iceland Bárðarbunga and Askja - Volcanic Activity

[Allseasons-Si]

its certainly lively

 

hi allseasons

 

annoying no cams tonight

 

Am just hoping for a break in the weather come the next 3-4 days john,it won't be all doom and gloom.

Edited October 5, 2014 by Allseasons-si

[john pike]

looks like late tuesday-early wed morning going by the weather maps

 

getting withdrawals already

 

these look to be running behind at present

 

[Allseasons-Si]

looks like late tuesday-early wed morning going by the weather maps

 

getting withdrawals already

 

these look to be running behind at present

 

LOL

 

i have smoked more cos i am not viewing owt,if barda smoked i will not be smoking then lol

 

i was going to ask you earlier john about drum plots,are they utc time which they are behind 30 mins or more or are they bst which they are 1:30 mins or more behind,i should imagine they are utc.

 

incomming!

 

a 3+ EQ maybe a 4,poss@1-2km

Edited October 5, 2014 by Allseasons-si

[john pike]

hi mate

 

good point i reckon utc as well

 

told you i was getting withdrawals already

 

also if you get a chance look at volcano thread (the other one)

 

check the one but last post

[john pike]

 

up again

[Allseasons-Si]

hi mate

 

good point i reckon utc as well

 

told you i was getting withdrawals already

 

also if you get a chance look at volcano thread (the other one)

 

check the one but last post

 

Yeah,utc

 

http://en.wikipedia.org/wiki/Coordinated_Universal_Time

Edited October 5, 2014 by Allseasons-si

[Allseasons-Si]

 

up again

What are we looking for here john,the uptick in blue,green and red,also,do you have a link to these pls,thanks.

 

also whats with the big gaps?

 

soz for the questions,but you won't learn owt without asking,i am still learning.

Edited October 5, 2014 by Allseasons-si

[john pike]

dyn     http://hraun.vedur.is/ja/oroi/dyn.gif

 

 

http://hraun.vedur.is/ja/oroi/allarsort.html

need to scroll down for kre

 

look at the blue line and green line shoot up together

where you see red at the top its a reasonable size

 

if the red is out of the pic or right near the top its normally quite big

Edited October 5, 2014 by john pike

[john pike]

re the gaps   

 

maybe a data loss

 

but not certain on that one

 

no worries re the learning

 

i think even the experts are learning on this one too

Edited October 5, 2014 by john pike

[Allseasons-Si]

dyn     http://hraun.vedur.is/ja/oroi/dyn.gif

 

 

http://hraun.vedur.is/ja/oroi/allarsort.html

need to scroll down for kre

 

look at the blue line and green line shoot up together

where you see red at the top its a reasonable size

 

if the red is out of the pic or right near the top its normally quite big

Thanks john

 

dyn and von are closest to barda am i right?

 

Edit: yes they are,just looked at the gps map.

Edited October 5, 2014 by Allseasons-si

[john pike]

hi mate

 

correct

 

finally

 

Edited October 5, 2014 by john pike

[john pike]

im off now guys

 

same again tomorow

 

goodnight all

[Allseasons-Si]

im off now guys

 

same again tomorow

 

goodnight all

goodnight john,and thanks again for the info

 

Edited October 5, 2014 by Allseasons-si

[NorthNorfolkWeather]

IMO's website seems to have disappeared.  Been saying it's  being updated for the last 20 minutes

[karyo]

IMO's website seems to have disappeared.  Been saying it's  being updated for the last 20 minutes

Yes, very frustrating!

[Gael_Force]

Yes, very frustrating!

 

That is usually just a problem with the English version - the Icelandic one is operating fine.

 

http://www.vedur.is/skjalftar-og-eldgos/jardskjalftar

 

PS The usual mid-day large one just appearing on the plots now.

 

Edited October 6, 2014 by Gael_Force

[swebby]

A 5.1 and the IMO have it as 0.1km depth, 99% confirmation.  I suspect that will have to change in a later review.

[Gael_Force]

A 5.1 and the IMO have it as 0.1km depth, 99% confirmation.  I suspect that will have to change in a later review.

 

Normally these big quakes show up on all the surrounding stations in equal measure - this one was very localised on the overview plots.

[NorthNorfolkWeather]

That is usually just a problem with the English version - the Icelandic one is operating fine.

 

http://www.vedur.is/skjalftar-og-eldgos/jardskjalftar

 

PS The usual mid-day large one just appearing on the plots now.

 

Thanks

[BrickFielder]

I tried to do some analysis on the earthquakes and those that possibly show reverse faulting. I was typically looking for earthquakes within 3km of Bárðarbunga and thought there may be some sort of pattern.

 

   Date and Time        Depth  Magni    Location.
04.10.2014 21:58:01    7.7km    1.3    0.5km    NE of    Bárðarbunga            
05.10.2014 16:24:41    7.7km    1.8    0.7km    SSE of    Bárðarbunga            
04.10.2014 16:53:12    7.9km    1.4    0.9km    NW of    Bárðarbunga            
06.10.2014 03:40:53    0.7km    0.9    1km    ESE of    Bárðarbunga            
04.10.2014 19:58:59    6.8km    2    1km    ESE of    Bárðarbunga            
05.10.2014 16:25:05    10km    2    1.6km    WNW of    Bárðarbunga            
05.10.2014 07:31:25    6.3km    0.7    1.6km    NW of    Bárðarbunga            
05.10.2014 09:58:20    6.9km    1.5    2km    NW of    Bárðarbunga            
04.10.2014 18:07:41    4.2km    2.1    2.1km    SSE of    Bárðarbunga            
05.10.2014 15:55:49    7.8km    1.4    2.2km    N of    Bárðarbunga            
04.10.2014 22:19:26    9km    3.2    2.2km    SE of    Bárðarbunga            
04.10.2014 22:07:38    5.3km    1.7    2.2km    NW of    Bárðarbunga            
05.10.2014 02:19:27    0.8km    3.4    2.4km    S of    Bárðarbunga            
05.10.2014 08:25:57    1.5km    3.8    2.7km    WSW of    Bárðarbunga            
05.10.2014 09:46:41    5.7km    1.7    2.8km    W of    Bárðarbunga            
05.10.2014 03:44:24    5km    3.6    2.9km    SSE of    Bárðarbunga            
 

The problem is that the focal point of  Bárðarbunga is probably not dead center of the caldera and as far as I can tell tends to be more west and north than the actual center of the caldera. Having said that there does seem to be evidence of reverse faulting going on. 7.5 to 8km deep seems to show some evidence of being a favoured depth. The 9km and 10km depth earthquakes most be close to the magma chamber if estimates of the magma chamber depth are correct  or even in the feeds into the chamber.

 

Analysis of earthquakes possibly outside the caldera rim tend to be located to the north east. Looking at the daily GPS  measurements on the IMO site I think there is a slight tendency for uplift towards the north eastern edge of the caldera rim. The Vonaskard GPS seems to move slowly eastwards without interuption.

 

http://en.vedur.is/earthquakes-and-volcanism/gps-measurements/bardarbunga/

 

http://jardvis.hi.is/gps_timaradir_vid_bardarbungu

 

 

So results are pretty inconclusive in my opinion from the earthquake data, but the reason I was interested was due to the following paper.

 

http://www.academia.edu/8344720/Dike_emplacement_at_Bardarbunga_Iceland_induces_unusual_stress_changes_caldera_deformation_and_earthquakes

 

 

The results show that the dike-induced tensile stress is raised the west-northwest boundary of the Bardarbunga magma chamber/ring-fault early in the episode but concentrates primarily at the southeast boundary . Further modelling (not shown here) suggests that as the dike propagated northeast, the points of maximum tensile stress become shifted somewhat counter-clockwise around the chamber/ring-fault boundary. The maximum compressive stress, by contrasts, concentrates at the north-northeastern and south-southeastern part of the chamber/ring-fault , where the largest earthquakes at Bardarbunga have occurred.

 

earthquakes due to reverse faulting occur on north to northeast striking faults while many normal-faulting earthquakes occur on northwest-striking faults.

 

 

I was interested to see whether current earthquakes confirmed the areas of tensile and compresive stress suggested in the paper. Although I think the stresses are different across the caldera area I am not sure I am totally convinced by the arguments in the paper.

 

So what does it matter anyway ? I am thinking that areas of tensile stress would develop gaps for magma to rise into, which might suggest areas away from the north east part of the caldera might be most likely to see an eruption. Areas of compression are likely to see an eruption when stresses are reduced or when the eruption begins to die down due to lack of magma feed. Thats guess work on my part but the later of the two scenarios feels more sensible to me.

 

Then I wondered whether bookshelf faulting has played a part.

 

http://gef.nerc.ac.uk/documents/reports/914.pdf
 

 

We have found evidence (in the earthquake distribution and fault-plane solutions) for spreading being accommodated by bookshelf faulting in the transfer zone between the Askja and Kverkfjöll rift segments

 

 

I initially thought the odd angle of the fissure may be due to this, but I think it is at the wrong angle. The second thought was does this just apply to areas between the fissure zones or would it apply to the caldera floor as well. So you dont think so, to be honest neither do I, but it might interfere with stress zones, limiting their effect as the book like blocks bend. Incidentally there are some good diagrams it that particular paper which are well worth a look at even if you dont want to read the full paper.

 

So is there anything more we can learn from the krafla fires eruption episode and deformation and stresses induced.

 

http://web.gps.caltech.edu/~avouac/publications/Hollingsworth_JGR2012.pdf

 

Not much except that the caldera moved eastwards as it subsided and there is a risk of dikes freezing if not feed from a deep source.

 

So enough about Bárðarbunga and its caldera, although I would just say that there have been a few earthquakes outside the caldera rim to the NE today, what about the lava reaching the river. Unfortunately weather conditions in Iceland mean we cannot really tell. It is suspected that the river is now being pinched in a few places with the possible prospect of a lake developing at some point in the furture.

 

Enough rambling for today and make sure you take my views as the light heighted bumblings of the village idiot. In other words I am not an expert.

 

 

[john pike]

Monday
06.10.2014 15:15:57 64.644 -17.594 11.7 km 3.2 99.0 3.2 km W of Bárðarbunga Monday
06.10.2014 15:07:30 64.672 -17.492 8.6 km 4.4 99.0 3.9 km NNE of Bárðarbunga

 

deep

 

so the feed looks strong still

 

 

http://en.vedur.is/earthquakes-and-volcanism/earthquakes/#view=table

 

Edited October 6, 2014 by john pike

[john pike]

at present

 

dropping again

 

 

pressure looks to be rising again

Edited October 6, 2014 by john pike

[john pike]

Monday

06.10.2014 16:06:11 64.683 -17.477 6.1 km 4.0 99.0 5.4 km NNE of Bárðarbunga

http://en.vedur.is/earthquakes-and-volcanism/earthquakes/vatnajokull/#view=table

[Midlands Ice Age]

Cuys,

Cams back at Barda though not brilliant.

The eruption as still very trong though.

MIA

[john pike]

Glacial River Retreats as Lava Flow Grows By Eygló Svala Arnarsdóttir October 06, 2014 18:41 Updated: October 06, 2014 18:45

The lava from Holuhraun flows into glacial river Jökulsá á Fjöllum. Photo: Páll Stefánsson.

A new branch of the lava flowing from the Holuhraun eruption is constricting glacial river Jökulsá á Fjöllum, which keeps retreating, as volcanologist Ãrmann Höskuldsson described from the scene, north of Vatnajökull glacier in the northeastern highlands, yesterday.

Five scientists arrived at the eruption site on Thursday after having abandoned it for several days. The new lava now covers an area measuring 50 square km (19 square miles) and it continues expanding, albeit at a slower rate, ruv.is reports.

“[The eruption] is relatively stable. There are pools of lava in the central crater Baugur which bubble. Lava constantly flows out of them and spreads on the sands,†Ãrmann said in description of the volcanic activity at Holuhraun.

The fissure eruption in Holuhraun began five weeks ago, first for a fRichard Linklaterew hours on August 29 and then again on August 31 and has carried on since. While the eruption’s force has declined steadily, there are no indications that it’s about to stop.

Scientists first predicted an upcoming eruption after noticing increased seismic activity in and around volcano Bárðarbunga, which lies underneath the northwestern Vatnajökull icecap, on August 16.

An intrusive dike channels magma from the Bárðarbunga caldera to Holuhraun, an old lava field located north of the glacier. Earthquake activity continues in the area.

 

http://icelandreview.com/news/2014/10/06/glacial-river-retreats-lava-flow-grows