First Australian crews en route to Vanuatu to assist rescuers after ...

The first Australian relief flight carrying supplies and personnel is en route to Vanuatu where rescuers are searching for bodies underneath rubble in the wake of a 7.4-magnitude earthquake.

Follow all the updates on the Vanuatu earthquake in our live blog

At least 14 people have been killed and more than 200 people are being treated in hospital after the earthquake struck on Tuesday, flattening buildings, damaging the hospital and causing landslides.

A second tremor, a magnitude-6 earthquake, was reported on Wednesday shortly before a seven-day state of emergency was declared by Vanuatu's caretaker Prime Minister Charlot Salwai.

The confirmed deaths include four in the capital Port Vila's hospital, six in a landslide, and four in a collapsed building where the toll is expected to rise further, the Pacific nation's government has said in a disaster update obtained by AFP.

A Royal Australian Air Force C-17 plane loaded with supplies and personnel left the RAAF Base Amberley, west of Brisbane, on Wednesday afternoon.

Urban search and rescue teams from Queensland's Fire and Rescue service are onboard and are tasked with assisting local crews in searching the rubble in Port Vila and surrounding areas.

Rescuers have worked through the night trying to reach people under the rubble. (ABC News: Lillyrose Welwel)

Treasurer Jim Chalmers said an additional two flights were planned to leave for Vanuatu on Wednesday, with the timing to be confirmed based on runway access at Port Vila.

He said the first assistance crews headed to Port Vila would assist with the most pressing needs.

"I really wanted to thank and acknowledge those Australian first responders who are leaving Australia today to help the people of Vanuatu after these tragic events," he said.

"I also wanted to make clear this is just our initial response. Our expectation is more help will be requested and more help will be provided.

A second flight would depart from Fairbairn with urban search and rescue personnel from Fire and Rescue NSW, Australian Federal Police, and a Department of Foreign Affairs and Trade (DFAT) crisis response team, Mr Chalmers said.

A further flight will depart from Darwin with an Australian medical assistance team (AUSMAT) deployed through the National Critical Care and Trauma Response Centre.

Mr Chalmers said the crews' task would be made harder due to the pressure the hospital in Port Villa was under and the damage it had suffered in the earthquakes.

The tremor that struck off Vanuatu caused "major structural damage" in at least 10 buildings in Port Vila including the main hospital, a large collapsed shop, and diplomatic missions including the US embassy building, according to the report from the country's National Disaster Management Office.

Three bridges and two power lines were also damaged, the report said.

Two major water reserves supplying Port Vila had been "totally destroyed and will need reconstruction", the government said.

The water network was still being assessed.

"With so many buildings down, it's really important that we get those search and rescue crews in as soon as we can," Mr Chalmers said.

Douglas May says his team is among the most capable in the world to respond to this kind of job. (ABC News: Ian Cutmore)

"Australia and Vanuatu share a very deep, enduring partnership.

"We are family and we will be there for them in their time of need."

Douglas May, the chief superintendent and task force leader of the disaster assistance response, said the crews were expecting to be "overwhelmed with work" when they arrived.

He said the people on the ground were doing their best but "they are very much looking forward to us arriving".

There have been reports of people missing and trapped in collapsed buildings.

"We've been in contact with people who have been on the ground rescuing … We know that … they have numerous sites with lives rescues," he said.

"We expect as soon as we get there, we will be rescuing known live victims."

The UN Office for the Coordination of Humanitarian Affairs estimated 116,000 people — about one-third of the country's population — had been affected by the earthquake.

Mr May said the team was among the most capable in the world to respond to this kind of job.

Douglas May says responding to such as disaster is "not something a small island nation can do easily". (ABC News: Ian Cutmore)

"It takes a lot to put together a team of this size and capability … and it's not something a small island nation can do easily," he said.

"[Local teams] are overwhelmed to manage this kind of collapse, big heavy, concrete building collapses … they are doing their best but they are looking forward to us arriving.

"Ultimately, we know there are lives to be saved … so that is the first priority, and after that it'll be helping to locate the deceased, and then it'll be providing services like water purification."

A seasonal worker named Valerie has been identified as one of the 14 people who have lost their life in the earthquake.

Rodney Prestia, the CEO of labour-hire company ICOMPLY, told the ABC he had confirmed her death with the family.

Valerie completed two seasons working in Australia. (Facebook: ICOMPLY)

Valerie had just completed her second season working in Australia and she flew home just three days ago.

"We're really devastated," Mr Prestia said.

"She's an amazing girl."

A Vanuatu cricket team playing in this week's grand final of the Stanthorpe competition has said that if it wins the tournament it will donate the money to Valerie's young son.

Frantic rescue efforts got underway after the earthquake hit, and rescuers worked through the night, trying to reach people screaming for help from under the rubble.

The secretary-general of the Vanuatu Red Cross Society said the earthquake death toll was expected to rise because there were still bodies to be recovered.

Earlier on Wednesday morning, the humanitarian organisation had updated the death toll in Vanuatu to 14.

"There's several numbers going around," Dickinson Tevi told ABC News Channel.

"I haven't had the chance to check on the [latest] numbers but I know that we still have people trapped under the debris or in a landslide.

"So the number should be expected to increase anyway."

Mr Tevi said the Red Cross Society had deployed volunteers to assist the central hospital and to assess the extent of the damage around the island.

"One challenge at the moment is identifying the corpses in the hospital … another challenge [is] some of the corpses are not easy to identify," he said.

ABC/wires