Santorini was the site of one of the largest volcanic eruptions in recorded history: the Minoan eruption (sometimes called the Thera eruption), which occurred about 3,600 years ago at the height of the Minoan civilization. The eruption left a large caldera surrounded by volcanic ash deposits hundreds of meters deep.
All these earthquakes could be due to magma moving its way up. If I had property on that island or close to it, I'd be selling it .