A tweet has been shared of cars crushed under buildings that were shaken in the earthquake.

Disasters Daily tweeted that: "Rescuers [are] trying to reach trapped people."

Vanuatu government websites were offline in the aftermath of the quake and phone numbers for the police and other public agencies did not connect.

Currently, the Vanuatu government website remains down.

Social media channels for the country's geohazards agency and the prime minister's office have not been updated.

A tweet has been shared of the damage caused by the earthquake in Vanuatu's capital of Port Vila.

The US, UK, French and NZ  Embassy has been damaged in the earthquake.

The US National Weather Service has updated its website to say there is no Tsunami warning, advisory, watch or threat for Vanuatu.

Trained Red Cross volunteers are on the ground in Port Vila ready to offer assistance.

Katie Greenwood, head of Asia Pacific Regional Office of the International Federation of Red Cross said the volunteers have "pre-positioned relief items".

Dan McGarry, a local journalist in Port Vila, said it was a "violent, high-frequency shake" that lasted for about 30 seconds.

He said there were sirens being heard around the capital.

Witnesses have reported major landslides near the capital.

The United States Tsunami Warning System said there was the threat of a tsunami after the quake.

"Tsunami waves have been observed," the Pacific Tsunami Warning Center said in a bulletin, predicting waves of up to 1 metre (about 3 feet) along some parts of Vanuatu's coastline

The Bureau of Meteorology said there was no tsunami threat to Australia.

Authorities are now monitoring for any sign of a tsunami.

Authorities are warning of a tsunami threat after a magnitude-7.4 earthquake struck Vanuatu.

The quake struck 37km from the capital, Port Vila at 12:53pm AEDT.

It struck at a depth of 10km, the United States Geological Survey said.