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.

The strongest earthquake recorded was magnitude 4.6 at 3:55 p.m. Sunday, at a depth of 14 kilometers (9 miles), the Athens Geodynamic Institute said.

Santorini is on high alert following over 200 undersea earthquakes, prompting authorities to close schools and deploy emergency crews. Though the quakes are not linked to its volcano, the increasing seismic activity is concerning,

The FCDO has repeated advice from Greek authorities about seismic activity in and around Santorini but ruled out a repeat of 1956 disaster

A 112 emergency alert was sent on Monday afternoon to those in Santorini, following the series of earthquakes that have occurred over the past few days. The alert informs residents and visitors of the risk of landslides due to ongoing seismic activity. As a precaution, authorities have decided to prohibit access to three areas.

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.

More than 200 tremors have been registered since Friday between the volcanic islands of Santorini and Amorgos, the civil protection ministry said in a statement on Sunday, citing experts tasked with assessing earthquake risks and monitoring Greece’s volcanic arc.

Schools have been shut and public gatherings are being discouraged on the Greek island of Santorini as local authorities put the popular tourist spot on high alert for a big earthquake, following scores of small temblors over the last two days.