This overlay map of the island of Santorini in 1848 shows the evolution of the volcano during 150 years :
In 1848, 3 islands were in the center of the caldera : Paleo (ancient) Kaimeni, Neo (new) Kaimeni and Mikro (little) Kaimeni.
Now, Paleo Kaimeni is still the same than in 1848 but Neo and Mikro Kaimeni have merged in one and bigger island.
Still an active volcano !