According to officials, more than 11,000 people have left Santorini, with around 7,000 departing by ferry and 4,000 people leaving by air. Hundreds of earthquakes have rocked the island, the strongest of which was a magnitude five tremor on Tuesday. Major damage has not been reported on the island so far, however officials are taking some precautionary measures. While authorities have closed schools and warned against large indoor gatherings, Prime Minister Kyriakos Mitsotakis has urged calm. The head of the Earthquake Planning and Protection Organisation, Efthymis Lekkas, told ERT - Greece's national broadcaster - that a magnitude six or greater quake couldn't be ruled out.
An additional 51 firefighters and nine vehicles, as well as a fire department helicopter and aerial rescuers have been brought to the island as a precaution. Personnel have also been sent to Amorgos, Ios, Astypalaia and Anafi due to seismic activity in the Cyclades.
"In our country, we have not seen anything similar with so many earthquakes of this magnitude. On the contrary, we see an increase in frequency and magnitude," said the Director of the Geodynamic Institute of Athens, Vasilis Karastathis.
"Things are developing in a way that concerns us... we cannot reassure people," added Mr Karastathis, speaking on ERT radio on Wednesday morning.
Schools in Santorini will remain closed until Friday, while access to Ammoudi, Armeni, Korfos Thirassias and the Old Port of Fira has been suspended. Authorities on the neighbouring islands of Mykonos, Leros, Syros, and Patmos have also closed schools until at least Friday.
Aegean Airlines said it had added nine emergency flights to its schedule following a request from the government. People have been asked to avoid approaching abandoned buildings, choose safe routes in landslip prone areas and empty swimming pools. Santorini welcomes millions of tourists annually, but it's currently low season meaning local residents and workers make up the majority of evacuees.
Kostas Sakavaras, a tour guide who has lived on Santorini for 18 years, left the island with his wife and children on Monday.
"We considered it's a better choice to come to the mainland as a precaution," he told BBC News. "Nothing has been falling, or anything like that," he said, adding that the worst part had been the sound. "That's the most scary part of it," said Mr Sakavaras, who plans to return home once schools reopen.
On Tuesday morning, representatives from the government, armed forces and emergency services met to discuss the situation. The prime minister will chair a similar meeting on Wednesday.