It comes after amagnitude 5.2 tremor was recorded at 21:09 local time (19:09 GMT) on Wednesday between the Greek islands of Amorgos and Santorini,making it the strongest in recent days. It is estimated to have occurred at a depth of 5km (3.1 miles).

The decree will be in effect until 3 March to “address the emergency needs and manage the consequences”, officials said.

More than 11,000 people have already left Santorini, with around 7,000 departing by ferry and 4,000 by air.

A 4.7 magnitude quake was also recorded south-west of Amorgos at 07:50 local time on Thursday, following 57 tremors between midnight and 06:30.

So far no major damage has been reported on the island, butauthorities are preparing in case a larger quake hits.

Greek Prime Minister Kyriakos Mitsotakis is expected to visit Santorini on Friday.

Vasilis Karastathis, director of the Geodynamic Institute, told Greek state-owned broadcaster ERT News that “seismicity continues at the same pace as in previous days, intense”.

“We have a fairly high number of earthquakes with magnitudes above 4,” he said.

“We are still in the middle of the road. We have not seen any thinning, any sign that it is heading towards retreat.”

Santorini welcomes millions of tourists annually, but it is currently low season, meaning local residents and workers make up the majority of evacuees.

Due to the state of emergency, repairs to things like public roads and ports can skip usual bureaucratic requirements and begin immediately.

“We are in a particularly uncertain stage, where we cannot accurately determine the duration of the seismic swarm nor its exact origin,” Costas Synolakis, a professor of natural disasters, told ERTNews.

He said it is necessary to remain prepared for the possibility of a larger earthquake and a “volcanic crisis” like the one in Santorini.

To cope with this, extra generators have arrived and a backup telecommunications station is being set up at Santorini City Hall.

Islanders also fear of a tsunami, with makeshift defences built from sacks along Monolithos beach in Santorini, where the buildings are very close to the sea.

All hospital employees are on standby to help those who have remained on the island with all leave and days off cancelled.

Additional ambulance crews, police officers, soldiers and military vehicles have also arrived in Santorini, with medical personnel sent from Naxos, another island.

Vassilis Kikilias, the climate and civil protection minister, said units of firefighters trained in natural disasters were being despatched to Santorini.

Teams with special dogs and a mobile operations centre have also been sent to the island, while helicopters are on standby.

Kikilias also said the coast guard and armed forces would be available to assist vulnerable people who wish to evacuate.

Poor weather means the ferry from Santorini to Piraeus port near Athens is not operating. The adverse conditions are expected to continue over the coming days.

Many travellers remain at Santorini’s port to board emergency ferry routes that have been set up.

Schools on Santorini – and other neighbouring islands including Anafi, Paros, Naxos and Mykonos – will remain closed until Friday, when authorities will make a decision about when they can re-open.

Earlier on Wednesday, Greek Prime Minister Kyriakos Mitsotakis had struck an optimistic tone at a meeting of civil protection experts.

“All plans have been implemented. Forces have been moved to Santorini and the other islands, so that we are ready for any eventuality,” he said.

He asked the islanders to “stay calm and cooperate with the authorities”.

The Thira Chamber of Commerce earlier called for business on the island to be suspended and emergency support measures be taken in line with those during Covid-19.

Santorini is on what is known as the Hellenic Volcanic Arc – a chain of islands created by volcanoes – but the last major eruption was in the 1950s.

Greek authorities have said the recent tremors were related to tectonic plate movements, not volcanic activity.

Scientists cannot predict the exact timing, size or location of earthquakes.

But there are areas of the world where they are more likely to occur, which helps governments prepare.

Earthquakes are the result of movement of tectonic plates in the earth’s crust. Sometimes these plates lock together when they meet, which is called a plate boundary or a fault line.

Santorini and the other Greek Islands are near such a line.

The owner of the Isias Grand, Ahmet Bozkurt, and architect Erdem Yilmaz, were each given 18 years and five months, the official Anadolu news agency reported. Bozkurt’s son, Mehmet Fatih, was sentenced to 17 years and four months, it said.

The hotel, in the south-eastern city of Adiyaman, was hosting a school volleyball team from Turkish-controlled northern Cyprus and a group of tourist guides when the quake hit last February.

The three men were convicted of “causing the death or injury of more than one person through conscious negligence”, Anadolou said.

Turkish Cypriot Prime Minister Unal Ustel said the sentences were too lenient and that authorities would appeal, AFP new agency reported.

“Hotel owners did not get the punishment we had expected,” Ustel said. “But despite that, everyone from those responsible in the hotel’s construction to the architect was sentenced. That made us partially happy.”

More than 50,000 people died in Turkey and Syria in the quake on 6 February 2023.

Some 160,000 buildings collapsed or were badly damaged, leaving 1.5 million people homeless.

The Turkish government said a few weeks later that hundreds of people were under investigation and nearly 200 people had been arrested, including construction contractors and property owners.

A group of 39 people, including boys and girls, teachers and parents from Famagusta Turkish Education College, had travelled to Adiyaman for a volleyball tournament when the earthquake struck.

Four parents were the only survivors among them. They managed to dig themselves out of the rubble, while 35 others including all the children were killed.

The volleyball group had picked the seven-storey Isias Grand, along with as many as 40 tourist guides who were there for training.

It was one of Adiyaman’s best-known hotels but it collapsed in moments.

The Isias had been operating since 2001 but, according to scientific analysis, gravel and sand from the local river had been mixed with other construction materials to form the columns supporting the building.

The sheer scale of building collapses in the earthquake prompted widespread criticism of the Turkish government for encouraging a construction boom while failing to enforce building regulations, which had been tightened after earlier disasters.