Wild Card's description 
According to Nature (2012), "the largest submerged caldera in the world, Santorini last erupted in 1950 and had been relatively quiet until early 2011, when small earthquakes started to rattle the islands. The region remained fitful throughout 2011, and measurements using the Global Positioning System (GPS) revealed that the eastern and western edges of the caldera had spread apart by 14 centimetres between January 2011 and January this year. Although the earthquake activity died down early in 2012, the sudden changes have left researchers unsure whether the volcano is resuming its slumber or preparing for a future blast."