SYDNEY: Authorities in the Solomon Islands said no tsunami warning would be issued after two powerful earthquakes struck on Tuesday, damaging Australia's embassy, the airport and shopping malls and triggering power cuts in the capital, Honiara.

The first quake hit offshore at a depth of 15 km (9 miles), about 16 km southwest of the area of Malango, said the United States Geological Survey which initially put its magnitude at 7.3 before revising it down to magnitude 7.0.

A second quake, with a magnitude of 6.0, struck nearby 30 minutes later.

"We have sent a chopper up to fly over, to verify the scope and scale of damage," Brian Tomu, a public affairs official with the National Disaster Management Office, told Reuters by telephone.

The disaster authority's focus was Guadalcanal island, where Honiara is located, and nearest to the epicentre, he said.

People rushed out of offices in panic, seeking higher ground in the aftermath of the large earthquake, he said.

"There are no known injuries but the roof of the High Commission annex has collapsed, which would point to likely damage throughout the city," Australian Prime Minister Anthony Albanese told parliament.

Honiara International Airport suffered damage to its ceiling but the building was intact, a Solomon Islands Airline worker at the airport told Reuters by phone.

Aftershocks continue to be felt, he said, declining to be named as he is not authorised to speak publicly. Airport staff would continue working but the damaged section of the airport terminal was closed to passengers.

The Solomon Times newspaper reported power had been cut for most of Honiara, as preliminary assessments of damage to power lines are made.

The Solomon Islands Meteorological Service said there was no tsunami threat, but warned about unusual sea currents.

"People are also advised to be vigilant as aftershocks are expected to continue," it said on social media.

The meteorological service's director, David Hiriasia, told Reuters the power outage had delayed its advisory.

"We could not access information as fast as we would have wanted to run our threat analysis," he said, adding "we have not accessed our office building yet".

The Solomon Islands Broadcasting Corporation said on Facebook that all radio services had gone off the air.