This is a short notice. I think that eruption has started under the glacier in Bárðarbunga or maybe in the dyke area. I base this on the change in harmonic tremor that is now taking place. Please note that this has not yet been confirmed by Icelandic Met Office or by Rúv in Iceland at the moment. So this is unconfirmed reports from me at current time (01:13 UTC on 9-September-2014).
I am waiting more details on what is going on with the harmonic tremor.
Update: If this is an eruption then it is not a large one. The confirmation on if I am correct or not is going to take several hours. Unless a glacier flood starts soon. It is difficult to know at this time. The hard problem with volcanoes under the glacier is that nobody is sure what is going on under the glacier.
Update 2: The harmonic tremor is now dropping, or at least was doing so for a short period. Nothing has been confirmed so far if there was an eruption or not. I have seen the harmonic tremor on the following SIL stations starting 8/9.
Vonaskarð SIL station.
Grímsfjall SIL station.
If there was an eruption taking place. It was small one and its unlikely that it would have broken the glacier or started a major glacier flood.
Article updated at 02:14 UTC at 9-September-2014.
Article updated at 02:18 UTC at 9-September-2014.
Article updated at 11:15 UTC at 9-September-2014.
THANK YOU JON, GOOD WORK MY FRIEND.
Jon, do you think this could be a large central caldera eruption. If so, it would take about 4-5 days to breach the glacier, correct?
I don’t know. The tremor data is difficult to read at the moment. This might stop without ever breaking the glacier, if it has started to begin with. I am not sure what is going on at the moment.
If it’s a large caldera failure, it would breach immediately, destroy the cameras and Jon would hear it in an hour or so.
A full-on caldera blast from something this size would be one of the bigger volcanic events in recorded history. The mechanics are unprecedented (huge glacier) but the physics are…dangerous.
agreed,. if the calderea colapses, we will see something simmilar to pinatubo in size. Now, there is no indication at the moment that this will happen at this moment, but the danger of it is real and if/when it happens we will see and hear it believe me. that explotion will be huge.
Now, to something else, the bårdarcamera, shows lots of instability in the atmosphere today, and lots of small EF0 twisters popsup all the time. quite neat to see 🙂 so if here is people never seen tornado formation check the cameras,its quite impressive
Thank you Jon Frimann for your dedicated, honest and timely objective reports on what’s happening at Bardarbunga. I would also like to express my concerns for Icelanders in general, that the whole island population should prepare a Plan B evacuation plan in the event that the eruption is larger than one expects or wants to take place. Is someone organizing a Plan B? Looks like all you need is some volunteer ships to be on call, and agree to go somewhere like a hillside in Norway?
Thanks Jon. I can see the tremor on your webicorders. But not on the graphs near Bardarbunga.
There is wind on my geophones. The different tremor can be seen on this two SIL stations.
http://hraun.vedur.is/ja/oroi/von.gif
http://hraun.vedur.is/ja/oroi/grf.gif
If this is an eruption, it is a small one at the moment. Since the effects are not big in the harmonic tremor plots.
http://geofon.gfz-potsdam.de/eqinfo/event.php?id=gfz2014rqrm
5.0 QUAKE
USGS: http://earthquake.usgs.gov/earthquakes/eventpage/usb000sal7#summary
5.4 118km WNW of Hofn, Iceland
Here it is.
http://hraun.vedur.is/ja/vatnajokulsvoktun/grf_trem.html
That might just be the magnitude 5,4 earthquake (USGS data) that just took place. We have to wait a little to see it clearly what is going on. This might take hours to become clear.
Jon, the quakes are increasing, could be getting close.
Will the eruption happen tonight or will it take several days?
Hard to say. We don’t even know if an eruption has started.
The eruption has started I think. I am not sure since this would be under the glacier. How long it is going to last I don’t know (if it is taking place). Based on the glacier thickness I would say several days are needed to melt the glacier to start visible eruption on the surface. If this eruption is taking place to start with.
Whatever the case, we are sure to know in next several hours to days if I am correct or not on this.
I have updated the article a little.
Its happening now,so is the ongoing eruption considered,separate from a caldera centered eruption
For the non-scientists under us: how do you recognize harmonic tremor on the graphs, Jon? Curious to hear!
It is going up from the levels it has been on. There are no background levels at the moment on many of the SIL stations around Bárðarbunga. This might be wind due to bad weather, but I don’t think that is the source since it needs to be at storm levels to do so.
This might be water, it can create harmonic tremor that looks like a harmonic tremor from a volcanic eruption. This might also be a minor volcanic eruption taking place. The problem is that I don’t have any way to know this until they do a visual check in next few days (or when they do them). Then it gets confirmed or not confirmed. So I might still be wrong about this.
Hello! First post, and an extreme amateur…
As TvS asks, on the graphs where harmonic tremors show, how do you see them? Where on the actual graph do they show…what do they look like?
Thank you
DID ANYONE JUST SEE THAT BIG CLOUD RISE WHERE R2D2 IS???
Please, do not use caps when writing a comment. It is rude and is equal to shouting in person. We don’t talk like that, we also don’t write like that.
Thanks.
I am so sorry for that. I didn’t mean to be rude. Will never happen again, I promise. Good-bye
I wouldn’t even say you was being rude Kim, more over excited and just used caps. No big issue really!
I believe it is also rude to ignore a valid question, no matter how grammatically incorrect. If your goal is correctness that is.
Dont feel too bad. I cap words here and there for EMphasis. 🙂 😉
Hi folks,
Here is the link to the new PNAS article on Mantle Updrafts and Oceanic Volcanism … open access.
http://www.pnas.org/content/early/2014/09/05/1410229111.full.pdf+html
Hey Jon.
I agree that there is a good chance that this is the start of an eruption, but I would guesstimate that this is hydrothermal in nature right now given that the caldera floor has been sinking as opposed to magma pushing its way towards the surface.
If watching Mila camera 1. What area would I focus on more if there is an eruption. If the camera is looking at the eruption area.. And jon could you pinpoint me to where I can register at. Thanks
If it’s to be a dike eruption, I’d watch between r2d2 and the fissure, in the dark gray area in the back with whitish streaks — that’s the edge of the glacier. There have been some big quakes around there in recent hours. Put another way, follow the line made by the river that comes off r2d2 to the right, and over to the glacier. Or yet another way: remember where the southern fissure was, before it went out again? Make a line between that and the main fissure, back towards the glacier and mountain. It might not be visible as an eruption before some or all of the rivers suddenly get fatter.
If the main caldera — I need help with that one too. Way off in the distance is all I know, beyond the clouds — maybe between r2 and the fissure also? It might burn through the clouds if it’s big enough, but as Jon’s been saying, so far, it probably isn’t.
Look for Meta here – on the right side you shd see register
http://icelandgeology.net
The moonlight on Cam 1 is magical this evening.
Geologically ,is there an apparent weak spot on the volcano that would cause concern such as old rifts or faults of a previous event presenting a point of least resistance
Which of the 4 likely scenarios from the Iceland Met office seems likely now?
On Mila 1 it looks like daytime, which does’t make any sense considering the actual time. Mila 2 looks like night. Any idea what’s going on with 1?
what is happening in front of R2D2 on the B2 cam?
Some clear updraft and cloud formation?
Please volcano please wait until I get to England on Thursday
answered my own question .. looks like fissure eruption has extended further to the north in front of where the R2D2 cam is ….
No BT, that is steam, from the contact between the lava front and river water.
I really do appreciate the care you put into your writing and reports. Thank you for making it available to us.
I do think you are correct Jon, based on the harmonic deviations so far having subsequently been assigned to subglacial eruptions and cauldron formations.
There are a lot of people who don’t agree. We’ll see as they say.
I have been recording webcaptures of the mila cam since the 16th, and yesterday at 0721hrs (BST) I saw a cloud rise from the glacier to the right of the smoke column. That time frame would coincide with the start of the rise in harmonic tremor that you speak of.
It probably has nothing to do with it, but if a cauldron is later seen at this location it would be interesting. What I saw may have been ice particles kicked up.
There’s something dark rising out of the clouds up and to the left of r2. fwiw.
gone again — a trick of the light? not the nearby steam, to be clear, the distant cloud bank. but was probably nothing.
There again…
Maybe it’s closer … but very obvious whatever it is. Seems to be a condensation cloud of some kind.
aaand gone again. Well, fooled me for a second. Middle distance scud. grumble.
The steam in the middle of cam1 has moved to the left over the night. Is the stem coming from lava on the move over the river?
I see that too, there also seems to be a bit more standing water peeking over the edge of the hill, is the damming nearly complete already?
Silly question time again.
If there is a small eruption in the Caldera is that a good thing or a bad thing?
By good, I mean, does a small eruption now reduce the chance off a large eruption later? Or does it accelerate things by releasing more pressure and increasing the rate that the Caldera is dropping?
Or is it simply too early to tell?
It could go a lot of ways, but one of the major concerns is ice melt reaching the magma. A small eruption could open cracks and melt ice, leading to a more explosive eruption. A lot depends on relative quantities, even then.
This from Dr. Carl’s blog over at Volcano Cafe
quote : So, what will most likely happen at the caldera? For starters, it is normal for rapidly deflating large magma chambers to cause deflation caldera formations. Normally this does not lead to an eruption, or lead to just small eruptions since a deflating caldera floor is a sign of loss of pressure.
In this case we need to take into account that there are two large pools of water below the ice over the caldera floor, and that the ice in and of itself can rapidly transform into water. If that water finds a way down into the extremely hot magma reservoir the water will instantly transform into supercritical steam and a steam explosion will occur. In that case pure physics take over; if a small amount of water hits a small area of hot material a fairly benign explosive event happens. If a large amount of water hits a small area of hot material a prolonged event follows. If a small amount of water hits a large area of hot material a short rapid explosive event happens. And if a large amount of water finds a large area of warm material I would prefer to be more than 50 kilometers away. : unquote.
Hopefully the last scenario does not occur.
The I.M.O is not ruling out any possibility.
Lots of “what next?” type questions, but no one can really answer as an event like this has not been witnessed before. There is no set path this will take. It will do what it does, when it does it.
Exactly, and how lucky are we to able to watch it from our homes thousands of miles away?
Quite right Andy, lots of its and buts, this is uncharted territory that we are in and Big B is playing a guessing game, anything could happen, probably the whole area is unstable. So give it for the scientist who risk it all in the name of research.
Is it my imagination or is the main plume getting darker now if it is please could someone explain why.
Thanks.
Imagination. Every morning and evening as the sun rises and sets someone says this. It’s to do with the angle of the light heating the steam / gas plume.
Exactly the same happens with rain clouds (which is what this essentially is).
Could this have some relation to Herðubreið and the eartquake swarm that is taking place there?
Imo is fully concentrated on another area.
Map posted on Dave McGarvie’s twitter that shows the earthquake locations nicely, and the most likely place where the possible eruption is occurring
https://maps.google.com/?q=http:%2F%2Fhraun.steinar.is%2Fquakes%2Fkml&ll=64.809804,-16.728058&spn=0.200193,0.727158&t=h&z=11
The last comment of Dr.Carl narrative,
Quote : I would prefer to be more than 50 kilometers away : unquote.
The lateral blast from Mt St. Helens 1981 caused destruction 19 miles away (30 kilometers)
Personally I would rather be more than 50 k’s from Bárðarbunga
Today I am roughly 150 km away and will be crossing the Þjórsárhraun lava flow, apparently the largest on earth. I remain somewhat concerned about the alternate scenarios for a glacial flood. Send out a smoke signal, will you, if that happens? I’m about to go offline en route to Jökulsárlón, the glacial lake to the south.
Wow: https://twitter.com/uni_iceland/status/509255724619542528/photo/1
visible @ mila cam : some clouds are rising at beginning of the glacier in direction 20m right from r2d2. Not too much, but visible.
Just ordinary clouds and light making this together.
Lol, I love the way it has become R2D2! Cam2 is great at the moment.
I’m having a terrible time getting onto the cams. Sporadic isn’t even close in description! Bummer.
Hi Jon, I’ll get straight to the point. I have been following your site since 2010, you often have difficulties with computer equipment and I have a lot of bits and pieces which may be of use to you.
A couple of older style eide discs,a couple of motherboards,if you are interested,then I can send you a detailed list. You can pick what you want and I will mail them to you.
If they are not to your liking then you can ebay them and hopefully gain some cash that way. Keep up the good work.
Can someone translate this? http://www.ruv.is/frett/thridji-sigketillinn-sest-i-dyngjujokli
Another caldera seen in Dyngjujökli , directly above where the dynamic corridor runs from the north to the volcano Bárðarbunga methods in blowout lava . This caldera was seen in exploration geoscientists flight yesterday , and two to three kilometers from the edge of the glacier . It is not yet clear how big he is.
Two other boilers have shown up in the Dyngjujökli , one of ten miles from the edge of the glacier and the other about six miles inside the glacier .
The latter was evaluated for three days about thirty -five feet deep and has been deepening . It is believed the short and ephemeral eruption under the glacier has prevented these boilers have been formed .
Pictured below is the first sigketillinn seen in Dyngjujökli , about ten miles from the edge of the glacier .
Cauldron, not caldera — “caldera” is a huge crater in the Earth’s crust where magma can flow, with a lid that can collapse, sometimes as is the case in Yellowstone tens of miles across. “Cauldron” is a depression in a glacier indicating melting from a subglacial eruption is happening below, generally much smaller in size. I have a photo of one as my desktop background now, they can be quite beautiful.
Thanks though!
For reference
http://www.ruv.is/frett/third-cauldron-spotted-in-dyngjujokull
http://www.ruv.is/volcano has posts in english.
Jay
A good test of how to use frontal lobe logical thinking rather than our more primitive (meaning fundamental) limbic system emotional thinking. Lets get more facts, difficult considering everything is deep underground and nearly one km of ice. All we have is sound, gps and samples of lava and gas. Perhaps by letting off controlled explosions a tomographical sound map of chambers and dykes could be madd. Could doppler shift tell us the lateral direction of underground magma flow ? Is the a technique for measuring vertcal flow ? Harmonic tremor is prolonged and so should be easy to distinguish from wind gusts but flow of water or magma ? This whole subject is so complex. My only advice is dont be preoccupied with speculation and make sure you all get a decent nights sleep 🙂
Has Cam 2 changed position since 2 days ago?
Cam 2 – The steam is not going right or left – no wind?
Cam 1 – Last nite I saw R2D2s friend next to him, and later I saw his friend leave, VERY bright headlights!
I see puffs of steam below blowing to my right.
I look fullscreen once in awhile – AWESOME! One day earlier I thot I saw something small and pale colored scurring near R2 on cam 1. Didnt it get the memo?
Decided to view both cams before posting. Shaking again.
Cam 1 – steam appears to drift both right and left … errr?
Cam 2 – Huge steam column drift left, lesser steam behind drifting right.
Shaking
Looking for video of this eruption with sound for one of you, I ran across this.
This may – or may not – be in the near future for Bardabunga? 😮
Iceland’s ‘Pompeii’ emerging from the ash
http://www.bbc.com/news/magazine-29045900
For English I go to then click English
http://www.ruv.is
5.2 Sep 9 – 01:07:31.5 UTC
http://www.emsc-csem.org/Earthquake/earthquake.php?id=399064
John Seach volcano breaking news, tweets
http://www.volcanolive.com/news.html
John Seach volcanoes of Iceland
http://www.volcanolive.com/iceland.html
Winds mainly southwesterly over Iceland this week. A ridge for Saturday.
Personal experience with a volcano. In May 1980 was over 200 miles to N and slightly W of Mt. St Helens.When the mountain erupted with an explosive blast, it shook the house like a plane had hit us, windows cracked, house shuddered. In the first hours..we did not know what happened as we lived on a farm in the country, TV was not cable then. We thought a nuclear war might have started. Then the news came on..then a fine dust started filtering down..it was greywhite and like glass shards when you rubbed between your fingers. Cars with volcanic dust had to be washed off with water spray, rubbing took off paint. Some people wore masks..the dust came inside a little. No one told us the dust might not be good for lungs, even a little made us cough. And this was over 200 miles away from the direction of most of the ash clouds. So 50 KM might not be far enough, these are tremendous acts of nature we can not control or predict. Jon, you are doing a wonderful job on this site. Have great respect for your work.
Take care with any ash – I have scratch marks on the car windows from the 2010 ash cloud, I did not know until later the ash could damage surfaces and had used a hand held ruber blade to clear it away with the morning dew.
I have updated the article.
Can someone kindly give some links to the thickness of the caldera lid that is floating on the magma at bardurbarda?
Thanks
Andrew
I don’t think it is known. At least I have not seen any number of the crust thickness in the caldera.
Thanks, are you able to give me your best estimate please?
When you consider caldera subsidence what amount of material is subsiding including ice that is above the magma?
Speculation will be fine.
Thanks
Andrew
This is a model by Ekström, cited by volcanologist Haraldur Sigurdsson in his blog. Could perhaps help a bit.
http://vulkan.blog.is/blog/vulkan/entry/1428340/
Thanks!
I am particularly interested in what would be the minimum thickness of “the crust” of the caldera.
Additionally, I understand there is usually solid ice in the caldera bottom, is that correct?
I think i read it would be water in the bottom and ice on top and this is what could be causing the subsidence. Am sure I read that they were dropping some GPS instruments to measure this a couple of days ago so we may soon see some results or updates.
I think if there is solid ice or water at the bottom of the caldera would depend on the heat. There could always be sort of a small “water balloon” there, because of a high temperature (geothermal) system which is normally to be found at active central volcanoes.
See eg. http://www.norvol.hi.is/pdf/HB2003GlobPlanCh.pdf
I’m pretty sure ice penetrating radar indicated there was a sizeable lake in the caldera.
I have to say that I have developed a total fascination and respect for volcanoes due to this brilliant site. However having the holiday of a lifetime booked this coming Saturday from Manchester UK to California, I have mixed emotions right now.
I was born in Manchester but now live in CA. It’s a good transition!
Several tornados on cam1 now!
http://i58.tinypic.com/2e2nxbo.jpg
They’re not true tornadoes, but might be classed as land spouts, since they form from the ground up not cloud down. Still, amazing.
Hi Can somebody help me with a better translation of this please?
http://vulkan.blog.is/blog/vulkan/entry/1440799/
Nei, efnasamsetning kvikunnar sýnir að það er ekki megingangur, sem kemur úr möttli, heldur gangur út úr kvikuþrónni undir Bárðarbungu. Stóru skjálftarnir, sem enn halda áfram, eru vegna þess að askjan er að síga, þ.e. þakið á kvikuþrónni sígur niður vegna þess að kvikan streymir út í ganginn. íshellan hja´lpar til, en öskjulokið er nokkrir km á þykkt og þarf ekki ísinn til.
Which google gives as
No, the chemical composition of the magma shows that it is not the primary operation, which comes from Mat, but walk out of the magma chamber under Bárðarbunga. Big earthquakes, which still continues, is because the blank is lowered, ie roof of the magma chamber slides down because magma flows out into the corridor. The ice slab hja’lpar, but box cover is several meters thick and does not ice.
Thanks Andrew
my giggle translation of the blog.
Scientists get much information about the origin of the magma and the internal composition of volcanoes by chemical analyzes of lava and other volcanic material, just as the doctor collects a variety of fluids (blood, urine, etc..) from the patient and analyzed to determine the internal condition. Now the Institute of Earth Sciences, University of Iceland published analyzes of five samples of lava from the new blowout lava. It is shown in the table above. There are two ingredients that tell important stories. One is silica (SiO2), which is about 50 to 50, 8% of the swarm loved. thing is magnesium oxide (MgO), which is about 6.8 to 7.1%. This is the chemical composition of basaltic magma, which has served in a shallow magma chamber inside the earth’s crust for quite a while and evolved. This is not a chemical primitive magma, which comes directly from the earth’s mantle, of great depth. Thereby theory some scientists dead, walking has come directly from the mantle. crust ca. 30 to 40 km thick in this area and there under the mantle, which is 2900 km thick. primary magma formed in the mantle and fight in the Earth’s crust, where it evolved. Which is the chemical composition of the magma in the mantle? second picture is taken from Kresten Breddam and shows examples of the composition of magma that comes directly from the mantle. This example is basalt, which erupted to form buttes Kistufell, which is just north of Bárðarbunga. basalt in Kistufell is unusually rich in magnesium, and MgO in glass (volatile session) ranged 10 to 12%. Currently Breddam demonstrates this chemical pulp (blue one box pictured below), which is in chemical equilibrium with the robe and has come directly from the mantle. This is a dramatically different dynamic session, currently erupts (red circle the figure) and she clearly did not come directly from the mantle. However, primitive magma, such as the one formed Kistufell, received up from the mantle, accumulate in the magma chamber and changed over time in advanced raw, like them, now erupts . This is shown by the red dashed line in the figure. these compositional information supporting the following simple model of Bárðarbunga: (1) Primitive magma (MgO 10 to 12%) flows up the mantle and fills a magma chamber shallow in the crust below the box Bárðarbunga. Such feed is probably always active and does perhaps without any mark on the surface. (2) converts the primitive magma composition for differentiation when certain crystals are separated by a swarm loved. This has dynamically developed and MgO decreases to approximately 6 to 7%. Perhaps the magma chamber then lagskift, with a layer of advanced dynamic on top of the primitive, which comes up from the mantle. (3) Fluid pressure in the shallow magma chamber is increasing and advanced dynamic breaks out of the development, in the fissure system, first to the east and then north and forms the margumtalaða dynamic motion. (4) Sprungugos begins where the corridor intersects the surface of the earth north of the glacier. (5) The flow of magma from the magma chamber to the corridor and the surface causes a pressure drop inside the magma chamber and roof it, or the bottom of the carton starts to slide. now amounts to up to 15 meters. Today, the lava reached 19 square kilometers in area. Probably the magma chamber full when seismicity began. eruption started with a full tank. It can easily contain dozens if not hundreds of cubic kilometers dynamic, but probably will never amount to a small fraction of this magma to the surface.
Sorry delete that, its a translation of the reply and not the blog I get the same as Andrew,, Giggle on me!
I wish I could. But due to how comments in WordPress works I cannot due so since there are replays below your comment.
now it is clear to me what the first part of that quote means. stuff in the dyke has come from the shallow magma chamber. The bit i am particulary interested in is what is a few meters thick. Elsewhere on his blog he is suggesting 2-3kms is the thickness of the calderas crust between ice and magma as far as i can tell anyway.
And actually in the icelandic there is km. “en öskjulokið er nokkrir km á þykkt og þarf ekki ísinn til”
oddly Google manages to translate “km á þykkt” as km thick.
So the crust between the magma and ice is estimated to be 2-3km thick
If that is the case, there must be some serious melting taking place at the bottom of that 850 meter thick glacier.
From reading the model of the volcano on Harolds blog provided earlier in reply to me, it seems harold is saying the ice,the crust, and the magma chamber and the surrounding structures are all moving down and this why there are such very large and frequent eqs. he has another post about that on his blog
“what caused the very large earthquake”
http://vulkan.blog.is/blog/vulkan/entry/1433529/
..”the lock of the caldera is some km thick”
He says anyways that the chemistry of the eruption products (and Haraldur Sigurdsson is a geochemist http://en.wikipedia.org/wiki/Haraldur_Sigurdsson ) tells us that the magma is not coming from the mantle, but from a magma reservoir in Bárdarbunga.
Just a quick idea, could it be, that the top of bardarbunga caldera is sinking due to melted ice on the bottom? By the way, is there any new info on the Grimsvötn water level?
I did some rough calculation to see how the effect and cause would balance.
Assumed story would be like this:
6% of the ice within bardarbunga caldera was molten of which 2% were released to Grimsvötn. This would result in a 20 m decrease of bardarbunga top level and 24 m increase of grimsvötn water level (last info was 6 m I think 10 days ago?!)
assumtions below.
Diameter Bardarbunga 10 m
Area 78.53981634 m²
Ice Thickness 800 m
Volume (Ice state) 62831.85307 m³
Weight 57585393.34 t
Water Density (3,98 °C) 1000 kg/m³
Ice Density 916.5 kg/m³
Percent Ice 94%
Percent Water 6%
Outflow percent of water 2%
Ice 94% Water 4% Thickness 780
Grimsvötn Area 48 km²
Grimsvötn see level increase (intake of 2% from bardarbunga) 24 m
ps.: just because playing around with data is so much fun ; )
Sorry, Units were not correct:
Diameter Bardarbunga 10000 m
Area 78539816.34 m²
Ice Thickness 800 m
Volume (Ice state) 62831853072 m³
Weight 5.75854E+13 t
Water Density (3,98 °C) 1000 kg/m³
Ice Density 916.5 kg/m³
Percent Ice 94%
Percent Water 6%
Outflow percent of water 2%
Ice 94% Water 4% Thickness 780
Grimsvötn Area 48000000 km²
Grimsvötn see level increase (intake of 2% from bardarbunga) 24 m
Jón, this might has been asked before, but after reading large sections of your posts and comments, I am still not sure about the causation in this event.
As I understand it, the current eruption is fed from the magma chamber of Bárðarbunga, as evidenced by the trace of earthquakes generated by the intruding magma, the displacements measured by GPS and the deflation of Bárðarbunga caldera corresponding to the ejected magma volume. But what is the primary cause? Did the magma press apart the rock leading to the formation of a dike or did it happen vice versa: tectonic rifting opened fissures which allowed intrusion of magma tapping the magma chamber, which then more or less passively empties into the Holohraun plains? What is cause, what is effect?
The path the magma took was the path of least resistance in the crust. It did drill it self out of the magma chamber (based on earthquake data) and that took some 13 weeks, starting in week 20 as can be seen here.
http://hraun.vedur.is/ja/viku/2014/vika_20/index.html#mark
Why the magma didn’t break forward were the most earthquake activity was at the time I do not know. But it is also important to remember that there are two dykes in this equations. Currently the second one is quiet, that dyke is located directly north of Bárðarbunga volcano, close to Vonaskarð SIL station.
thanks, that must be impressive pressures that push apart solid masses of rock. Did anyone attempt to estimate the actual pressure in such a magma chamber?
Forgive me if someone has already posted this link. It’s very cool!
http://baering.github.io/earthquakes/visualization.html