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.

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.

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.

As a result of the heightened seismic activity, schools were closed on the nearby islands and residents on Santorini were advised to avoid large indoor gatherings.

Santorini, the popular Greek holiday island, is taking emergency measures in response to intense seismic activity.

Schools were closed and emergency crews deployed on the volcanic Greek island of Santorini on Monday after a spike in seismic activity raised

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.

The mayor of Santorini has called for calm after the island was struck by “intense” tremors for a fourth day in a row.

Greek Prime Minister Kyriakos Mitsotakis appealed for calm Monday after a wave of seismic tremors hit the tourist island of Santorini, prompting concern among locals and hundreds of departures.

Schools were closed and emergency crews deployed on the volcanic Greek island of Santorini on Monday after a spike in seismic activity raised concerns about a potentially powerful earthquake.