Ischia is an island consisting of several volcanoes, which rises for about 900m from the sea floor, in the north-western part of the Gulf of Naples. Eruptions have occurred until 1302, the year of the last event: the accumulation of volcanic products has thus built an island about 46km2 wide that reaches a maximum height of 787m above sea level, at Mount Epomeo.
Most of the island is constituted by deposits of both effusive and explosive eruptions, which have built volcanic buildings, some of which are still clearly visible in the south-eastern sector of the island, others completely dismantled or buried. Landslide deposits are also widespread, resulting from the accumulation of pre-existing volcanic material.
Ischia is a volcanic complex that has had different periods of activity and also gave rise to large explosive eruptions.
The event that has marked the geological history of the island is the eruption of the Green Tuff of Epomeo. The eruption, highly explosive, occurred about 55,000 years ago, and is responsible for the formation of a caldera, which occupied the area where the central part of the island is today. The formation of pyroclastic flows has partially filled the caldera depression, which in the meantime had been invaded by the sea, and has partly covered the areas then emerged.
After the Green Tuff eruption, volcanic activity continued with a series of explosive eruptions until about 33,000 years ago. Approximately 10,000 years ago, after a relatively long period of stasis, the activity continued even in historical times with a series of eruptions. The last one, which occurred in 1302 AD, determined the formation of the Arso lava flow.