Having gone through my catalogue of screengrabs for Vatnajokull, I've noted a lot of swarm like activity reported in the Bárðarbunga area around the 5-14km depth range on the following dates since April 2010. 28th May 2010, 26th September 2010, 1st January 2011 and 7th February 2011. Screengrabs reposted below.
There have been a number of similar 'deep swarm' type activity events observed in the same time period along the mid Atlantic spreading zone as it passes through Iceland. Approximate locations from North to South;
1) Tjörnes fracture zone 10-13km NE of GrimseyAll are on the mid Atlantic fault and have been displaying similar swarm activity periodically since I started my observations back in April 2010.
2) Loki area, Vatnajokull
3) Krisuvik area, Rekjanes peninsula
As I am fond of saying; the usual caveats about tremors alone apply. Like Dr Einarsson, I wish there was more data available re ground deformation etc which might give better warning of an eruption and so reduce the guesswork, and therefore the possible damage and disruption.
Volcanoes erupt. It is what they do. It would be helpful if we knew more about when and how big.