeCO3). The
siderite may be formed as a result of interaction between monzonite and CO2-rich fluid.”
So – I am (deep water) Siderite and I’m found in CO2-rich fluid.
Tee Hee –
You have the first 5 letters correct, only 7 to go 👿 !!
It’s a rock type……..
There is a sideronatrite which is yellow http://webmineral.com/data/Sideronatrite.shtml
1st 6 now 🙂
A Siderophylitte also exists 😉
And that would be a sodium iron sulphate with water.
This was the question
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?
Too many letters! See 14.51 😉
Siderophylitte belongs to the Mica group ( Mica is Glimmer in english right?
Sideromelane it is.
“Sideromelane is a vitreous basaltic volcanic glass, usually occurring in palagonite tuff, for which it is characteristic. It is a less common form of tachylite, with which it usually occurs together; however it lacks the iron oxide crystals dispersed in the glass, and therefore appearing transparent and pure, with yellow-brown color, instead of tachylite opaque black. It forms at higher temperatures and with more rapid chilling. Presence of sideromelane indicates higher temperature of the lava, and solidifying of the flow closer to the vent, probably by rapid quenching in a wet environment.”
This is also very important, same source:
“Sideromelane often forms during explosions of submarine volcanoes and subglacial volcanoes, and often occurs as fragments embedded in a palagonite matrix, forming hyaloclastite deposits. Sideromelane is a mafic rock.“
Conclusion: I am Sideromelane, a vitreous basaltic volcanic glass, usually found in palagonite tuff, often together with (opaque black) tachylite.
That took some time!!! 🙂 Sideromelane ’tis
Did y’ like it?
Sider (Cider) melos = dark
You folk may have to remember your classics 🙂
Sissel may now sleep tonight!
How many points Alan? Hard to find an image. I am updating the answers to your riddles. Dont know if you have seen that page?
Hey you really deserve that cause you worked hard for it. 🙂
Hi Alan, It was very nice! Cider I knew but melos not. Never thought to find the solution. How do you manage to make them!!
A good nights sleep ahead.
You make them by firstly knowing the mineral/rock/fossil etc, then finding cryptic clues to give the name via classical/english variants!
Keeps me busy thinking how to word ’em yet be ‘fairly’ obvious once ‘got’!!
2 points ‘cos 2 parts to the answer!
Well done, not too easy!
Siderolites? ‘A meteorite consisting of a mixture of iron nickel and ferromagnesian minerals as olivine and pyroxene.’
I’m thinking ‘cider’ and ‘0 lights’ in case thise seems a weird choice! 🙂
Noticed from and Eruptions Post….
Ruapehu’s drum got a bit festive recently.
Maybe we should keep an eye on this seismometer. Thanks Lurking
Based on GVP, is usually makes a VEI 1 or 2.
The last VEI 4 was 7840 BC.
An unknown volume (according to GVP) was erupted in ≈9850 and is indicated by the UT1 and UT2 Tephra.
The paper at http://tinyurl.com/cpyagqn places these layers as part of the “PM” eruption sequence. Tallying up the volumes gives 5.9 x 10^9 m³of tephra ( 5.9 km³ ) and from 0.1 to 0.3 km³ of magma. (VEI 5)
It appears that the PM sequence was when multiple vents got into play… all the way from Ruapehu to Taupo.
That would not have been fun. From what I understand, there is a hiking trail through there, sort of like Fimmvörðuháls.
Event of long period seismic station MACI of IGN, (Tenerife). It can be seen as the sound produced, (accelerated about 100 times), it is similar to that produced by a body. A harmonic tube of magmatic ducts, which resonates to the passage of the volcanic fluids (liquids or gases)
I’ll mail a couple of riddles as will be away for at least 2 weeks! 🙂
See ya, Gang, have fun!!
Have fun too. Happy holiday.
Belated Happy Birthday to you!
And have a lovely holiday too.
Have a great time!
Magnitude mb 5.0 Region SOUTHERN ALASKA Date time 2012-07-28 19:01:02.0 UTC
Location 59.62 N ; 152.70 W Depth 10 km
“Campi Flegrei Deep Drilling Project”
Drilling at Campi Flegrei has already started. It is now at 200 m deep. Their goal is to study the ‘supervolcano’ in depth and evaluate the risk of an eruption (very remote) and mitigation measures.
The first attempt will reach 500 m and there will be a second borehole at 3000 m.
INGV is taking part too.
http://www.ansa.it/web/notizie/specializzati/scienza/2012/07/26/Iniziata-perforazione-supervulcano-Campi-Flegrei_7240605.html (in Italian)
Cheers Renato! As this is highly interesting, I’ve taken the liberty of posting the Gaggle translation for those of us not conversant in Italian:
It ‘started drilling the Phlegrean Fields, which will allow for the first time to observe from a supervolcano. There are only a dozen volcanoes in the world as these are structures capable of very violent eruptions, but fortunately very rare. The drilling has reached around 200 meters deep and is the result of an international project ‘Campi Flegrei Deep Drilling Project” led by the Italian National Institute of Geology and Volcanology (INGV).
” The drilling and ‘started a few days in the area of Bagnoli Futura”, said project coordinator, Giuseppe De Natale, the Vesuvius Observatory of INGV. The goal, he explained, ”’ monitor and study this volcano to mitigate the risk.” This is to fully understand how and ‘done and how a supervolcano and allow drilling’ to make a ‘journey’ into the past of the Campi Flegrei supervolcano.
The drilling was originally scheduled in 2010, but then stop by the Town Council had blocked the project. The green light by the new administration and ‘arrived a few months ago. The goal, explained De Natale is’ monitor and study this volcano to mitigate the risk.”
The project is carried out by the international program ‘Campi Flegrei Deep Drilling Project’ and e ‘funded by the International Consortium for continental deep drilling. At this point, researchers are realizing the first well expected that the project will be ‘deep and 500 meters will have’ a cost of about 500,000 euros. ” We came – he said – to touch the yellow tuff ejected by the eruption of 15,000 years ago and we think has a thickness of about 100 meters.” After the first well of 500 feet, in about two years we expect to achieve a second well, 3,500 meters deep. It ‘s not the first time that the needle pierces the supervolcano of fields.
Flegrei: in the 70s and 80s, in full bradisism says De Natale, we were drilling by Agip and Enel also quite deep for geothermal purposes. They arrive ‘at 3,050 meters depth’, but the resources were not found with the criteria exploitable because of the time ‘is too big and also included central Italy at that time was focused on nuclear power. Most of the knowledge we have on the volcano of the Phlegrean Fields are due to those wells, but ‘had a different purpose, he added De Natale, and’ the first time instead of a perforation is made for scientific purposes,” to create an observatory in depth ‘studies that the volcano.”
I did not know there had been bore holes sunk in the 1970s and 80s.
Yes, close to Solfatara to experiment with geopower. They had an Icelandic fad for a while and got inspired by Kröfluvirkjun.
I am very excited about this, it is so good that more scientific heads have gotten into power and over-turned the old ruling. The old ruling was based on the concerns of a local “scientist”. In reallity that “scientist” was a witch-doctor with an ouijaboard. So because of holistic nut 4 million people was endangered.
6.6 – New Ireland Region,Papua New Guinia – 66.7 km
Congratulations, Sissell. Well done 🙂
A good read (on Icelandic hotspot):
“An Iceland hotspot saga” by Bjarnason, PDF available free.
Basically, he says that the Icelandic plume is centered right under Tungnafellsjokull (where curiously recent swarms have occured).
As it nears the crust, the plume radiates laterally. It is also shaped elongated mostly northwards and southwestwards. The plume also shows a kind of “plume head” structure as if it would approaching closer and broader near the crust towards the southwest direction, almost some 700km in that direction), and the the least under the Eastern side of Iceland. They also state it is hypothesized the plume might extent northwestwards but their models fail to confirm that.
Well, this explains so much. As I have often said, that the plume must divide somewhere at 100-50km deep towards the north and the southwest, feeding Askja, Krafla and Theistreykjarbunga in one side, and the region of dead zone, Katla, Torfajokull, Hekla and Eyjafjallajokull. But it spreads near the surface towards the southwest over a wider distance than towards the north, which explain the increased activity of Hengill and Reykjanes peninsula.
So, if we have pulses of hotspot activity, kind of a blob of magma pushing upwards then we must see increased activity in the several Icelandic at “same” time. Something which actually happens, within a pulse we observe very increased activity at both Reykjanes, Vatnajokull and Hekla/Katla within a time frame of about 30 years (between the 150 years). I think we are just in the early stages of one of these new pulses, which explain the increased activity in the southwest, the EQs in SISZ in 2000 and 2008 and the increased activity at Katla and Vatnajokull (and other volcanoes towards the north).
So this is the reason sometimes the whole Iceland lit up as a Christmas tree, after long durations of low seismic activity…. ?
**insert “why” between reason and sometimes… Let me try, So this is the reason why sometimes …ahh the grammar my friends…
Great food for thought!
This seems to be the latest report from the Atlantic Explorer as posted on the AvcanFacebook Page by Dioni Rodriguez.
Como un suplemento a mi ayer post a bordo del Atlantic Explorer hoy el equipo científico en uso. Vista actual de la Eldiscreto. Contrario a todos conjeturas el cono volcánico es ahora en parte deslizado o derrumbado los muros, es ubicado la parte superior de las Eldiscreto actualmente 84 metros bajo la superficie del mar. No 88 m pero ahora sólo 84 m. El capitán de la Atlantic Explorerme confirmó a petición reiterada. Entonces es lava introducido casi desapercibido en los últimos meses. Duda no puede ser por tanto una extinción total de la actividad volcánica desde marzo de 2012. Debe haber tan sobresalientes – si sólo pequeñas – canales de magma. A continuación en la foto, sólo la sonda es drenada. Los resultados estarán disponibles sólo Palmas durante el transcurso de la próxima semana después de exhaustiva investigación en el laboratorio de la Universidad de Las
,As a supplement to my yesterday post aboard the Atlantic Explorer today the scientific equipment in use. Current view of the Eldiscreto. Contrary to all conjectures the volcanic cone is now partly collapsed or sliding walls, is located the top of the Eldiscreto currently 84 meters beneath the surface of the sea. No 88 m but now only 84 m. The captain of the Atlantic Explorerme confirmed to repeated request. Then it is almost unnoticed entered lava in recent months. Doubt is not therefore a total extinction of the volcanic activity from March 2012. There must be so outstanding – if only small – magma channels. In the photo, below only the probe is drained. The results will be available only Palms during the course of the next week after exhaustive research in the laboratory of the University of the..
Comment: El Discreto is what we here call Bob. Manfred Betzwieser used to call it This obvisously others do too.
Thanks Spica for pointing this out.
Is it not intersting they have mentioned there must magma channels .
Yeah, but i have to read it more closely, was caught up in preparing possible posts do correction on the new page and falling appletrees.
This is interesting about activity inall the Canary Islands in 2010.
I have translated some parts .
,,However, the quarter has been accompanied by related surprises, such as the detection of volcanic tremor in the spectrograms of the NACC seismic station of the National Geographic Institute (IGN), located in the National Park of Teide (2). The registration occurs no fewer than nine days, specifically: 28, 29 and 30 November, as well as 5, 7, 8, 9, 16 and 17 December 2010.,,
,,Volcanic tremor is associated with the movement of magma or other fluids on the inside of duct and usually, but not always, as we shall see, precedes or accompanies volcanic eruptions.The first time that volcanic tremor was recorded on the island of Tenerife was during the unrest of 2004-05 (5). On that occasion, however, it came accompanied by a profusion of earthquakes of all kinds: volcanotectonicos long period events, hybrid (5); There were also increases in the diffuse emission of volcanic gases (6,7); variations in physicochemical parameters of aquifer (8); and gravimetric alterations (9). According to various publications on 04 unrest could be due to an injection of magma that was in the basement, followed by a migration of volcanic gases. The interaction of these gases with the hydrothermal system could be the cause of the tremor (5.9).,,
The full report which shows maps and graphs can be read on :
Does anyone happen to have a link to the Seismometer at Ruapehu Lurking pointed too yesterday? Pretty please… post it, Thank you.
i find the idea of Lurking becoming a dragon really brilliant.
I think the Dragon-messages would be rather interesting when editing is necessary… 🙂
Carl, there is a new draft i just uploaded if you want to use it. And we have a new page https://volcanocafe.wordpress.com/sheepy-dalek-name-that-lava-answers/ in Gems
Just saw the new Name the Lava page. Awesome!
I think I will try to write a part two of the lava chamber formation. But first a few cups of coffee more… 🙂
To all the providers of the images. I added thoe i could find to show the original, if any of you still got an original which is not sown on that page.. please send it to me or leave a comment. Steve and dfmrovan already did and i will include the comments and additional info about the volcanoes. But a short version, not a full text.
OT An huge appletree in my garden just toppled over. We had a bad storm last evening and i just checked, at least 3 other trees will have to be cut down.
That is so sad.
Here we are having tropical rains. I have never seen anything like it. It is 27 degrees celcius and it just floods down from the sky. For those of the more southern persuasion. Rain here is always cold and miserable, it is never ever 27C warm. I just went out in swiming trunks into the rain. Weird feeling. The ground is covered with steam as the rain starts to boil off the ground. I have seen this in Sumatra Strait, never here.
Sorry to hear you’ve lost some trees. I love apple trees and want one in my garden. First I have to get rid of the enormous Eucalyptus that a previous owner planted. Not really good for anything but firewood. Even the birds won’t nest in it (expect the pigeons). But I hate to cut down trees, especially useful ones.
Good morning, evening and G’day.
Today started with some excellent news. A young lady that I befriended via an African Safari live site told me that she has gained her degree (BA Hons) in Environmental Biology and Eductation.. She was very brave to overcome many difficulties and continue to pass with flying colours. She had left school and was working out of necessity but decided she wanted more from life.
In her first year she nearly gave up. The studying and writing was very difficult for her but with some shoving from me, really just boosting her confidence, she carried on. It’s a great feeling to know good things can come from a chance “meeting” on the wonder internet and I can still help the next generation of scientists.
OOOps….. I must write out 100 times…I must spell Education correctly! 😳
I worked for about ten years writing about music for a newspaper, mainly writing the classical concert reviews. Guess what word I can’t write? Yepp, that would be music. I for some unfathomable reason always write it Msuic. The editor in chief was a guy specialized in moivse… It is rather odd that the two words we wrote most often, was the two that we almost always succeeded in spelling wrong.
The swedish originals are “msuik” and “flim”.
Big congratulations to her and to you for successful mentoring!!! 😀
Last friday we had our waterpipe bursted, and a bit of lood on our fron yard, countys workers made a quick fix for it, but left the hole open for additonal work. Now last night we had three thunderstormfronts colliding pretty much above our house meaning heavy lightning(230 strikes/min peak and lot of rain so now we have a 3x5x2,5m swimming pool on our driveway 🙂
Now you just need to move the sauna next to it and you are good to go 🙂
Post would be ready, you could hit the publish button.
Ok i ll do it: New post will be up in a minute!
A riddle for the ladies ( and gents)
Spica – forgotten your new email address – quick please, leaving 1200!!
Have a nice trip Alan!
Sent one already today, to which email of yours?
Use the aec one, its ok.
I was asking for the answers to the riddles.
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