Bárðarbunga update

Photograph by Eggert Norðdahl. All rights reserved and used under permission.

Photograph by Eggert Norðdahl. All rights reserved and used under permission.

I once again reiterate that it is Icelandic Met Office and Almannavarnadeild ríkislögreglustjóra that has the authority to issue warnings for Iceland in regards of eruptions and jökulhlaups.

For airborne ash advisories it is in the following order London VAAC and IMO that issues advisories. That being said here follows a brief update.

Almannavarnadeild ríkislögreglustjóra

This is the latest advisory issued.

The Police Commissioner in Húsavík and Seyðisfjörður have decided to close and evacuate the area North of Vatnajökull following the seismic activity in Bárðarbunga.

This decision is a safety measure. It cannot be ruled out that the seismic activity in Bárðarbunga could lead to a volcanic eruption. There is no change in the seismic activity at the moment and no sign of an eruption and but experience shows that seismic activity can be on going for a long time with out an eruption going off. This is first and foremost a precautionary action since the evacuation of the area is impossible on a short notice.

In accordance with procedure, the National Commissioner of the Icelandic Police has raised the Civil Protection level to Alert Phase. All roads leading into the area are now closed and the authorities in Húsavík and Seyðisfjörður are evacuating the area North of Vatnajökull.

The Civil Protection Alert Phase is declared; “if threat assessment shows that hazard is increasing, a preventive measure must be taken immediately to secure the safety of those who are in the area. That is done by strengthening response measures in the area, and by taking preventive actions such as evacuation and closing off the area in question. Increased preparedness and warnings are also common in this phase.”

GPS

BardagpsbNow let us play with the GPS values. Sadly I am not good at all with plotting so I do things by drawing arrows on maps. In this case I will draw arrows on an image from Google Earth. The values I am taking are from five stations. The stations used are Fjórdungsalda (FJOC, Red), Hamarinn (HAFS, Yellow), Vónarskard (VONC, Green) Dyngjujals (DYNC, Blue) & Grimsvötn (GFUM, Black). There is a slight uplift at all stations except at Grimsvötn that has had 20mm of uplift during this crisis.

NOTE, HAFS HAS CHANGED TRAJECTORY TWO DAYS AGO SO THE ARROW IS CORRECT.

I think that the lack of marked uplift is due to separation of the MAR occurring and that the magma is entering into the opening rifts. As such there is no net increase of pressure causing uplift except at the Grimsvötn central volcano.

Now, trying to interpret the orbits of the various GPS-stations is a bit of a headache. But in the end it follows the plate tectonics quite well. The side to the west of the MAR is moving northwards and the eastern side is moving southwards. The division seems to be either along the Veidivötn fissure swarm, or in between Veidivötn and Grimsvötn fissure swarms. The orbit of Dyngjuháls is most likely influenced to go strongly to the east by a local intrusion south of Kistufell. There is no evidence of inflation in Bárdarbunga.

Now for the two arrows that seems to be at odds with each other. Well, Vónarskard is south of the rift zone where the Western arm of the MAR meets the triple junction at Bárdarbunga. From the south comes the South Icelandic Volcanic Zone and then the main MAR goes up north. The plate on the map that is in the southwest is called the Hréppar micro-plate and it seems to be moving east while the part north of the Hréppar is moving to the west.

Photograph by Eggert Norðdahl. Used under permission.

Photograph by Eggert Norðdahl. Used under permission.

No wonder we are seeing such a seismic event. Iceland is having a really bad week from a tectonic standpoint.

Well, this is normally where I go and ask my brother at arms GeoLurking for a plot that explains things, but he is sadly not feeling well right now. I hope he feels better soon for many good reasons.

Ash seems to be fun

Image made by Down Under. Showing trajectories from a 10km ash column for today.

Image made by Down Under. Showing trajectories from a 10km ash column for the 21st.

Now, since this is Iceland and a lot of people remember the ash of Eyjafjallajökull halting air travel I am now incorporating a wonderful ash projection by commenter Down Under. Remember that only London VAAC can issue ash advisories. This is the most likely ash trajectory for the 21st from a 10km ash column.

All the wonderful pictures are once again taken by Eggert Norðdahl. I would like to state that Volcanocafé have been granted publishing rights, if any news agency wish to use the images, or wish to come into contact with Eggert Norðdahl for more images of the upcoming eruption, just send an email to us at our Volcanocafé email.

CARL

Advertisements

501 thoughts on “Bárðarbunga update

  1. And another star:

    Miðvikudagur
    20.08.2014 16:14:04 64,669 -17,462 3,1 km 3,2 99,0 4,4 km NA af Bárðarbungu

    • IMO has Dash-8 TF-SIF with “the works” (Infrared Camera, Synthetic SLAR radar), even comes standard with Canon 5D camera and 100-400L zoom lens and made its first flight there today.
      The Navajo-Chieftain belongs private company Atlants flug and uses callsign “Hekla” …

  2. Thank you for that but there is a lot of cloud cover there. I presume Bardarbunga is just beyond that cloud in the lighter area.

    (Bob was quicker to type than Bardarbunga… couldn’t we rename it to Bar? :D)

    • It seems like there is no uplift showing but is it possible that it could be a dike that is moving up but from the top of the uplift the ground is then pushed away and downwards from the dike (like a slow landslide) so that the GPS appears to be moving away but staying at a fairly stable height compared to previous readings?

  3. First of all what a find, been keeping an eye on these updates since yesterday and they have quickly become a regular refresh and source of interesting discussion/speculation to read. Thank you.

    Second, I am not even what you would call an amateur, but someone in the very early stages of developing interest with a view to maybe some middle aged study and I have have a couple questions and you all seem friendly so hopefully you don’t mind and here goes…

    Looking at the pattern of activity and the growing discussion of dyke formation, is it possible that this dyke could become a ring and we be seeing the early stages of caldera formation?

    Is there any information out there on the location and extent of magma chambers beneath this system and estimates of quantity?

    • Hi GY. Sadly I am older than middle-aged and know very little but so far I have never heard of a dyke becoming a ring. Iceland though does do some very unusual things in the volcanic department. 🙂
      I really think you will have to wait for more info from someone better qualified.

    • Bardarbunga itself has had at least 1 large caldera formation in the past. Some believe it occurred within the last 1000 years. As such, it’s unlikely it has rebuilt its primary magma chamber enough to go through another caldera forming period.

      Keep in mind, you generally need more evolved, explosive magma to form a caldera as well as a lot of load-bearing rock above the roof of a magma chamber. The current situation has three things going against it in terms of caldera formation.

      1. Calderas form due to empty space below the roof not being strong enough to support the rock above it. Shallow magma chambers are inherently less stable than deep chambers due to lower overall support. Additionally, magma chambers with large edifices sitting atop the chamber also are more instable since the chamber bubble itself bears more overall load for holding up the rock above it.

      In this instance, the only volcano that could fit this circumstance is Bardarbunga, but it likely went caldera recently, so that’s extremely unlikely. Also, most of the magma is traveling north from the Bardarbunga volcano into lateral dikes, making a dike eruption much more likely. Lateral rifts in this example are inherently stable formations in terms of collapse events, and they don’t have the requisite magma chambers to have a collapse event of any sort.

      2. Fresh iceland basalt isn’t particularly explosive. When you have magma like this, once the pressure reaches an equilibrium in a magma chamber, the eruption will usually come to a stop without emptying out much of the extra magma in the chamber itself.

      Think of it like this: If you were to pump an excess of water into a soda bottle, then pump an equal excess amount of soda into a separate soda bottle. Shake up both bottles, then uncap them. The soda bottle with water in it will empty out the excess water, but once the pressure from the excess water stops, the bottle will stop overflowing. With the soda bottle, you have not only excess soda trying to escape, but the trapped gases also force out an excess amount of liquid even after the excess liquid has been expelled from the bottle. The void left by the expelled liquid is what creates the inherent instability that allows caldera formation to take place.

      Overall, the problem with basalt is that it generally behaves more like the water in this situation, where chambers rarely expel enough basalt to leave a large enough void for an explosive caldera formation event to occur.

      3. There just isn’t enough magma here at this point to provide a caldera forming eruption. We’ll see how much longer this goes on, but right now, the intrusion simply isn’t large enough for anything huge to happen. I imagine we’ll see where things stand in a month from now.

      • Nice one!
        And that is why my favourite magmas are Dacite and Rhyolite. Basalt is only handy when you need to re-cook those two up 😛

      • Thank you very much

        I hadn’t realised that there was a possible recent caldera event and wondered if the kind of half circle shape of the quake pattern was maybe a suggestion that a larger chamber was letting stuff into a “circular” fracture above it.

        Another question though, I have read that there are some significant rhyolite deposits from previous eruptions, if the dyke encounters some of this and “cooks it up” as Down under suggests, could this make a significant difference, what do we know about the chances of this sitting there waiting for a fry up?

        I have sued the soda bottle demo to show students when explaining volcanoes as part of a general introduction to sciences, really captures their imagination.

  4. > Bardarbunga itself has had at least 1 large caldera formation in the past.
    > Some believe it occurred within the last 1000 years.

    Occurred in the last 10,000 years?

    • A bit on Caldera formation. You don’t have to have some ginormous eruption to have a caldera form. All you need is an “empty” chamber for the roof to collapse into. A stuffed magma “chamber” that then drains out a side fissure can do it.

      The crater of Katmai formed in roughly that way when Novarupta went off about 10 km away and drained the chamber.

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s