UN Office for the Coordination of Humanitarian Affairs says one third of the population affected by a 7.3 earthquake.

Rescuers in Vanuatu are racing to find survivors of a powerful earthquake that killed at least 14 people in the Pacific island nation.

The 7.3 magnitude earthquake that struck the capital Port Vila on Tuesday destroyed buildings, triggered landslides and wiped out power and telecommunications infrastructure.

Katie Greenwood, the Asia-Pacific head of the International Federation of Red Cross and Red Crescent Societies, said on Wednesday that authorities had reported 14 confirmed deaths with 200 others being treated for injuries at Port Vila's main hospital.

Dan McGarry, a Canadian-born journalist who has lived in Vanuatu for more than 20 years, said it was a "reasonable expectation" that the death toll would rise further.

"I'm concerned that it's going to go up and the government expects the casualty rate to go up, if not the death toll," McGarry told Al Jazeera.

McGarry said that rescuers are looking for people who may be trapped under rubble or debris.

“We also have people who may have been trapped under a very large landslide near our international shipping terminal. We know that six deaths have been confirmed in that location so far," he said.

Australia and New Zealand announced that medical and rescue teams would be deployed from Wednesday to provide assistance.

"Australia stands with the people of Vanuatu after yesterday's devastating earthquake. Our deepest sympathies go out to the people of that wonderful, beautiful country, especially after the tragic loss of life there," Australian Treasurer Jim Chalmers said at a news conference on Wednesday.

"We know from early reports that quite significant damage has occurred there, and at the request of the Vanuatu government, we are deploying immediate assistance today."

The UN Office for the Coordination of Humanitarian Affairs said it estimated that about one-third of the archipelago's population of about 335,000 people had been affected by the worst effects of the earthquake.

"Telecommunications continue to be disrupted, affecting the timeliness of field reports from remote areas," the UN office said in a situation update.

"Access to the airport and water port is severely restricted due to road damage. Key immediate needs include healthcare support, shelter, access to clean water and the restoration of emergency communications.”

Michael Thompson, an Australian national who runs a zip-line adventure business in Vanuatu, said in a Facebook post that he had helped with rescue efforts and that three people had been found alive in the rubble overnight.

"Incredible display of bravery with people entering confined spaces to perform rescues," Thompson wrote.

A complex that houses the diplomatic missions of Britain, France, New Zealand and the United States is among the buildings that suffered severe damage, with part of the structure collapsing and leveling the first floor.

McGarry said the toll of the disaster will be felt by almost everyone in the archipelago because of its close-knit community.

"Everyone knows everyone, so we really feel the human toll very heavily here. Maybe more than other places,” McGarry said.

However, McGarry said people in Vanuatu had extensive experience of natural disasters such as cyclones and were largely calm despite the human toll.

"The mood here was generally very positive despite the human toll. People are very cooperative, they're patient with each other," McGarry said.

"Vanuatu society still has a very strong spirit of cooperation," he added.