Hundreds of people packed a port in Santorini in the early morning hours of Tuesday to board a ferry and reach safety in Athens as a series of quakes kept shaking the famous Greek tourist island.

Hundreds of quakes have been registered every few minutes in the sea between the volcanic islands of Santorini and Amorgos in the Aegean Sea since Friday, prompting authorities to shut schools in Santorini and the small nearby islands of Ios, Amorgos and Anafi until Friday.

A tremor with a magnitude of 4.7 was recorded by the European Mediterranean Seismological Center (EMSC) at 0653GMT on the island most of whose popular white and blue villages cling to steep cliffs over the sea.

“Everything is closed. No one works now. The whole island has emptied,” said Dori, a 18-year-old local resident who declined to give his last name, before boarding the ferry to Athens.

“We will go to Athens until we see how things develop here.”

More people were expected to fly out on an additional flight on Tuesday.

With seismologists estimating that the intense seismic activity could take days or weeks to abate, people were advised to stay out of coastal areas due to the risk of landslides and avoid indoor gatherings.

Some hotels started emptying their pools as they were told that the water load made buildings more vulnerable.

Greece is one of the most earthquake-prone countries in Europe as it sits at the boundary of the African and Eurasian tectonic plates whose constant interaction prompts frequent quakes.

Santorini took its current shape following one of the largest volcanic eruptions in history, around 1600 BC. The last eruption in the area occurred in 1950.