Santorini is on what is known as the Hellenic Volcanic Arc but the last major eruption was in 1950. Greek authorities have said that the recent movements are not related to volcanic activity and have started to subside.

The tremors recorded by geologists are considered minor or light, but authorities have recommended a number of preventative measures in addition to the school closure including to avoiding the ports of Ammoudi and Fira.

Big cruise ships often anchor near the Old Port of Fira, with passengers being brought to shore on smaller boats.

One of the largest volcanic eruptions in history, around 1600BC, formed the island as it stands today.