Short analyse of events of Katla volcano 28th and 29th of July-2017

Icelandic Met Office released interesting graphs of the activity in Katla volcano during the 28th and 29th of July-2017. It gives clues to what might happen just before an eruption in Katla volcano.

Harmonic tremor pulses

On the 28th of July small and short harmonic tremor pulses appeared on SIL stations around Katla volcano. When 29th of July did come the harmonic tremor intensified considerably from what it had been the day before. The harmonic tremor pluses on 28th of July is close to impossible to see on the harmonic tremor plot on Icelandic Met Office website.


Harmonic tremor pluses as they appear on Icelandic Met Office tremor software on 28th of July-2017. Each frequency has it’s own line. Time is horizontal and intensity is vertical. Copyright of this image belongs to Icelandic Met Office.


The harmonic tremor as it is by 29th of July-2017. After midnight the activity intensifies considerably from earlier levels. Copyright of this image belongs to Icelandic Met Office.

This data suggests that before an eruption happens some type of boiling or increase in hydrothermal vents takes place in Katla volcano. This is also connected to the glacier flood that followed into Múlakvísl glacier river.

Glacier flood and harmonic tremor


Blue: Water level. Red: Conductivity. Green: Tremor activity. Values are at 10 minute central value. This data is from the SIL station at Lágu Hvolar. Copyright of this image belongs to Icelandic Met Office.

There seems to be some connection between the harmonic tremor change and the changes in the glacier flood. That suggest in my view that a minor eruption took place in Katla volcano during 28th and 29th of July. How long the eruption did last is a good question. Harmonic tremor data suggests it was only for few hours before it ended. New cracks have been seen around Cauldron 10 in Mýrdalsjökull glacier according to reports. Locations of cauldrons in Mýrdalsjökull glacier can be found here on University of Iceland Earth Science map.

That would be the end of the story in most normal years. Minor eruption and then nothing more. That does not seem to be the case this time around. Small pulses of harmonic tremor have been taking place during the week (Week 31) and that seems to be ongoing process. Most of the tremor pulses are hard to see on the SIL stations and most don’t even appear on more then one or two SIL stations. At the moment Katla volcano is quiet and that might go on for a considerable amount of time due to this minor eruption (my view) and connected glacier flood.

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This entry was posted in Analyse, Earthquakes, Katla / Mýrdalsjökull, Magma, Monitoring, Swarm, Volcano. Bookmark the permalink.

141 Responses to Short analyse of events of Katla volcano 28th and 29th of July-2017

  1. No harmonic tremor but there has been a slight increase in earthquake activity today. Nothing major. Overall activity is quiet in Iceland at the moment.

  2. Jan B says:

    And now a 3.0 in Katla…

  3. The Múlakvísl water height measure is showing a strong zig zag pattern although the water height is not as high as it was when the Jökulhlaup occured fairly recently, and the conductivity is high but not mega high. Any thoughts anyone?

    • Thomas Spencer says:

      Looks like the Water height is showing a strong zig zag again with Conductivity levels still increasing

  4. Thomas Spencer says:

    Does anyone know if these strong spikes mean with Múlakvísl as the water height spikes have been quite strong today, water temp and conductivity have also been quite high as well for a time

    • Old material might be responsible for the spike. If it gets into the glacier river. That might not be the case now. Overall the conductivity remains high in Múlakvísl glacier river.

  5. Porsche928 says:

    I’m betting on a period of 8 hours with no earthquakes.

    http://en.vedur.is/photos/jarisls_rit/170812_2035.png

  6. Henk Weijerstrass says:

    A MW 0.8 at a depth of 18,8 km, 99% quality; 7,2 km south of Básar.
    Isn’t that magmatic Jón? It’s between Eyjafjalla and Katla, isn’t it?
    Magnitude, location and depth are checked, because quality is 99%.
    I know I’ve read once (maybe you wrote it during or right after 2010) that there were some thoughts of shared magma tubes/connections between Eyja and Katla.
    Any thoughts about that?
    Kind regards,
    Henk

    • Eyjafjallajökull volcano is cooling down. This is I guess just an earthquake due to that process. Expect to see this type of earthquake activity in Eyjafjallajökull volcano at least until the year 2030 or longer. Since it takes a long time for a volcano to cool down.

  7. Saara R says:

    Some interesting tremor at god lowpass.
    http://hraun.vedur.is/ja/drumplot/drumplot/god_lowpass_0.7.png
    Might not be all that significant though because it doesn’t show in other drumplots.

    In other news, conductivity is rising steadily and it seems that those weird little pulses are once again visible in highpass data.

    No great drama, but something seems to be going on.

    • Thomas Spencer says:

      Looks like a few stations have picked up a tremor again, still looks fairly quiet though. Not sure if the Mýrdalsjökull is worth keeping an eye on

  8. Thomas Spencer says:

    Conductivity now higher than it was yesterday with it currently being 224. Spikes with Water height are not as big as yesterday but still looks a little strong and has been like that for more than 24 hours now. Plus a few bigger spikes with Water temperature from what I can see

    • Thomas Spencer says:

      Another fairly big tremor has showed up on a few stations again like earlier and also Conductivity is increasing quite a bit, thoughts?

      • There is a strong earthquake swarm deep south of Iceland. Largest earthquake so far has the magnitude of Mw5,1 and there are many magnitude 4,5 – 4,9 earthquakes happening at the moment.

        The distance is around ~1800 km south of Reykjavík.

        The Mw5,1 earthquake, https://www.emsc-csem.org/Earthquake/earthquake.php?id=611967

      • Thomas Spencer says:

        Ah right, thanks. Do you think this will do much to Katla at the moment?

      • I think Katla volcano quiet period is going to continue as is. This might even be like 2011 July activity. After the small eruption (larger then 28 – 29 July 2017 event) activity did drop in Katla volcano for many months afterwards. I suspect that might be the case now.

        But we will see what happens next.

      • Z says:

        Jon, isn’t it a bit difficult to compare the 2011 subglacial eruption to the recent one (that perhaps wasn’t even an eruption)?

        The accumulated seismic moment since last summer is almost 4 times greater than the five previous years (2011-2016) combined, which should make the current Katla situation very different.

        It does sound reasonable, however, that the activities of July 28-29th will be followed by a calm period. I just don’t think it will be years this time until activity sparks up again.

      • I don’t think seismic energy is a important factor when it comes to Katla volcano minor eruptions. The build up to a minor eruptions seems to be a short term increase in earthquake activity then a minor eruption happens and then everything goes quiet for a while.

        The only other volcano that I’ve seen behaving in this same way is Hamarinn volcano south-west of Bárðarbunga volcano.

  9. Elmar Þor Benediktsson says:

    Any ideas about Haukadalur and Hekla this last Hours?

    • Haukadalur SIL station appears to be road traffic or something else human made. This is not on other SIL stations that are nearby so it is highly local source.

  10. Thomas Spencer says:

    I assume it’s wind noise being picked up in some of the SIL stations such as Aus and God at the moment?

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