Greek authorities have warned of an increase in seismic activity around the Aegean tourist island of Santorini, advising people to avoid four ports, empty their pools, refrain from gathering in indoor spaces and shut schools on Monday.

More than 200 tremors have been registered since Friday between the Greek volcanic islands of Santorini and Amorgos.

Increased volcanic activity in Greece’s famed tourist hotspot of Santorini has prompted the country’s civil protection minister to call a meeting with local and disaster response officials.

Greek authorities have issued a warning to visitors to one of its most famous islands due to a surge in volcanic activity.