Question Author
Thanks, Slapshot.
Perhaps I should have been more verbose and said "there's no actual dust cloud yet", which is what I meant.
The earthquake website has been showing a trickle of activity there in recent weeks, likely to be the magma chamber swelling up and or lumps of ice dropping into the caldera and making steam explosions.
What Icelanders are most fearful of is that sometimes there is no airburst but they get massive flash floods coming out of nowhere. It's like liquid concrete and knocks out bridges.