Greek authorities are on alert, monitoring increased seismic activity on the island of Santorini, Prime Minister Kyriakos Mitsotakis said on Friday, urging the public to remain calm and follow the advice of the civil protection service.

Greece has declared a state of emergency for the popular tourist island of Santorini following a surge in seismic activity. Hundreds of undersea tremors have rattled the island for almost a week, culminating in a magnitude 5.2 earthquake late on Wednesday – the strongest since the tremors began on 31 January.