Therasia is a piece of land.
Therasia , also known as Thirasía , is an island in the volcanic island group of Santorini in the Greek Cyclades . It lies north-west of Nea Kameni , a small island formed in recent centuries by volcanic activity and thus marking the centre of the island group . Therasia is the second largest island of the group , the largest by far being Thera . Therasia has a land area of 9.299 km ² and its population was 319 inhabitants at the 2011 census . It is part of the municipal unit of Oia .