They are normal in general. I heard one seismologist after the big one in turkey saying that what is unusual is that lately we dont have bigger ones as we used too, so he said "we know a big one will come (meaning a 6R or bigger) so its better to be prepared."
On the other hand we dont have many swarms here (I can think of the latest around kalamata and the ones around Naupaktos) but I guess the swarm around Santorini is the one caused by magma moving and we didnt have such in the previous years as long as I remember.