Some other and unknown volcano dedicated to join the spotlight in Iceland by starting making it’s own harmonic tremor. I do not yet know what volcano this is. But most likely it is the Hamarinn volcano. But that is part of Bárðarbunga volcano.
I do not know what volcano is making this noise since there are no earthquakes. But I now find this most likely to be an dike intrusion somewhere close to Skrokkalda SIL stations. Other volcanoes that might be creating this harmonic tremor is the volcano Tungnafellsjökull volcano or the volcano that Skrokkalda SIL station actually is on top of.
But both of those volcanoes have been dormant for an long time now. So I find that to be unlikely, but not impossible. Until a earthquakes happens or something else that actually shows the area of activity in question. This is all just a guess work out in the blue.
Update 1: There is more going on there now then when this first did start. I did record an earthquake from this harmonic tremor around 00:30 UTC. This earthquake was extremely low period as can be seen on this picture.
This earthquake took place around 00:30 UTC on 13. July 2011. It is filtered at 1Hz and is extremely long period earthquake. This suggests that magma did create this earthquake. This picture is released under Creative Commons Attribution-ShareAlike 3.0 Unported License. See the Creative Commons Licence web page for more information.
Blog post updated at 01:02 UTC on 13. July 2011.