Hekla Ready to Erupt?

Hekla at predawn on April 14th, 2012. (Mila webcam capture)

Hekla at predawn on April 14th, 2012. (Mila webcam capture)

According to an article published today by journalist Kristján Kristjánsson on the Icelandic Internet news outlet Pressan, “Hekla is ready to erupt” and “tension is very high in the mountain”. The article, which is in Icelandic, goes on to quote (Professor) Páll Einarsson, the man who rightly won international acclaim in 2000 when he read the signs correctly and famously said that Hekla would erupt at 18:15 hours, thirty minutes before the event which duly arrived at 18:18 hours. From what the article says, it is obvious that the writer is quoting an old interview made years ago.

However, even if this article gives the impression that an eruption is imminent this is not necessarily so! First of all, neither IMO nor Almannavarnir, the organisation responsible for public safety, make any mention of noteworthy unrest at Hekla. Second, the instrumentation publicly available courtesy of the IMO show little or no signs that an eruption could be imminent even if Hekla is famous for giving little or no advance sign until less than an hour before an eruption begins.

“So what should I look for?”, you ask. Well, let me run through a few useful websites and what to look for! First of all, regularly check the IMO earthquake page for Myrdalsjökull:

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

IMO page for the Myrdalsjökull area June 20th, 2016. Note earthquake at Hekla, a M 1.1 at 9.6 km depth (IMO)

IMO page for the Myrdalsjökull area June 20th, 2016. Note earthquake at Hekla, a M 1.1 at 9.6 km depth (IMO)

If the map shows earthquakes at or very close to Hekla, a look at the special page devoted to Hekla, Heklavöktun, is indicated. On this page, there are links to most instruments monitoring Hekla as well the information available from the year 2000 eruption for comparison. I have placed the relevant comments in the image captions:

http://hraun.vedur.is/ja/hekla/

Borehole strain and seismicity (IMO). Please note the scale on the strain count! This changes and is currently high but can be as low as 1/50th of the one on display. Needless to say, if the scale is set to show minor movement, these appear large without this signifying anything in particular. When it comes to earthquakes, large distant earthquakes will show up as they did during the 2014-5 Bardarbunga eruption. Make certain that an earthquake showing on this graphic is indeed at Hekla and not a distant event! At the bottom of this part of the page is a quicklink to the five strain meters.

Borehole strain and seismicity (IMO). Please note the scale on the strain count! This changes and is currently high but can be as low as 1/50th of the one on display. Needless to say, if the scale is set to show minor movement, these appear large without this signifying anything in particular. When it comes to earthquakes, large distant earthquakes will show up as they did during the 2014-5 Bardarbunga eruption. Make certain that an earthquake showing on this graphic is indeed at Hekla and not a distant event! At the bottom of this part of the page is a quicklink to the five strain meters.

Strain stn Hekla

Borehole strain at station Hekla (IMO). The strain measured varies naturally with the tides. If there is a change due to volcanic unrest, the strain will deviate sharply and unmistakably from this normal, slow undulation. Please note that the instrument is so sensitive that large earthquakes; ~M 4-5 elsewhere in Iceland and M 7 or larger worldwide, tend to show up here.

The page also has links to the three SIL-stations closest to Hekla. The image shows tremor registered at Haukadalur SIL-station during the year 2000 eruption. (IMO) Please note how very unmistakable the immediate, sharp rise is!

The page also has links to the three SIL-stations closest to Hekla. The image shows tremor registered at Haukadalur SIL-station during the year 2000 eruption. (IMO) Please note how very unmistakable the immediate, sharp rise is!

Finally, the page contains links to several additional webcams including the “Burfell Dalek” looking at Hekla from the North. (IMO)

Finally, the page contains links to several additional webcams including the “Burfell Dalek” looking at Hekla from the North. (IMO)

There is an additional instrument monitoring Hekla available online, the Fedgar drum plot which is accessed through the IMO-supplied page “Tromlurit” or directly via the link at the bottom of the page.

Fedgar drum plot (IMO). At present, the weather is rather heavy which is the reason for the thickness of the lines. Please note that most of the earthquakes shown here are actually teleseisms from more distant quakes, something that can be confused with harmonic tremor by the untrained eye as they are very drawn-out and lack the sharp peaks of the P- and S-waves of regular tectonic earthquakes.

Fedgar drum plot (IMO). At present, the weather is rather heavy which is the reason for the thickness of the lines. Please note that most of the earthquakes shown here are actually teleseisms from more distant quakes, something that can be confused with harmonic tremor by the untrained eye as they are very drawn-out and lack the sharp peaks of the P- and S-waves of regular tectonic earthquakes.

So, is Hekla about to erupt? To judge from what the instrumentation shows, no. The article was probably intended to attract traffic to the site rather than factual reporting. BUT! Hekla is so unpredictable and gives such scant warning that by the time I have finished writing this article and published it, Hekla could indeed be in the process of erupting!

Henrik

 

http://www.pressan.is/Frettir/Lesafrett/hekla-er-tilbuin-til-ad-gjosa-mikill-thrystingur-i-fjallinu

http://www.almannavarnir.is/

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

http://hraun.vedur.is/ja/hekla/

http://hraun.vedur.is/ja/drumplot/drumplot/fed.png?0.8531966300332475

http://www.livefromiceland.is/webcams/hekla/

I have added the links to two of Icelands reliable news agencies; RUV and MBL in case there is another unconfirmed story as these two are pretty quick to publish accurate information.

http://www.ruv.is/

http://www.mbl.is/frettir/

 

 

 

225 thoughts on “Hekla Ready to Erupt?

  1. Regarding the steam in Jokulsa webcam today:

    I asked Jon from jonfr.com and he told me it is HOLUHRAUN actually. He thinks water might have seeped into the cooling magma, for some reason and the large steaming occurred. I only remember seeing such large steaming right after the Holuhraun eruption finished but sometimes large-scale steaming can occur when water finds a path to still-hot magma that is cooling down, further deep. I remember seeing Eyjafjallajokull steaming greatly back in mid 2011, one day, then it was gone the day after.

    Still with the increasing restless of Bardarbunga and knowing that magma is moving there (and it could obviously be moving again along the rifting dike), I can´t exclude the hypothesis that this magma might reach the Holuhraun crater and re-start the eruption there. Especially as we see today Holuhraun steaming unusually strong.

    Remember I had the theory, still hold to it, that Holuhraun was in fact a shield volcano type of eruption (Irpsitdyngja!), which is somewhat common north of Bardarbunga. In fact north of Bardarbunga, rifting fissures are somewhat rare, but they do happen (like in 1875 Askja eruption). Contrasting to south of Bardarbunga where long rifting fissures are the only form of eruptive behavior and there are no shield volcanoes (examples of Laki or Veidivotn).

    Shield volcanoes often start and stop and then start again, for many years of eruptive behavior. There have been shield volcanoes in Iceland which have erupted somehow non-stop for decades (probably with minor breaks in between lasting a few months or couple of years) (example Skjaldbreidur). And they do erupt massive amounts of lava, but along those slow-rate long-lasting nearly continuous eruptions.

    Time will show us whether Holuhraun was just a one-time fissure event or it will build up to a shield volcano in such a manner. (Shield volcanoes often start with fissures but then one crater becomes dominant and build the shield volcano). Perhaps time to pay attention to Holuhraun again…

    • I agree that the steaming is probably just water that has seeped into still hot lava. This time of year, water levels change a lot all the time, due to melt water runoff, so it’s very likely that some stream has gone into a hot part of the lava field. In all likelihood the steaming has nothing to do with increased activity at Bárðarbunga.

      As for a new eruption at Holuhraun, I wouldn’t hold my breath. The width of the dyke matches exactly the accumulated plate separation since last eruption. This means that all accumulated strain was released, so there is nothing left for any further rifting to occur. The dyke is now full of solidified magma, so even pressure levels at Bárðarbunga like the ones before the eruption wouldn’t be able to squeeze any magma through. We’ll probably have to wait another hundred years or so before anything happens there again.

      I have my thoughts clear about what’s going on in Bárðarbunga, but I’ll hold on to them for a while. Vacation time is coming up, so maybe I’ll write something in a couple of weeks.

  2. “Still with the increasing restless of Bardarbunga and knowing that magma is moving there (and it could obviously be moving again along the rifting dike), I can´t exclude the hypothesis that this magma might reach the Holuhraun crater and re-start the eruption there. Especially as we see today Holuhraun steaming unusually strong.”

    I’ve thought the same thing when i posted Jokulsa webcam steam, but i wasn’t sure of webcam position. Perhaps an eruption could take place this summer in Irpsitdyngja or in that area, between Holuhraun and the glacier, it’s an option(IMO).

  3. A long swarm of M4.5-5 quakes far south in the Reykjanes ridge. Source IRIS seismic monitor. Moving north and if it continues it will soon be within the IMO north atlantic panel. Will the zipper rift all the way up to Iceland?!

  4. There is a new article about the steam.
    http://en.vedur.is/earthquakes-and-volcanism/articles/nr/3158

    Steam plumes from Holuhraun lava field
    -28.6.2015
    Over the past weeks, steam plumes have been seen rising from the Holuhraun lava field. These plumes are not signs of a new eruption. The steam plumes are the consequence of partly solidified lava interacting with water. Meltwater in the outlet rivers from the Dyngjujökull glacier has been increasing, resulting in water coming into contact with the cooling lava front. It is likely that such steam plumes will continue to be seen in the weeks to come.

    • More or less what I thought…, I just wanted to post this: My uneducated guess is that the steam is the result of: new lava inflow at Barðie that heats up the old lava flows reaching into Hohluhraun, plus the jökulhlaup from the cauldrons on top of Barðie are overflowing an area with warm lava underneath. It would be interesting to see an aerial photo of the jökulhlaup and where the water goes.

      As for the requested image: it’s already there 🙂

    • New? Not from the date, or perhaps I’ve missed something.

      @Lughduniense (nice user name, btw), the cauldron(s) drains SW down the Skafta.

  5. Couple of what I call ‘micro creaks’ in an interesting place; deep under the North flank of Hekla:

    27.06.2016 07:10:47 64.041 -19.630 8.2 km 0.4 99.0 5.8 km NNE of Hekla
    27.06.2016 07:08:49 64.046 -19.622 9.4 km 0.3 99.0 6.4 km NNE of Hekla

    Interesting for such small quakes that they got to 99% – i.e. manually checked – quite quickly.

    • I expect that the ’99’ refers to the reality of the earthquake. The depth would be much harder to get right for a weak quake and may be more uncertain.

  6. These two are also a bit interesting (dead zone). They have still not been manually verified and the quality is poor, but the placement by the automatic system is directly on top of the old Eldgjá fissure:

    26.06.2016 22:19:50 63,890 -18,775 0,5 km 0,5 59,52 17,9 km SA af Landmannalaugum
    26.06.2016 22:14:48 63,767 -18,934 5,1 km 0,6 35,06 17,7 km SA af Álftavatni

    • I am actually a black swan event in the making. Expect me in 2025. Following Katla eruption.

    • “… This process is common in the aftermath of volcanic eruptions….”
      (IMO)
      What about EQ magnitude 3-4? Normal processus?

      • sorry, not familliar with word press. add resp: ” at these depth ” and “for inflow of magma below Bárðarbunga”

        Note: French TV (TF1) changes the name of a street in Nice:
        “Promenade des Anglais” to “Promenade des Islandais”

      • It is probably not unexpected: the eruption removed a lot of weight from Bardarbunga and would have left it underpressured. So if there is some magma around, it can be sucked into the empty reservoir. But how normal it is is hard to tell: no aftermath of such an eruption has been observed this well before. Let’s see how it develops. Will hte earthquakes intensify, stay the same or calm down?

  7. so what they are saying is this is just normal activity after after an rifting event ?.

  8. After the minor earthquake swarms south west of Mauna Loa, today there was a quake on the southeast side. Not clear whether this is inflation from Mauna Loa or pressure from Kilauea.

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