Vanuatu's deadly magnitude-7.3 earthquake has forced 1,700 people from their homes, with many still sleeping out in the open as weather forecasts predict heavy rain will hit Port Vila on Christmas Day.

More than 1,200 people are sheltering in evacuation centres, while others are staying in other temporary accommodation, according to the United Nations' Office for the Coordination of Humanitarian Affairs.

"Many people are scared to go back to their homes because the structures are not safe and they're damaged and the tremors keep coming," acting Country Director for Save the Children, Lavinia Mahit, said.

With 12 people confirmed dead and many still missing after last Tuesday's quake, the Vanuatu Meteorology and Geohazards Department on Monday warned severe weather risked causing flooding along coastal areas and rivers, flash floods, and landslides around Efate.

Vanuatu's National Disaster Management Office posted on social media urging people to act safely as severe weather hit the country.

"As we get ready for Christmas, we must think carefully also about making sure that our families are always safe," it said.

People are evacuating the Mele area north-west of Port Vila due to a major flooding risk.

Rain is expected from Monday afternoon, increasing to heavy rainfall on Wednesday.

However, Australia's Bureau of Meteorology said a tropical low over the Coral Sea had only a very low chance of developing into a tropical cyclone on Monday and Tuesday.

Nearly 1,000 Australians have been repatriated on RAAF flights and commercial flights since Wednesday last week.

After flying about 700 Australians to Brisbane over 10 flights, no further RAAF repatriation flights are scheduled as Port Vila's airport reopened to commercial flights including from Qantas, Virgin Australia and Jetstar on Sunday.

About 300 passengers, including Australians, returned to Australia from Vanuatu on Sunday on commercial flights.

Vanuatu Tourism Office chief executive Adela Issachar Aru on Monday afternoon said more would return home that day on commercial flights.

Australia's Department of Foreign Affairs and Trade also said 150 ni-Vanuatu Pacific Australia Labour Mobility Scheme workers had returned to Vanuatu on Sunday after being unable to reach their homes and families following the earthquake.

Ms Aru said 40 per cent of tourism operators in Efate were fully operational and another 19 per cent were partially operational.

As Vanuatu approaches one week since the disaster struck, medical services remain stretched and essential services are still being reconnected across the city.

Port Vila Central Hospital has treated 210 injured and Australian medical teams are helping with the disaster response.

Port Vila is still reconnecting essential services after the quake knocked out water, electricity and telecommunications.

Utility company UNELCO on Sunday said 75 per cent of the city's water services had been restored, and about 70 per cent of the electricity network had returned.

Residents were still being advised to boil water.

But Save the Children's Lavinia Mahit said water supply remained intermittent in some parts while repairs continued.

"We urgently need safe drinking water and jerry cans," she said.

Ms Mahit also raised concerns about the longer-term mental health impact of the natural disaster.

"There are a lot of people traumatised and especially kids. Along with the basics of survival, Save the Children is concerned for the kids and young people, they're the most vulnerable," Ms Mahit said.

"We're concerned the ongoing traumas are causing anxiety."

Much of the city's CBD remains closed to the public as emergency services and international search and rescue crews clean up debris following the natural disaster.

With VBTC