BBC: What is happening in Santorini?
""It is really unprecedented, we have never seen something like this before in [modern times] in Greece," says Dr Athanassios Ganas, research director of the National Observatory of Athens.
....Experts say they're seeing many earthquakes within a relatively small area, which don't fit the pattern of a mainshock-aftershock sequence, says Dr Ganas....
But what is happening now are not volcanic earthquakes, say Dr Ganas. Volcanic earthquakes have a characteristic signature of low frequency wave forms and these have not been exhibited here."