At 19:22 UTC a small earthquake swarm started 14 km east of Akureyri town. The earthquake swarm started with a earthquake with the size of ML3.11 at the depth of 9 km. The area of activity is unusual, but there are none known fault lines in this area that I am aware of. This area is also a bit off TFZ fault zone. This area normally does not have any earthquakes. I am not sure yet if this are intra-plate earthquakes or not, as this area is close to the NVZ (North Volcanic Zone).
This earthquake was felt in Akureyri town by the local people. How well I do not know.
The area where the earthquake swarm is taking place. Copyright of this picture belongs to Iceland Met Office.
I did record the strongest earthquake on enough geophone to be able to make a plot map
from my own software from software called WinQuake that I use to plot earthquakes time, location and depth information with data from Iceland Meteorological Office.
Here is the earthquake location according to my geophones with location data from IMO. This picture is released under Creative Commons licence. See top bar for more information.
Here are the wave form data that where recorded on my geophones (they can be viewed online here). The Sauðárkrókur geophone is a testing geophone that I am currently running. But it is going to be turned off now in December.
The earthquake as it was recorded on the Heklubyggð geophone. This picture is released under Creative Commons licence. See top bar for more information.
The earthquake on Hvammstangi geophone. This picture is released under Creative Commons licence. See top bar for more information.
The test geophone at Sauðárkrókur village. This geophone is noisy. This picture is released under Creative Commons licence. See top bar for more information.
The strongest aftershock that I did record on my Hvammstangi geophone. The wave form data on Sauðárkrókur geophone where not good for some reason. So I do not display them here. This picture is released under Creative Commons licence. See top bar for more information.
The wave form outside the earthquake are ocean waves. They are strong now and show clearly on my geophone. So they appear even more clearly on the SIL network as higher tremor levels. But that is nothing that looks like a volcanic harmonic tremor.
As for the earthquake swarm. It is hard to know what it means. But more aftershocks in this area for the next few days are not impossible. As has been seen before in areas that suddenly start to make earthquakes after a long break.
Icelandic News reports of this event. Please use Google Translate with care. It does not yet understand.
Jarðskjálfti við Akureyri (mbl.is)
Jarðskjálftar við Akureyri (Rúv.is)
Þrír jarðskjálftar nærri Akureyri (Vísir.is)
Blog post updated at 06:02 UTC on 3 December, 2011. Fixing errors in the text.