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Thread: Let's Talk Iceland

  1. #31
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    Was watching the web cam this morning when I caught an eruption on cam, snap shot (Courtesy of Mila Communications) attached. It's still going strong, and looks like the fissure is near 1km long now total.
    Attached Images Attached Images

  2. #32
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    the flow of lava is close to 1,000 cubic meters per second, which is three to four times the flow during the 2010 Eyjafjallajökull eruption
    That's about 7.5 cubic miles (31.5 cubic km) per year.

  3. #33
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    Still not a lot of ash fall, but the fissure eruption continues at around 100 m3/sec. 2 more > 5 mag quakes in Bįršarbunga Caldera, Iceland Met office has indicated today that an eruption in the Caldera also is possible.

  4. #34
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    Live webcam of the beginning eruption at: https://www.youtube.com/watch?v=zKtGqoxV_qo#t=7855

    Click on the 'Live' dot, bottom line, to make it red and live.
    Just smoke now, it was dramatic last night!
    JOhn

  5. #35
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    Quote Originally Posted by JohnD View Post
    Just to point out.

    The fourth letter of the word for this volcano is not a 'd' but an 'eth', a letter in the Nordic alphabet that looks like a 'd' with crossed upright and pronounced as an unvoiced 'th'.
    Here's help from a friendly Icelander! https://www.youtube.com/watch?v=o5t96V-8_TM

    John
    Languages sometimes really just throw me.... if it's an "unvoiced" sound, doesn't that mean silent? How can it sound like a "th" if it's unvoiced??

    Anyway, thanks everyone for keeping up on this - the web cam views have been awesome and it's good we have people with relevant expertise (or at least a lot of interest) on the forum.

    CJSF
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    I'll be haunting you."

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  6. #36
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    Quote Originally Posted by CJSF View Post
    Languages sometimes really just throw me.... if it's an "unvoiced" sound, doesn't that mean silent? How can it sound like a "th" if it's unvoiced??
    It means your vocal cords don't vibrate.

    Thin is unvoiced.
    This is voiced.

    S is unvoiced (actually it depends, it is unvoiced and then voiced in horses, for example).
    Z is voiced.

    F is unvoiced.
    V is voiced.

  7. #37
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    Hmm... ok.. I get it... I think. Thanks.

    CJSF
    "Flipping this one final switch I'm effectively ensuring that I will be
    Overcoming all resistance long after my remains have been
    Vaporized with extreme prejudice and shot into outer space.

    I'll be haunting you."

    -They Might Be Giants, "I'll Be Haunting You"


    lonelybirder.org

  8. #38
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    Steady State:

    The rate of deformation at GPS sites closest to the dike intrusion has decreased. Together with an overnight decrease in seismicity, this implies that magma inflow appears to match magma outflow at the eruption site.
    Number of tremors over the past day is roughly half that of previous days.

  9. #39
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    Strongest quake in the Caldera, at 5.5 mag this morning. So far all these large quakes in the caldera have been along the caldera's rim. This is expected of both just subsidence, or as precursor to a caldera collapse. Also it appears that recent measurements indicate that the magma inflow into the dyke from the Caldera, is still larger then what is erupting at the fissure.

  10. #40
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    Iceland Met reporting that the tremors at fissure site have stopped today, though lava is still extruding. Quakes at the Caldera still continuing.

  11. #41
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    I've gotten the impression that a fissure eruption is less dangerous than a caldera eruption. Less ash, or something. Is that correct?
    Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.

  12. #42
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    http://www.livefromiceland.is/webcams/bardarbunga-2/

    Extreme telphoto lens, so a little shaky. Not as dramatic as before but still erupting, and in the night dramatic enough. Is that a lava flow from bottom middle towards the left?
    JOhn

  13. #43
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    I have to admit when I look at the URL for that link my brain wants to interpret it as Live Fro Mice Land
    At night the stars put on a show for free (Carole King)

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  14. #44
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    Trebuchet, Yes Fissure eruptions tend to be safer, unless you get to one that is size of the Siberian or Decan Traps, or the Columbia River Breakout. Then ash isn't the problem, but the sheer amount of C02 and SO2 pumped into the atmosphere.

    JohnD, Yes that is the Southern area of the flow. Most of the Lava is heading away from the Cam's to theright and beyond into the flats.


    Two new lava vents have opened up in that Southerner flow area but with minimal fountaining. Tremor activity has been off an on. The Caldera itself is still experiencing quakes, in a pattern around the rim. Another 5.3 magnitude today. That does not seem to be slowing down, so if this level of quake activity continues over then next month in the caldera, I'd place a guess at a 15% probability of a caldera collapse.


    It's low, because, this is likely just what is known as a lateral eruption, where the magma breaks out of the side instead of the top of the volcano. Just this is a very odd one in that the magma traveled some killometers before breaking out. As to how that happened, I'd also guess there was a lava tube down there in place, and there was a EQ that opened up a way between the tube, and the Caldera's magma chamber. There is a Lava tube (TomSawyer Caverns) in Oregon, that's been explored in to 2 miles, and it's assumed from measurements that it goes some 28 miles all the way back to Mt. Jefferson. So a pre-built tube already there is a distinct possibility.
    Last edited by dgavin; 2014-Sep-05 at 02:12 PM.

  15. #45
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    Short Subglacial Eruptions have occurred
    In the surveillance flight yesterday the ice-surface at Bįršarbunga was measured with the radar system of Isavia's aircraft. The measurements show large changes on the ice-surface. Up to 15 m subsidence has occurred in the centre of the caldera, which corresponds to a volume change of 0.25 km3. The shape of the subsidence area is in accordance with the elevation of the caldera floor having lowered by that amount.

    Subsidence of this order has not been observed in Iceland since measurements of crustal movements started around the middle of last century.
    Story includes a nice map.

  16. #46
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    Wow, chances of a caldera collapse....now my guess is about 25% with that information. Hadn't realized the subsidence was that significant.

  17. #47
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    From Ice Met Office today,
    The lava tongue now extends 11 km to the north and has reached the western main branch of Jökulsį į Fjöllum river.
    Also there was a mag 5.4 at the caldera rim.

  18. #48
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    More big quakes around the caldera today. I figure it's gotta fall in at some point.

  19. #49
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    Iceland met staff that were field camping at the oasis at Mt. Heršubreiš, had to evacuate that area today after swarm of quakes occurred there, followed by a significant increase in CO2 emissions. Heršubreiš is about the same distance from the lava flows, as the flows are from the caldera, sort of making the flows the central point of activity in that area.

  20. #50
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    Quote Originally Posted by CaptainToonces View Post
    More big quakes around the caldera today.
    5.2 yesterday and 5.5 today. Caldera continues to sink.
    Last edited by Squink; 2014-Sep-10 at 03:46 PM. Reason: 6 is not 5

  21. #51
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    Another 5.2 Today. Additionally Iceland Met office is now indicating that either a Large Scale Caldera subsidence might occur, causing the fissure to expand and erupt much stronger. Or, also considered as likely, a Caldera Collapse. Bumping my guess for Caldera collapse up to 33% probability.

  22. #52
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    33% seems low to me. I am a layman, but we've been seeing magnitude 5 quakes on a daily basis underneath the caldera for weeks now.

    The magma, it seems, has tried to escape from lower altitude points nearby, but it's still exerting tons of pressure on the glacier and earth holding it down over Bardarbunga caldera.

    How many mag 5 earthquakes does it take for the ice to fall into the molten rock?

  23. #53
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    Well, to be honest, how many does it take? It's completely unknown. The last Caldera collapse that was documented was Krakatoa, and there was no monitoring of that one. They don't happen often enough for a good baseline on them. Like St. Helens which was the first well monitored strata volcano eruption, Bardarbunga if it collapses, will be new science!

  24. #54
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    On that note, the number of larger earthquakes at the caldera have been increasing very slightly in frequency and in strength. If what was learned from strata volcanoes that blow out, applies with a caldera, a large scale subsidence or collapse may involve a magnitude 6 to 8 quake event. So far the strongest event's have been a few 5.4mag.

  25. #55
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    Quote Originally Posted by dgavin View Post
    Well, to be honest, how many does it take? It's completely unknown. The last Caldera collapse that was documented was Krakatoa, and there was no monitoring of that one.
    Also not a lot of ice.
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  26. #56
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    From Iceland Met office:
    The GPS station on top of Bįršarbunga shows a subsidence of the caldera around half a meter over the last 24 hours.
    Unknown if this is a trend increase, or a one time increase. A half meter of a caldera that size, is a fairly significant shifting of mass.

  27. #57
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    The closest web cam is transmitting nothing but white today. I would guess that it finally broke down due to all the shaking from tremors.

  28. #58
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    "Half a meter", dgavin?

    The caldera has subsided by FIFTEEN meters, equivalent to 250 million cubic meters of magma.

    See: http://www.ruv.is/frett/15-meter-sub...rbunga-caldera

    "This much subsidence has never before been measured in Iceland," says geophysicist Magnus Tumi Gudmundsson, a professor at University of Iceland“s Institute of Earth Sciences, "We have not measured an event like this before in Iceland. We probably have to go back to the formation of the Öskjuvatn caldera in Askja, in 1875, when a large explosive eruption occurred there. That event was of course much larger, with subsidence of about 300 meters, but the current one in Bardarbunga is ongoing, and very significant."
    And Askja was an enormous event, that led to thousands of Icelanders emigrating to the USA: http://www.icelandicroots.com/%CF%89...anders-%CF%89/

    JOhn

  29. #59
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    Might want to read what I posted a little better, about the 1/2 meter being in just the last 24 hours......

    Total subsidence is actually over 20m as of today.

  30. #60
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    Oops, sorry, DG!

    Whats the implication of this magma loss? Has it all 'leaked out' into the fault pointing towards Askja, in a sort of safety valve, depressurising a dagerous situation, or is this a precursor of a far more dangerous one? The Icelandic authorities are comparing with the Askja event, which was in a group with Mt.Helen's and second only to Kratatoa and Tambora.
    What's your bet?
    JOhn

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