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.

Greek officials are warning those on the popular tourist island destination of Santorini to stay alert in the coming days due to increasing seismic activity which could mean a strong earthquake is possible.

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.