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lorenzo

Bárðarbunga and Askja - Volcanic Activity

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LOL a new vent opened up next to yesterdays...

post-4726-0-04659100-1409637763_thumb.jp

Edited by Rustynailer

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No big earthquakes since yesterday.

 

Nice to see the fissure eruption continuing though.

 

Karyo

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morning all,

 

I have to say I really am enjoying this thread. Been perched in here reading and learning :)

 

Found a great link this morning to some stunning pictures of the fissure eruption and had to share with you 

 

http://photos.gudmann.is/#!/index/G0000VHvgRsUlb5M

Yes they are great photos of the fissure eruption, thanks for posting the link!

Edited by lassie23

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Yes they are great photos of the fissure eruption, thanks for posting the link!

Img 14 - looks like a mini-tornado to the right ;)http://photos.gudmann.is/#!/index/G0000VHvgRsUlb5M/I0000vkYnJnNO8mc

Img 13 has a number of small vortices showing, heat induced no doubt. http://photos.gudmann.is/#!/index/G0000VHvgRsUlb5M/I0000EVwWHY3JDLQ

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Ah the first big quake of the day 4.7 

 

Tuesday
02.09.2014 11:26:50 64.679 -17.484 6.1 km 4.7 99.0 4.7 km NNE of Bárðarbunga

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Ah the first big quake of the day 4.7 

 

Tuesday

02.09.2014 11:26:50 64.679 -17.484 6.1 km 4.7 99.0 4.7 km NNE of Bárðarbunga

 

 

Followed by another

 

 

Tuesday

02.09.2014 13:55:01 64.621 -17.370 6.1 km 4.6 99.0 7.8 km ESE of Bárðarbunga

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 For this post I will start with some observations and leave all the wacky guess work to later.

 

First up the tremor graphs clearly show the eruption and it begining to decline somewhat. Thats the red lines on the following graph.

post-2809-0-41199300-1409670793_thumb.gi

 

Next up is the GPS measurements which the imo has kindly put up. The following is for the period from the 14th of August until now.

post-2809-0-65691600-1409670910_thumb.pn

 

You can clearly see the opening up of the fissure from the DYNC and GSIG movements. Thats almost 5 meters by my caluculations that the fissure has opened up.The only anomaly to the general movement appears to be the VONC GPS which appears to be moving south east when you might expect it to move northwards.  This I think might be related to decompession of the magma chamber, although some might suggest it is that part of the plate swivelling. Looking at the current GPS map for the last 3 days:

post-2809-0-91769100-1409671114_thumb.pn

The trends continue only somewhat slower. Incidently if you had looked at this graph a couple of days ago before the eruption you might have seen VONC GPS pointing somewhat in the opposite direction. This would perhaps suggest comrpession in the magma chamber before the eruption which has now fallen back into decompression. Some thing I think you can see on the following plot

post-2809-0-01592800-1409671296_thumb.pn

 

Interestingly the neighbouring volcano Grimsvotn which is nearer the GFUM GPS is showing slight uplift.

post-2809-0-45041600-1409671498_thumb.pn

 

In comparison to yesterday, more sulphur dioxide has been measured in the eruption cloud. The authorities are advising that it is essential that those working near the eruption site are equipped with gas sensors and gas masks. If you want to scare yourself silly then go read about volcanic gases at volcano cafe at the following link. I would suggest at the moment that only areas close to the eruption site are affected at the moment.

http://volcanocafe.wordpress.com/2014/09/01/volcanic-gases/

 

Ok so that is a quick round up of the activity (yes I know I have been a bit light on details of the eruption but others have covered that fairly well) now o to some guess work about what is going on beneath Bárðarbunga. The first question I ask myself is why does the fissure occur here and not closer to where the plate boundaries ought to be  (Red dots on the following map).

post-2809-0-32513400-1409672605_thumb.jp

Actually I think the clue is on the chart in that the thickness of the crust is different (possibly because of the mantle plume udner iceland as well). It has been argued that the crust in Iceland actually over lays an older submerged crust.

https://community.dur.ac.uk/g.r.foulger/Offprints/OlderCrust.pdf

 

https://community.dur.ac.uk/g.r.foulger/Offprints/crust2003.pdf

 

Some quotes from those documents if you dont feel inclined to delve into them.

 

"An expanse of older crust 210 km wide underlies Iceland, submerged beneath younger lavas

This older crust contributes significantly to crustal thickness beneath Iceland."

 

"In particular, LVZs are expected beneath the major volcano cluster under northwest Vatnajokull (Du & Foulger 2001)"

 

So what exactly does the crust look like under Iceland. Well here is a couple of pictures I have scapped together from various articles.

 

post-2809-0-58759900-1409672902_thumb.jp

post-2809-0-26784400-1409672922_thumb.jp

 

Its not very clear , but here is another one with my interpretation of the boudary between the upper and lower crust parts.

post-2809-0-83630300-1409672988_thumb.jp

Now to me this one suggests that the upper crust might be a little thinner where the volcanoes are and more susceptable to fissures. On the other hand the lower crust might fissure in a different place where it is thinner. There would also be certain frictions between the thick crust below iceland and its possible anchoring towards greenland I would guess. This suggests to me that the lower crust would have a tendency to fissure more to the east of Iceland. The rock dipping down into the mantle would also be more likely to melt and with it being old crust lighter than mantle mangma.

 

post-2809-0-92839100-1409673542_thumb.jp

 

Ok so its just some amateur guess work and may be a complete red herring. The earthquakes below Bárðarbunga also interest me. Some at the moment are quite shallow and I would interpret these as decompression causing the ring faults to adjust. The ring faults in Bárðarbunga seem quite complicated though with inward ring faults to the north and more outward ones to the south. This suggest to me the crater floor has a tendency to tip and wobble under compression and decompression.  The deeper earthquakes are some thing different (down to 11km in some instances) and these may be due to intrusions from beneath, but could also be ring faulting down into a larger magam chamber below (perhaps at the junction of the upper and lower crust).

post-2809-0-74083900-1409673919_thumb.jp

There is off course no evidence to back this model up and there are no gaurantees about whether ring faults down to another magama chamber are inwards or outwards faults, but it does highlight that potentially decompression could in theory lead to more magma flow.

 

Ok so having gone completely off the beaten track into lala land back to the latest statements from the IMO web site.

 

1) A noticeable decrease in seismicity has occurred during the last 24 hours.

2)The eruptive fissure is about 1.5 km in length, positioned about 4.5 km from the ice margin of Dyngjujökull.

 

Ok thats it for this post. Hope it was informative and makes you think a little, but remember I am not a volcanologist and could be completely wrong.

 

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Another great write up Brickfielder, good to have some solid analysis, esp where the IMO won't speculate on how this will play out due to not having a similar historical set of conditions.

 

Just wow at the first vid from the Gases link on Volcano Cafe.... :bomb:  :bomb:  :bomb:

 

 

Epic shot from Time Magazine   http://time.com/3248111/bardarbunga-volcano-photos-close-up-iceland/

 

post-7292-0-82870800-1409676027_thumb.jp

 

Also a new site for all activity, neat layout and format

 

http://avd.is/en/

 

@almannavarnir

Almannavarnadeild ríkislögreglustjóra The National Commissioner Of The Icelandic Police, Department of Civil Protection and Emergency Management

Edited by lorenzo

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whats with these supposed reports of "explosions" heard locally ?

 

or internet gossip ?

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whats with these supposed reports of "explosions" heard locally ?

 

or internet gossip ?

Probably gossip as the seismometer doesn't look very lively.

Karyo

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Probably gossip as the seismometer doesn't look very lively.

Karyo

 

 

the guy that reported it is in touch with the people on the ground so it will probably be real its hard to work out what it was its hard to see on the cams whats going on if the lava is still flowing or has stopped it could be something as simple as the lava stopping and pressure in the fissure changing and causing booming sounds and the smoke was just some ash particles getting ejected we will just need to wait for further news.

 

don't be fooled with the seismometers not showing much it could mean something bigger is building so will still need to keep an eye on things we could end up with the fissure stopping then pressure building in bardarbunga through that.

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Fair enough guys but I generally associate explosions with spikes in earthquake activity.

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Just seen dark puffs on the horizon- another small eruption ! black ash a bit further north of existing #Holuhraun events? #Bardarbunga

 

I would say that a Cambridge prof  that has boots on the ground, could and should be described as an impeccable source.  Would be good if the mila #2 cam did some panning round to see if we can id the source.  Might be nowt more than rockfall kicking up ash but worth keeping an eye on the Cambridge teams tweets to see if they report anything else.

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must be fascinating, amazing, if slightly frightening (although if you know your stuff I'm sure risk can be mitigated to near zero) - to be studying there atm

 

I'm rather jealous

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must be fascinating, amazing, if slightly frightening (although if you know your stuff I'm sure risk can be mitigated to near zero) - to be studying there atm

 

I'm rather jealous

I would love to see this in real life, but am very glad people  like Gisli Dua are there to see this and show us all, outstanding.....post-4726-0-44003100-1409688035_thumb.jp 

 

I hope this fissure keeps up for a while, more on Bada soon I feel, she is not done yet, just awakening from a slumber quite possibly.

 

 

Some sharp spikes at DYN I notice.

post-4726-0-46276000-1409688652_thumb.jp

Edited by Rustynailer

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Amazing photo there Rusty! I love the Aurora  :)

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Amazing photo there Rusty! I love the Aurora  :)

So much more to this eruption I feel, I am sure we are in for more treats too.

 

Note:- When that lava gets to that river it will steam alright...post-4726-0-39305600-1409689985_thumb.jp  post-4726-0-63938400-1409690193_thumb.jp  post-4726-0-79979200-1409690283_thumb.jp

Edited by Rustynailer

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