The death toll from an earthquake that struck Vanuatu on Tuesday has risen to 14, as search teams claw through piles of rubble in an attempt to locate survivors.

Two hundred others are being treated for injuries, with powerful aftershocks from the 7.3-magnitude tremor reported overnight.

The earthquake damaged buildings, including the embassies of the US, France, the UK and New Zealand. It also cut power and mobile services.

Vanuatu police say a seven-day state of emergency has been declared to limit the movement of the public while search and relief operations are underway.

Four of the fatalities died at hospital in the capital city of Port Vila, the government said. Six were from a landslide, while four were from a collapsed building, where the toll was expected to rise further.

An estimated 116,000 people could be affected by the worst impacts of the quake, the UN Office for the Coordination of Humanitarian Affairs said.

Neighbouring Australia will send teams to assist in the search and rescue effort, Deputy Prime Minister Richard Marles told ABC News on Wednesday.

Photos shared by Vanuatu Police on Facebook showed rescuers sifting through rubble by hand and crawling under the floors of collapsed buildings.

From the rubble of one three-storey building, rescuers heard the voices of at least three people, Vanuatu resident Michael Thompson told AFP news agency.

Thompson said rescuers used "everything we can get our hands on", including jack hammers, grinders and concrete saws, to rescue people.

The earthquake struck at 12:47 local time (01:47 GMT) on Tuesday and triggered a brief tsunami warning.

Vanuatu, a low-lying archipelago of some 80 islands in the South Pacific, is located west of Fiji and thousands of kilometres east of northern Australia.

The nation sits in a seismically active area, and is susceptible to frequent large earthquakes and other natural disasters.