How was Nisyros volcano island created?

The island of Nisyros is the easternmost part of the active Aegean volcanic arch in Greece and it belongs to an archipelago of several volcanic island such as the peninsula Kefalos on Cos, Yali, Strongyli or Pergousa. Like the other Greek volcanoes of the Aegean arc, Nisyros was created by the displacement of the African plate under the Eurasian plate in front of south Crete-Rhodes. The former sedimentary rocks melt and become lighter than the surrounding mantle and  magma chambers are rising up at a distances of approximately 90-140 km to the north of the sinking plate zones and these magma chambers form the active volcanoes Methana, Milos, Santorini and Nisyros. The youngest magmatic / phreatic eruptions on Nisyros took place 30.000 - 70,000 years ago. The craters in the centre of the caldera are about 2000-5000 years old and belong to hydrothermal explosions. The youngest explosions took place at the Polyvotis craters around 1886 A.D. In November 1995 there was an earthquake crisis starting and  the  awakening of volcanic activity was expected. Since 2000, the island is getting explored in the EU research program Geowarn to get the possibility to predict future eruptions on Nisyros. A relatively dense network of instruments observes the temperatures of the gas outlets, measures the gravity field, examines the rise and fall of the island and of course the earthquake are controlled that happen regularly.