On 20-May-2014 an earthquake swarm started in Bárðarbunga volcano or a continuum of an earthquake swarm that started on 16-May-2014 as I wrote about here. This earthquake swarm was rather small, with the largest earthquake only having the magnitude of 2,8 according to reviewed results from Icelandic Meteorological Office.
The earthquake swarm in Bárðarbunga volcano. Copyright of this image belongs to Icelandic Meteorological Office.
This earthquake swarm activity seems to be due to minor dike intrusion into Bárðarbunga volcano at this location. It does not mean an eruption is about to take place. More earthquake activity might take place this location in next days to weeks.
Is that a harmonic tremor I see at Grimsfall SIL station Jon?
No. It is just noise from the looks of it. Along with nearby earthquakes and such. Harmonic tremor looks like this when a large eruptions take place. Smaller one do look the same, they are just smaller in magnitude.
http://icelandgeology.net/?p=960
Comment updated at 11:26 UTC.
I’m still watching those SIL traces for Grimsfjall and Skrokkalda, and the pattern of nEQ activity and I have the
feeling the pressure is building under either Bardabunga or Grimsfjall. I know it quitened down after the last
round of EQ’s but it is gradually popping away in two main areas and increasing. When taken with these two SIL
traces it looks suspicious.