Series of substantial earthquakes in the Katla caldera,
could be nothing could be sign of an impending eruption
there are multiple, relatively shallow earthquakes taking place now,
several with magnitude of 3+
earthquake map at 4:10 am (from vedur.is)
it is dark, no other evidence yet, eg no spike in water flow or conductivity in the glacial rivers
webcam at http://ruv.is/katla is down overnight
if the earthquakes continue and get larger, it is a robust sign of impending onset of eruption
PS: still going strong, though the rate of earthquakes has tapered off
GeoLurking has put up a 3D view of the earthquakes in the Katla caldera and Goðabunga in 2011, colour coded by time
you can see the yellow push up and form an incipient fissure on the east side...
to the untutored eye it looks like two magma channels into old craters, a fissure to the east and ongoing growth o the as yet unformed outlet in Goðabunga
will be interesting to see if this tapers off or accelerates