Felt as far away as Athens, the undersea quake caused neither damage nor injuries. It was followed by another 5.0-magnitude tremor two hours later.

According to Athens University, nearly 13,000 tremors have been recorded between January 26 and February 8 in the area between Santorini and the neighboring Aegean islands of Amorgos, Ios and Anafi.

Over 11,000 residents and seasonal workers have left Santorini, normally home to 15,500 people, and the island has been placed on a state of emergency by authorities. Schools were shut last week and will remain closed till Friday.

The tremors have baffled scientists, who say that the region has not experienced seismic activity on this scale since records began in 1964.

Santorini lies atop a dormant volcano which last erupted in 1950.

Visiting the island on Friday, Greek Prime Minister Kyriakos Mitsotakis said that volcanic activity in the area was "not unusual" and did not entail any "immediate, particular danger".

One of Greece's top travel destinations, Santorini attracted about 3.4 million visitors in 2023. Upwards of a million of those were cruise ship passengers.