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.

Precautions were also ordered on several nearby Aegean Sea islands – all popular summer vacation destinations – after more than 200 undersea earthquakes were recorded in the area over the past three days.

“We have a very intense geological phenomenon to handle,” Prime Minister Kyriakos Mitsotakis said from Brussels, where he was attending a European meeting.

"I want to ask our islanders first and foremost to remain calm, to listen to the instructions of the Civil Protection (authority)."

Mobile phones on the island blared with alert warnings about the potential for rock slides, while several earthquakes caused loud rumbles. Authorities banned access to some seaside areas, including the island's old port, that are in close proximity to cliffs.

“These measures are precautionary, and authorities will remain vigilant,” Civil Protection Minister Vasilis Kikilias said late on Sunday following an emergency government meeting in Athens. “We urge citizens to strictly adhere to safety recommendations to minimise risk.”

While Greek experts say the quakes, many with magnitudes over 4.5, are not linked to Santorini’s volcano, they acknowledge that the pattern of seismic activity is cause for concern.

Government officials met with scientists throughout the weekend and on Monday to assess the situation, while schools were also ordered shut on the nearby islands of Amorgos, Anafi and Ios.

The frequency of the quakes, which continued throughout Sunday night and into Monday, has worried residents and visitors.

“I have never felt anything like this and with such frequency – an earthquake every 10 or 20 minutes. Everyone is anxious even if some of us hide it not to cause panic, but everyone is worried," said Michalis Gerontakis, who is also the director of the Santorini Philharmonic Orchestra.

“We came out yesterday and performed. Despite the earthquakes, the philharmonic performed for a religious occasion,” Gerontakis said. "When you are playing, you cannot feel the quakes but there were earthquakes when we were at the church. No one can knows what will happen. People can say whatever they like, but that has no value. You cannot contend with nature.”

Residents and visitors were advised to avoid large indoor gatherings and areas where rock slides could occur, while hotels were instructed to drain swimming pools to reduce potential building damage from an earthquake.

Fire service rescuers who arrived on the island on Sunday set up yellow tents as a staging area inside a basketball court next to the island's main hospital.

“We arrived last night, a 26-member team of rescuers and one rescue dog," said fire brigadier Ioannis Billias, adding that many residents, including entire families, spent the night in their cars.

Some residents and local workers headed to travel agents seeking plane or ferry tickets to leave the island.

“We’ve had earthquakes before but never anything like this. This feels different," said Nadia Benomar, a Moroccan tour guide who has lived on the island for 19 years. She bought a ferry ticket Monday for the nearby island of Naxos.

“I need to get away for a few days until things calm down,” she said.

Others said they were willing to take the risk. Restaurant worker Yiannis Fragiadakis had been away but said he returned to Santorini on Sunday despite the earthquakes.

“I wasn’t afraid. I know that people are really worried and are leaving, and when I got to the port it was really busy, it was like the summer," Fragiadakis said. "I plan to stay and hopefully the restaurant will start working (for the holiday season) in three weeks.” (AP)