Posted on by Jón Frímann

Possible harmonic tremor spike in Katla volcano (it might just be the weather)

With all the bad weather in Iceland during the past few days it is hard to be sure on this. But it seems that a harmonic tremor spike is about to start in Katla volcano. So far this spike is rather small from what I can tell at the moment. At the moment it is impossible to know how this develops, if this is a harmonic tremor spike to begin with in Katla volcano.


Current earthquake activity in Katla volcano. Copyright of this picture belongs to Iceland Met Office.


Current tremor levels in Katla volcano. The harmonic tremor spike can be seen at the end of this plot. Copyright of this picture belongs to Iceland Met Office.


The possible harmonic tremor spike in Katla volcano. Copyright of this picture belongs to Iceland Met Office.


The possible harmonic tremor spike in Katla volcano. Copyright of this picture belongs to Iceland Met Office.

This might just be bad weather. It is hard to know at the moment. But currently the weather is decent. But there is a new storm coming over Iceland in the next 12 hours or so, at least that is the weather forecast now from what I can gather.

In September over 480 earthquakes where recorded in Katla volcano caldera. But this is the most earthquake activity since at least the year 1999. The largest earthquake in September in Katla volcano was a ML3.4 with the depth of 5.2 km.

More the earthquake activity in Iceland during the month of September.

Jarðskjálftayfirlit í september 2011 (Vedur.is, Icelandic, Picture)

35 Replies to “Possible harmonic tremor spike in Katla volcano (it might just be the weather)”

  1. Copy & paste from last blog,

    “Que the earthquake swarm at Katla. Though still only poor quality there seems to have been a few deep quakes tonight, one in the centre of the Caldera. Should these be confirmed i reckon a swarm will occur within the next 3-5 days”

    I didn’t think to look for tremors before posting.

  2. is it possible to get a seismogram from those stations, something with decent temporal resolution ? if so , where ?

  3. On the La Gomera frequency display chart for 10/18 there is a flurry of high frequency (14K+) activity prior to and just after the distinct wide spectrum burst and aftershock at 18:04 UT. I had not seen anything like that on any of these displays before. I suppose that was a local activity artifact rather than seismic noise. Anyone with insight as to what this pattern might represent?

    1. I don’t know. None of the other stations have been quiet; I have assumed that they have just been reflecting the activity on El Hierro. There has been some high frequency activity on a few of the station but today’s at La Gomera is particularly strong.

      1. Checked out the waveforms for CHIE and EGOM; they seem to occur at roughly the same time, so I guess they are the same incident.

        http://www.ign.es/ign/head/volcaSenalesDiasAnterioresHora.do?nombreFichero=CHIE_2011-10-19_18-19&estacion=CHIE&Anio=2011&Mes=10&Dia=19&tipo=1&hora=18-19
        http://www.ign.es/ign/head/volcaSenalesDiasAnterioresHora.do?nombreFichero=CHIE_2011-10-19_18-19&estacion=CHIE&Anio=2011&Mes=10&Dia=19&tipo=2&hora=18-19
        http://www.ign.es/ign/head/volcaSenalesDiasAnterioresHora.do?nombreFichero=EGOM_2011-10-19_18-19&estacion=EGOM&Anio=2011&Mes=10&Dia=19&tipo=1&hora=18-19
        http://www.ign.es/ign/head/volcaSenalesDiasAnterioresHora.do?nombreFichero=EGOM_2011-10-19_18-19&estacion=EGOM&Anio=2011&Mes=10&Dia=19&tipo=2&hora=18-19

    1. CA always has a lot of tremors as it is on plate boundary. Do you have the link to USGS showing the specific tremor(s)?

      2. Excitable, not excited. Less than lethargic. Prone to hysteria. Lacking the nuances of a hysteresis curve. Once whose saturable core is fully saturated and goes to full on with the slightest signal. Prone to runaway oscillatory behavior.

        Gawd, I got to stop. I’m starting to confuse myself.

    2. California is both full of earthquakes and volcanic areas. Those things overlap. No reason to worry.

    1. But we know that it is little EldfjallþessierþekktursemBob that has emerged.
      We should probably email them and tell them that the name is EldfjallþessierþekktursemBob.

  7. In regard of the El Hierro artifacts.

    I now have a couple of them.
    They are exactly as I thought, it is bauxite ore.
    Or to be very exact. It is diasporite of the bauxite family with goethite inmixing. They are fragile and of very low mass due to being filled with gas-bubbles. It will take a while though to do isotopy and gas-content tests.
    And no, I haven’t all of a sudden sprouted feathers and become a hot-shot geologist. I just have access to them 😉

      1. Increasing wind here in Reykjavik area, so think its weather related increase around Katla. But there are EQs too. We had a “star” even … off Reykjanes… 🙂

      4. Interesting, it is removed now on the main plot, but not on the Reykjaness Ridge and N-Atlantic plots.
        But, since it does not show on Jóns helicorder I would say it is a ghost. The depth is also generic so…

  9. I have little knowledge of volcanos so be gentle with me.
    My question is, could the shallow small quakes around Katla, be the underneath of the glasier melting from increase in heat from possible magma underneath it trying to push upwards. Just seems to be periods of small shallow quakes and some moderate quakes at depth too. That would make sense to me but i have only ability to guess as i am learning off the more knowlegable on here.

    1. I’m in the same boat as you! I’ve only just recently started to understand some of the pretty-coloured graphs!

    1. O Great Lukring 🙂
      Do you by chance have a plot of this?
      It looks really interesting and I am curious since I have not seen a large volcano re-awake (if this is a reawakening).

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