Langjökull quaking and NTV Riddle and the return of Alan’s Evil Riddle

Post by Inge B.

Photo and Copyright IngeB

Photo and Copyright IngeB

Photo from Kalidalur highland road, Langjökull (western side) left, Presthnúkur in the middle, Þórisjökull to the right

There was a unusual swarm of about 20 quakes which took place between Langjökull ice cap and the highland road Kjölur on the western side of the ice cap these last days and it made a new start now.

This is a region which has not been very active lately regarding earthquakes or eruptions.

Source: Icelandic Met Office (IMO), 5 April 2013

There are three main factors influencing Langjökull and its surroundings also regarding the earthquakes occurring there:

  1. glacier mass balance
  2. plate spreading
  3. volcanism

Langjökull is the next biggest Icelandic ice cap (after Vatnajökull), its dimensions being acc. to Wikipedia 925 km² at an volume of 195 km³ and up to 580 m (1,900 ft) thickness. This big glacier though has been receding heavily these last years, probably due to climate change. Scientists even prognosticate this glacier being reduced to next to nothing very soon, if the tend in climate change is continued.

This will of course have an influence on the glacier and its surroundings, eg. due to glacier rebound. This last technical term means that when the enormous weight of the glacier is lifted in a rather short time span, the earth’s crust beneath will move upwards. Near Höfn in the east under Vatnajökull, there has been measured a uplift of over 11 cm in the last years.

Earthquakes may be caused by this kind of “resettling” of earth’s crust.

Wikimedia Commons: Present and former rift zones of Iceland. 1v: Western Rift Zone (WRZ); 1n: Northern Rift Zone (NRZ); 2: former Snæfellsnes-Skagi Rift Zone (SRZ); 3: former Westfjords Rift Zone (WRZ); 4: Eastern Volcanic Zone (EVZ) - most likely a future rift zone.

Wikimedia Commons: Present and former rift zones of Iceland. 1v: Western Rift Zone (WRZ); 1n: Northern Rift Zone (NRZ); 2: former Snæfellsnes-Skagi Rift Zone (SRZ); 3: former Westfjords Rift Zone (WRZ); 4: Eastern Volcanic Zone (EVZ) – most likely a future rift zone.

From commons.wikimedia.org <, 1n=NVZ; 1v=WVZ with Reykjanes; 2 and 3 are former rift zones; 4=EVZ

Then there is the spreading which influences the MAR (Middle Atlantic Ridge) and all parts of Iceland on active spreading ridges. These ridges have been going through several rift jumps in some millions of years. The active rift zone was placed over Snaefellsnes and Vatnsnes, till it shifted over to today’s location which is divided in the south into a Western Volcanic Zone (WVZ) – with Langjökull as its center – and an Eastern Volcanic Zone comprising a.o. the more active volcanoes Hekla, Katla and Grímsvötn. This rift zone has been active now for about 2 million years. Northwards this continues in the NVZ (Northern Volcanic Zone) reaching from the Vatnajökull, over Askja and other volcanic systems out to the sea where it combines with the Kolbeinsey Ridge.

The WVZ has been less active than the Eastern Volcanic Zone during the Holocene, so it is proposed that the spreading zone, the rift is again “jumping” in the south of Iceland. In the whole there were only 17 eruptions representing 64% of its whole production and these took place from around 10.000 BP till about 7000 years ago.

Nevertheless, Langjökull is part of one main zone of the Icelandic rift and MAR, so these quakes could also be part of a rifting episode.

And finally, as with all the big ice caps in the centre of Iceland, also Langjökull is concealing some mysteries. The ice of its cap is not flat. There are mountain tops, nunataks and strange indentations. And after some screening done, scientists discovered not only one, but at least two volcanic systems stretching out under the ice with two calderas under the glacier and two high temperature areas near its edge. There could also be a big table volcano under the ice. And a further high temperature area, the one at Geysir in Haukadalur perhaps connected to one of the systems.

The known volcanic systems under Langjökull are

a) Prestahnúkur, in the southwest, there was sometimes talk about it having some quake swarms in the vicinity and someone – was it Newby – intended to drive up there in a high-wheeler.  The volcano’s tentacles in the form of dikes are reaching at least under Geitlandsjökull, an outlet glacier.

b) Hveravellir in the northeast. This is a famous stop-over for people traversing the country on the Kjölur highland road, with an high temperature area forming sinter terraces.

Image Wikimedia Commons: Hagavatn – View from the southeast on the eastern part of the lake. In the background Hagafell and a glacier tongue of Langjökull, in the foreground the outflow of the lake with the remains of a destroyed bridge.

Image Wikimedia Commons: Hagavatn – View from the southeast on the eastern part of the lake. In the background Hagafell and a glacier tongue of Langjökull, in the foreground the outflow of the lake with the remains of a destroyed bridge.

Lake Hagavatn, not far from the hypocenters.

The hypocenters of the ongoing quake swarm are placed beneath an old lava shield.

Where the deeds are done

Langjökull Glacier

Langjökull Glacier

Source:http://commons.wikimedia.org/wiki/File:Kjolur.jpg

The last eruptions in the Langjökull area took place around the time of settlement in the 10th century when 2 craters on the northwestern side of the glacier shield produced an impressive lava field called Hallmundarhraun (length around 50 km).

Will there soon be another?

Sources:

re. the glacier

re. the volcanism beneath:

http://www.soest.hawaii.edu/GG/FACULTY/SINTON/publications/wvz_g3.pdf

Inge B.

————————————————————————————————

NTV Riddle

*** Beware the red herrings ….
1 point for the volcano 1 point for the red herring

No 1 – Pixar; Sakhalin Oblast; 2001; Citroen; SOLVED Nemo Peak
No 2 – Yellow alert; Dog breed; D.O.C.; Licking County; SOLVED Mt Etna
No 3 – Shield volcano; Scenic railroad; Lahar alert system; Ice caves; SOLVED Mt Rainier
No 4 – Mosquitoes; Inaccessible; Desert; Salt lakes; SOLVED Waw an Namous
No 5 – Spiders; Tiger flowers; Smoke rings; Local Capital; SOLVED Colima

Points …

Diana Barnes 2, Grimmster 3, Inge B 2, El Nathan 2

Kilgharrah

————————————————————————————————

Alan’s Evil Riddle ….

All this stone writing could really give printers the bird!

For a change, 3 alternative answers, so what are they?

Alan C

———————————————————————————————— 

Hekla Eruption Sweepstake …. Who’s gonna wear the ‘bragging rights’ T?

NOT ….
Chryphia March 26th at 19.17
Islander March 26th/27th up to 4pm
Jamie March 26th 23pm to midnight
LAKAT March 27th anytime
Diana Barnes March 27th at 7.30am
Lamiah87 March 27th 12.37
Talla March 28th at 2pm
Georgiade March 29th at 2.30pm
Sam March 29th 4pm onwards
Karenz. March 30th 4pm tp 5pm
Stoneyard April 1st midnight to 4am
Spica April 1st 00am to 06am
Floodwarn April 1st/2nd midday to midday
Inannamoon667 April 1st midday to midnight
CJWINWIN April 2nd anytime
Ursh April 2nd anytime

BUT MAYBE ….
Irpsit April 6th at 8.30am
Newby April 7th 3am to 7am
Cowboy Andre April 9th 1pm to 5pm
El Nathan April 9th late afternoon
Barbara Germany April 12th 6am to 8am
harrie April 12th/13th 8pm to 4am
Bobbi April 14th 2am to 6am
Stephanie Alice Halford April 14th 5.05pm
Denise April 17th midday to midnight
Jim Ludwell April 17th 4am to 11am
Lughduniense April 19th, in the (late) morning
Kilgharrah April 19th midday
Kobba April 20th 9pm and 10pm
Schteve42 April 23rd 6am to 8am
Christian Thordin April 27th 3.30am
Tyler Mannison April 30th midday and 5pm
Bo Minik May 2nd 1pm to 3pm
microcollector May 18th at 8.32am Granyia May18th daylight hours
Grimmster May 21st anytime
Alison May 25th midnight to midday
Summer May 30th anytime
GeoLurking June 25th anytime
Bruce Stout July 1st 1pm
Stefan August 16th 00am to 6am

Kilgharrah

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274 thoughts on “Langjökull quaking and NTV Riddle and the return of Alan’s Evil Riddle

  1. hold on a cotton pickin moment….my ‘not in 2013’ prediction on hekla has been dropped from the ‘but maybe’ list – shocker ! 🙂

    • Ooops sorry a couple were lost during the cut and paste ….. what was it ….. I will re insert!

      • my prediction was that it wouldn’t happen in 2013 (which would be good for the locals) I guess I could have been more specific 🙂

  2. “Palaeozoic, found in shales/slates; apply a little of the old classics”

    Phylum Cnidaria: hydra (second labour of Hercules) or medusa (Jason)

  3. I’ve come down with a head cold so my brain is full of cotton wool. All I can come up with is Sigillaria fossils (common in Cambrian slates) which are possibly the ancestors of the modern quill plants (Tillandsia). Roman sigillaria were impressed words on pottery.

    • I agree, I did notice last night it is within the -XE+03 were x is at -5 now for Hekla and -8 for burfell. If i recall not the biggest slip yet. Wind in the area is not strong, the strain graph has been re-sized 2 times since last night too.

    • Hekla. Only 5,000 to 6,000 units – thats smallish – but it is movement, expect something in region of 300,000 units, but then runup is (probably) already in progress. Re-reading on this, it happens in last 30 min before eruption. Quakes start (used to) 60 to 90 minutes before, and tremour “órói” shortly after. So this be the proper sequence:
      1. Buildup phase (long time), Gas, ground Water changes etc.
      2. Quakes “all sizes, all depths”
      3. tremour “in not to be in doupt version”
      4. Strain fall (or rise), dramatic version

  4. I expect one or more earthquakes in Hekla until the end of the day… after this big change in strain.

  5. Alan’s Evil: Graptolite shales?
    Any of numerous hemichordates of the class Graptolithina. Graptolites form colonies consisting of interlocked cuplike chambers arranged in one or more branches and covered by an exoskeleton. They flourished from the late Cambrian to the early Mississippian Period, and were thought to be extinct until 1992 when scientists discovered what is believed to be a living species. Graptolites are important index fossils used to date the rocks of the Silurian and Ordovician Periods.
    [from Greek graptos: written; from graphein: to write + -lite (from the resemblance of the fossils’ impressions on shale to writings on a slate).]

  6. O/T After the snow, we get fire. Thanks to the strong eastern winds that are blowing for a month, the’re is fire hazard in (North) Belgium and the Netherlands. In some parts it doesn’t rained for a month or only a few inches of snow. The vegetation is still in wintermodus and in combination with the strong dry wind, it’s complete dried out. In the Netherlands there’ve been already a few heathlands/dunes in fire. And the temperature is well below 10°C last month.

    The last time we had fire hazard in belgium was in april 2011 and more than 600ha heathland and +1000ha peat and forest disappeared into the flames. The nature isn’t recovered yet and we don’t have left much of it.

    Here is a video from 2011. At 2.40 you can sea the nuclear plant of Doel (near the port of Antwerp) in the background.

    • What a beautiful landscape! Sad to see it destroyed by fire. Hopefully, it will have the one good, that all plants grow better in coming years.

      • After the fire, Molinia caerulea (purple moor grass), dominated the purple heather. So sheeps were summoned to eat the grasses and restore the heathlands. The sheep are still working on it.

        • Looks like a good area for helicopter and amphibian fire fighting aircraft. in Oregon and California East winds usually late summer and fall-Santa Ana winds are the bane of Calfire But they are hot desert winds….
          I kept hoping that a Eurocopter with a Bambi Bucket or Cl 415 amphib would show up. Not good when the ground crews have little or no air support…
          -Nationally in USA we are near that point right now due to bungling on the part of our national Airtanker program….
          I was mentally drawing entry and departure routes in my head when I looked at the video… Here is a copy of two of my old ships I used and ( soon) will fly again…:
          This is Medford, Oregon 62 and 66 are ex-United DC-7s they are Now owned by
          Erickson Aero..

          • One question comes to mind… how noticeable is the change in lift after the aircraft releases the several thousand pound of load? I would imagine that the aircraft feels a surge in lift as that load is released.

          • It’s Belgium, on average we’ve 200 days of rain. Normally we’ve 50-80mm rain each month. We’re not prepared for big forest fires. With this fire, The Netherlands helped us with a chinook and a bambi bucket. (the fire is near the Dutch border) This video is shot before they were on site. The same month we had also a forest fire at the peat bogs of the Hautes fagnes near the German border in the cross border Eifel National Park. At that time we had assistance of a German Helicopter.

            The last years our springs became much drier, due to changes in the jetstream. Unfortunately, in spring the fire hazard is most likely because there are still a lot of dead/dry plants from the winter and the sun is strong enough to cause trouble.

          • This is an opinion.

            Crown Fires are the worst type, easily sterilizing the grownd in area where they occur. Managed burns that elliminate low and mid sized vegetation lessen the opportunity to fire to get up into the crown. This works great in pine forrests, but I have to idea if it is workable in hardwood forests.

            TGMccoy can probably give a more accurate statement about this. He’s likly dealt with it before (from the air) and it probably has come up in his circle of acquaintances.

          • The high Fens are probably one of the parts of Belgium I love the most. It is Very special on more than one count. The terrain rises dramatically from Stavelot or Eupen (for the tactically inclined, see the battle of the Bulge) and you reach around 700 meters and the top of Belgium (Signal of Botrange) quite fast. The vegetation looks more like the highlands in Scotland than anything else. I remember foundly the Mont Rigi (“mount Rigi”) Inn, lost in the moors and sometimes (often) in the fog. If you get there in the deep of winter, the atmosphere is really unique. As the nice weather will come back I’ll probably get there to do some hiking this summer (and eat some “Soupe Fagnarde” (high Fens’ soup, quite hearty)) with some blueberry pie….

          • Ok with regard to wight changes, the DC7 and P-3’s have what is known as an
            Aero Union tank. Great design.The Tank is mounted with an internal mount in the
            aircraft fuselage. When the retardant is released, you jettison 25,000 lbs. about 11.3metric tons., it depends on the type of drop, slower lighter for grass,heavier,faster for forest/brush..There is not much pitch change, but you can tell that you are now lighter, quickly. In emergency you can salvo the load in about 2 seconds.The DC7 can hold its own with the Turboprops as far as speed and load carrying .
            Forest fuels. We in the US have a forest policy that is at best Bipolar. Europe does a much better job of forest management Crowning fires are a forest killer. heavy ground fuel. no thinning of relplanted, 40-to 100 year stands. Add forest debris/brush you get mega fires. I’m all for controlled burns and it is done some, but, we don’t yet have a
            clue. Now we are down to 8 contracted tankers-from 44 a few years ago. I hope to be working a state of Oregon contract this summer.other states are doing their own
            thing also. Hardwoods are a different animal and I haven’t much experience with them but Fire season is more like spring to early summer in Appalachia because of all the leaf litter. Floodwarn- is that the issue in Wales of just dry conditions.? Ah hates
            arsonists btw.. Spent two weeks chasing one in the Willamette nt’l Forest …
            While on Fire Patrol. caught him , wished I had a pair of Browning .50s in thecowl of the Cessna 182 we were flying…
            sa’ke- sorry about he mistake. My late father-in-law saw Belgium from the driver’s seat of the Sherman tank.ironically his Cousin,(2nd cousin) was on a Flakpanzer crew in the Battle of the Bulge..His Granpa was from Aachen.. After the war , they met up..He liked Belgium ” When no one was actively trying to kill me..”

          • {snicker} You brought up arsonists. Cool story for you.

            Before our county got onto the “paid department” mantra, we had quite a few volunteers. Our station chiefs were usually professionals in other legal and fire service fields.

            One of them had a day job as one of the State Fire investigators, yet another was a Sheriff’s deputy. I don’t know which one this happened to, but in a bar, one of them was in a conversation with another patron. The conversation drifted to that of fire, and the guy bragged about the intensity of a fire that he had set.

            Not really the smartest thing to do. He was arrested on the spot.

          • True, but if the grasses aren’t eaten they push away the heathers and the heathers don’t get the chance to rejuvenate. Purple moor grass was already becoming invasive before the fire.

          • Here in South Wales UK we get wildfires every spring. How bad and how long is very dependant on weather. As some of you know I own the floodwarn website. I am also a watch manager with fire service. These fires are started deliberately by youths and adults. Much wildlife is killed. I have seen dead nesting birds, rabbits and small burroughing animals and even pets that get caught in these fires. It also puts a huge strain on resources. These fires spread towards peoples homes and pidgeon sheds and horse stables. My self I went from the city to 20 miles away. Lots of fire appliances called in to tackle the many fires (150 mountain fires in one day) car accidents and house fires still happen and fighting these deliberate fires could mean it takes longer for us to attend an incident where someone needs our help. Also innocent children or walkers out enjoying the countryside could get trapped by these fires. Its wrong. Its stupid . Its dangerous.

          • In my travels… (yeah, I really had to open it like that eh? I keep an eye out for Dept of Forestry sites. My reason is that it lets me get familiar with where they are at in case I get a service call there. At pretty much every single one, is a large truck with a heavy duty trailer attached. On the trailer, is a dozer.

            Back when I was a volunteer, I saw how these things are used. If the fire is beyond our ability to deal with, and Forestry gets called in, he pulls up in this truck and off loads the dozer. He then cuts a line through the brush with it, establishing a break that the ground fire can’t cross. After that it’s pretty easy (comparatively speaking) to knock it down… at least in this region. On one call we had, we had to scramble to get the truck put back together and race down to the other end of one of these fires to try and get ahead of it when the wind shifted. There were houses exposed on that end. We were almost to the point of trying to go “master stream” until Forestry showed up. “master stream” is where you tag a hydrant and use the monitor to flood what ever it is that you are trying to knock down. Remote monitors can be set up, but there are fed from a larger line and have to be secured to the ground. I’ve only seen them used at one fire. (industrial plant fire where we were trying to keep a stack from collapsing)

          • Its the issue in wales every spring. It can get quite dry. Its the old vegetation from previous years. Gorse, ferns, grass and forestry. Its atleast 99% arson. I have even been o a fire and seen cars stop on the mountain road opposite. Person get out start a fire and get back I car and drive off. Its very rarely glass acting like magnifying glass. Rarely lightning strikes like other countries. This is children youths and even adults that get a buzz out of lighting fires. Thats the situation here in uk. I realise it can be different for other countries. To highlight this the max temperature here I wales this week was just 10c yet every day was very busy. Keen cold wind and dry is all it takes. Quote from the band stereophonics. You can make a thousand matches from one tree but. It only takes one match to burn a thousand trees

  7. This is what Islander said yesterday in response to my similar comment re Hekla strain Spica!

    Hekla. Only 5,000 to 6,000 units – thats smallish – but it is movement, expect something in region of 300,000 units, but then runup is (probably) already in progress. Re-reading on this, it happens in last 30 min before eruption. Quakes start (used to) 60 to 90 minutes before, and tremour “órói” shortly after. So this be the proper sequence:
    1. Buildup phase (long time), Gas, ground Water changes etc.
    2. Quakes “all sizes, all depths”
    3. tremour “in not to be in doupt version”
    4. Strain fall (or rise), dramatic version

    Irpsit also commented that following this drop in strain he expected to see some local EQs in the near future …..

  8. Something went ‘strange’ with a lot of the old posts/comments just a bit ago and wordpress is having some issues today as well, but I believe all is fixed and back to normal again.

    If anyone finds a post which has the wrong author on it, or comments of old posts acting up please drop a mail to the volcanocafe emailadress so someone can take a look at it.

      • I assume that I mistyped the email address but not so sure, having seen Inge B’s comments above. 🙂

    • Indeed, so on the seismographs they hardly show. Maybe a new magma blob coming…
      Btw, lets see what the avatar will do…

  9. Here in South Wales UK we get wildfires every spring. How bad and how long is very dependant on weather. As some of you know I own the floodwarn website. I am also a watch manager with fire service. These fires are started deliberately by youths and adults. Much wildlife is killed. I have seen dead nesting birds, rabbits and small burroughing animals and even pets that get caught in these fires. It also puts a huge strain on resources. These fires spread towards peoples homes and pidgeon sheds and horse stables. My self I went from the city to 20 miles away. Lots of fire appliances called in to tackle the many fires (150 mountain fires in one day) car accidents and house fires still happen and fighting these deliberate fires could mean it takes longer for us to attend an incident where someone needs our help. Also innocent children or walkers out enjoying the countryside could get trapped by these fires. Its wrong. Its stupid . Its dangerous.

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