Posted on by Jón Frímann

Special report: The Italy major earthquake swarm

This is a special report on the earthquake swarm in Italy. Due this being a different country I only have limited information about what is going on in Italy and I don’t have complete knowledge of the area in question. News sources with detailed images of the affected earthquake area can be found here (English) and here (Italian). Those news articles also contains images of the affected areas and aftershock areas (I can only use the image from USGS on the English website).

The earthquake swarm in Central Italy

On 26-October-2016 an earthquake swarm started in Italy, it started with a magnitude 5,5 earthquake (EMSC Information). It was followed by a magnitude 6,1 earthquake (EMSC Information). The magnitude 5,5 earthquake is a foreshock (Wikipedia information) to the magnitude 6,1 earthquake and that is the main event in that earthquake swarm. The magnitude 6,5 earthquake (EMSC Information) today (30-October-2016) is a new earthquake swarm in the same area. It has been followed by a heavy aftershock activity, with more than 300 earthquakes/h taking place in the main earthquake area. It is my view, based on the aftershock pattern that one or more magnitude 6,0 or stronger earthquakes are going to happen in this area in the next few days to months (it’s impossible to know when they happen). It does not help that this area of Italy is crossed with fault lines and they are all active (in the sense they can and do make earthquakes every few decades to hundreds of years).

161026-191800-bovz-psn
The magnitude 6,1 earthquake in Central Italy on 26-October-2016. This image is under Creative Commons Licence, please see CC Licence website for details.

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The magnitude 6,5 earthquake in Italy on all axes (Z, N-S, E-W). According to the measurement that I saw on my geophone in Denmark, the movement was N-S rather than E-W. There appears to have been some vertical displacement in this earthquake. This image is under Creative Commons Licence, please see CC Licence website for details.

161030-064000-bovz-psn
High resolution of the vertical component (Z) in my geophone. It clearly shows how the earthquake happened in central Italy. This image is under Creative Commons Licence, please see CC Licence website for details.

It is unclear how this is going to progress over the next few days, weeks and months. I don’t know enough about this area to make any type of guess. The area in question is a subduction zone (just not under a ocean) and that makes predicting this activity even more complicated and difficult.

image-20160824-30259-fv2q41
Basic tectonic layout of Italy with earthquake activity on top. Image is from USGS.

There is also a factor that I don’t know about. How often does this happens over the century in Italy. There is only a small clue (and it’s not even clear) of the earthquake list for Italy on Wikipedia (best that I was able to find). In Iceland (for comparison), the SISZ has an earthquake swarm activity (major) every 13 – 90 years (I wrote a list about known earthquakes here). I don’t know how often this happens in Italy, but I suspect that it is at least every few hundred years. How often this happens is mostly controlled by how fast the faults move each year and I don’t have that information.

If anything more happens in Italy I’m going to update this article.

Update on 01-November-2016 at 23:50 UTC

This morning (1-November-2016) a magnitude 4,9 earthquake (EMSC Information) took place in Central Italy. Aftershock activity continues to be heavy in Central Italy. While this earthquake doesn’t look big, it is enough to create more damage into the effected areas. Aftershock activity continues to be heavy in Central Italy.

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Please remember to support my work with donations. I also want to point out that due to unusual bill situation I’m going to be rather broke in November at best, at worst I’m going to be completely broke (that might mean empty fridge). Thanks for the support. 🙂

Article updated at 23:19 UTC. Word fixes.
Article updated on 1-November-2016 at 23:52 UTC.

34 Replies to “Special report: The Italy major earthquake swarm”

  2. I just wanted to inform you Jón that the conducticity is up to 170 in Múlakvísl and rising. Really a interesting number in this time of year.

    1. Thanks for the information. This is unusually high conductivity number for this time of the year in Múlakvísl, its far from normal. Something might start to happen soon.

    2. I’ve kept an eye on Múlakvísl for a few days, and if my memory serves me right, the conductivity jumped about two days ago and has remained high since. I noticed it because Katla earthquake activity was very low when this started. At the moment conductivity is 188.3 and rising.

      1. Hi Jón,

        Do you know the difference between the high pass and low pass? aside from the visual difference.

      3. Hi Jón,

        Thanks for the explanation, I noticed that yesterday the god high pass seemed to be full of quakes and the low pass didn’t seem to show anything much.

        Did you see the large earthquake on highpass Aus today? it looks pretty huge on the drumplot, how would I see the magnitude of that one?

        Thanks and kind regards,

      5. Thanks for the information ‘Z’, I’m assuming the reason it appears so large on the drumplot then is that it was very shallow and hence close to the detector?

  5. I don’t like the look of that little line of eqs passing by Hekla, that beast doesn’t take much tickling….

  10. Deeper EQ’s than usual at Katla’s caldera. 7km depth the latest one + conductivity in Múlakvísl at 190 now

    1. certainly appears that way, PS I noticed there was a 2.2 mag earthquake listed at around midnight local time which doesn’t seem to appear on the drumplot?

    2. If something is starting in Katla volcano, it’s doing so slowly. Something is making the Goðabunga area of Katla volcano more active then usual.

  12. Regarding the earthquakes in Italy, the Adriatic Sea is on top a micro plate, the Adriatic plate, not the African plate as in this article. I know that a lot of material is showing the Adriatic Sea is on top of the African plate, but…

      1. Yes, entire Italy is bending toward the Adriatic micro plate and is pushing that under Croatia. This is also creating fault lines in SW-NE direction over central Italy and this is where the major earthquakes are happening most frequently.

      1. Yes that was a good description, especially this part:

        “This region is tectonically and geologically complex, involving subduction of the Adria micro-plate beneath Eurasia and the Apennines from east to west, continental collision between the Eurasia and Nubia (Africa) plates building the Alpine mountain belt further to the north, and the opening of the Tyrrhenian basin to the west (the latter of which is in turn related to Adria subduction and eastward trench migration).”

  13. The faults that broke in the Italy earthquake continue to make around 200 – 400 earthquakes over a hours (200 – 400 earthquakes/h). There is a slight fluctuation happening at the moment. I don’t know why that is.

      1. weird it just says connecting then Vefþjónsuppfærsla and then something about redirecting in 10 seconds but its been that way for 3 or 4 hours

  15. “Update in progress

    Our webserver is being updated. Service expected to be available in approx 3-5 minutes.

    English part of our website should be available meanwhile

    You will automatically be redirected to IMO’s home page in about 10 seconds. ”

    but it does not redirect ! I was concerned that something big had happened and there was no Iceland left!

    2. So it’s not my new 4G internet connection, which has gone up from 4Mbs (DSL, currently out of order) to 25(!).

      This post is a test also.

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