iceland Bárðarbunga and Askja - Volcanic Activity

[BrickFielder]

Since I am still puzzling over what the earthquakes at Bárðarbunga mean with regards to the different depths I thought I would share a few incites I have trawled up from the Web.

The first is about ring faults above magma chambers and how decompression of a magma chamber can cause faulting in line with the caldera boundaries. If you want to know more about ring faults (Inward and Outward) and Bárðarbunga in particular see the following link

http://www.geo.uu.nl/~seismain/pdf/2010_Bardarbunga_EPSL.pdf

This might explain some of the shallower earthquakes at Bárðarbunga but not the 6km deep ones. Unless there are two magma chambers one above the other.

This thought led me to another thesis which not only suggest krafla had two magma chambers but there might be a semi molten layer at about 10km down which rifting can tap into for rifting.

Here are a couple of quotes

"Dykes injected from the crustal magma chamber were probably confined to the shallow crust, but dykes at greater depths and at large distances from the caldera may have been engineered by material that ascended from a deeper layer of partial melt [bjornsson, 1985] An alternative explanation for the observed compositional variations is that the magma was drawn from different depths within a layered magma chamber [bjbrnsson, 1985]."

"Einarsson [1991] to hypothesise that they were triggered as a result of a hydraulic link between the central volcanoes of north Iceland, that could be the proposed layer of partial melt at the base of the crust."

"interpreted as inflation and deflation of at least two magma chambers beneath Krafla [Tryggvason, 1994]."

http://etheses.dur.ac.uk/5216/1/5216_2669.PDF?UkUDh:CyT

Is that all clear now or are you even more confused like me. There have been a few earthquakes down below 20km so I am not sure about the partial melt. There does seem to be something going on with the magma chambers under Bárðarbunga and if the fissure filled from another source magma could potential flow back into Bárðarbunga or into Askja. Its all too complex for me to get a grip on at the moment.

I am surprised with all the talk about ash that nobody mentions sulphur dioxide or carbon monoxide emissions especially under high pressure conditions to the east of Iceland.

(Even skimming the links included in this post gave a me a headache with all the mathematics)

[Rustynailer]

Picture of a crack on the surface from Iceland University  https://twitter.com/uni_iceland/status/504692401018241024/photo/1

 

I am surprised with all the talk about ash that nobody mentions sulphur dioxide or carbon monoxide emissions especially under high pressure conditions to the east of Iceland. 

I think there is a global updated map of SO2 somewhere on the net, I remember seeing it when a African small ish volcano called Nabru(?) went off in 2010 ish. Had a huge SO2 plume compared to the eruption.

Edited August 27, 2014 by Rustynailer

[tinybill]

when did the melting in the top right appear I haven't been keeping an eye on the cams at all the last few days?

it was  not there  last  night

[tinybill]

Kverkfjöllum.

http://volcams.malinpebbles.com/pubweb/Iceland.htm

 

look  at  the  cam now there def steam coming out  of  it that was  not there last night, possible  5-6  holes  something  for the clever  ones to have a look at!!!

[Crepuscular Ray]

They've been like that on and off all day. Someone mentioned this morning that it's not an unusual phenomenon there. 

[Evening thunder]

Also it probably relates to temperature and humidity to an extent, for example this morning lots of steam was present, later on as relative humidity had dropped due to higher temperatures, any steam was close to the vents, and now in the evening as it cools more steam is coming back.

 

I noticed this morning that the 3D earthquakes page http://baering.github.io/ showed an additional M5.2 occurred at Askja as well as a M4.5 (not shown by default now as more than 16 hours ago, you'll need to change the timeframe), but the IMO page and their updates made no mention of it (just showing the 4.5 event as well as the 5.2 and 5.4 at Bardarbunga), so assume it must be an error. 

[Shell Rawcliffe]

I wonder if the magma intrusion in to the dyke is having problems with forward momentum.

 

There has not been a >M3 since 3.42am today or frequent >M2.0 as there has been in recent days.

 

Maybe it is because the magma is up against denser rocks now as it move towards Asjka.

 

Don't know much, I am just speculating, more thoughts would be great. 

[Crepuscular Ray]

Last thing I heard, the magma was moving towards Asjka at 4 km a day. Anyone got any details about whether this has continued today or has slowed down?

[Shell Rawcliffe]

Last thing I heard, the magma was moving towards Asjka at 4 km a day. Anyone got any details about whether this has continued today or has slowed down?

 

The IMO update earlier today stated that they believed that it had only migrated northwards 1km since yesterday, which is a significant slow down in its migration northwards.

[Buriedundersnow]

Gisli Olafsson â€@gislio 9m

Photo from @uni_iceland showing new cracks in Holuhraun lava field above main activity pic.twitter.com/SydZ5slkVZ #Bardarbunga

 

 

 

[Rustynailer]

The IMO update earlier today stated that they believed that it had only migrated northwards 1km since yesterday, which is a significant slow down in its migration northwards.

It is still moving forwards over 1 km today, but still no drop in the amount of EQ's, just the size of EQ's has dropped as there (I speculate) is less resistance as the fissures where the head of the swarm is are larger/more extensive.

Edited August 27, 2014 by Rustynailer

[Buriedundersnow]

Gisli Olafsson â€@gislio 3m

6km long cracks discovered north of #Bardarbunga and into #Dyngjujokull during areal recon flight tonight #ashtag

[Rustynailer]

Gisli Olafsson â€@gislio 3m

6km long cracks discovered north of #Bardarbunga and into #Dyngjujokull during areal recon flight tonight #ashtag

Is this picture from Iceland Uni from that flight?

[Shell Rawcliffe]

It is still moving forwards over 1 km today, but still no drop in the amount of EQ's, just the size of EQ's has dropped as there (I speculate) is less resistance as the fissures where the head of the swarm is are larger/more extensive.

 

Okay so it could be the lower resistance the lower the magnitude EQ needed to force it through the rock.  

[NorthNorfolkWeather]

So place your Bets. Is the slowdown due to less resistance or less magma?

I favour less magma, as the overall speed has slowed

Total EQ's over the last 48 hours starting to drop a little

[Rustynailer]

So place your Bets. Is the slowdown due to less resistance or less magma?I favour less magma, as the overall speed has slowedTotal EQ's over the last 48 hours starting to drop a little

There is more area to fill with the same flow rate, if it has stopped there would be no quakes, or rather a lot less than this

[Buriedundersnow]

Is this picture from Iceland Uni from that flight?

 

 

no its on my previous post on the last page its the same place but the crack has opened more

 

So place your Bets. Is the slowdown due to less resistance or less magma?I favour less magma, as the overall speed has slowedTotal EQ's over the last 48 hours starting to drop a little

 

 

it might be because the ground has started to crack and open so less stress in the area

[Buriedundersnow]

mbl.is â€@mblfrettir 6m

An eruption either happened or is currently underway - http://www.mbl.is/frettir/innlent/2014/08/27/an_eruption_either_happened_or_is_underway/ â€¦ #Bardarbunga

Gisli Olafsson â€@gislio 9m

Scientists see substantial indentations/melting at #Bardarbunga caldera - sign that massive heat is melting the ice #ashtag

Gisli Olafsson â€@gislio 7m

Eruption under the #Bardarbunga caldera would take a few hours to melt the ice. Hence hard to tell if it is still ongoing #ashtag

[Rustynailer]

no its on my previous post on the last page its the same place but the crack has opened more

 

http:////f1.nwstatic.co.uk/forum/public/style_images/tctc91_simplify/attachicon.gifBwEHEIXIMAA-chH.jpg

Right, that is probably a sign that a rift eruption is starting or has started. They are reviewing the pictures from that flight and coming to a conclusion that something is amiss.....

Rift eruptions do not always behave the same as volcanoes they do not always make much EQ noise they just exude magma, only when this meets water or certain rock types does it become noisy.

This thing is happening slowly underground I think. The rift that is, soon all that ground where the cracks are will start to fall in I would think. Then we might see some hot rock.

[Buriedundersnow]

Gisli Olafsson â€@gislio 6m

Right now only signs of an #eruption in #Bardarbunga is the indentations in the glacier. May only be a small amount of magma causing melt.

[Buriedundersnow]

defo one to watch here with possible eruption at bardurbunga caldera and cracks appearing over the dyke if bardarbunga was to go it could rip open the fissure and even split askja open as well if the fissure makes it that far.

[Rustynailer]

Gisli Olafsson â€@gislio 6m

Right now only signs of an #eruption in #Bardarbunga is the indentations in the glacier. May only be a small amount of magma causing melt.

http://www.mbl.is/frettir/innlent/2014/08/27/an_eruption_either_happened_or_is_underway/ Basically just what you have pointed out.

 

South of Bada? 

Edited August 27, 2014 by Rustynailer

[Crepuscular Ray]

South of the crater? Is that anywhere near any of the magma movements have been detected?

[Buriedundersnow]

seems they aren't picking anything up on sensors just now so they are unsure what is going on it could just be a big injection of magma into the area which is causing the melting its just a watch and see game just now.

[Shell Rawcliffe]

Could that be a result from the apparent melt water at the Kverkfjoll web cam today?