A powerful earthquake with a magnitude of 7.5 struck off the Solomon Islands on Sunday night, hours after a 7.6 tremor, the US Geological Survey said.

A tsunami warning was issued by the Pacific Tsunami Warning Center for the Solomon Islands, Vanuatu and Papua New Guinea, but it later cancelled the alert for all three areas.

The USGS said the quake -- which it had initially assessed at 7.7 -- occurred at 11:36pm local time (1236 GMT) at a depth of 35 kilometres (22 miles), 111 kilometres south of Kirakira in the Solomon Islands.

It said the likelihood of casualties or damage was low.

A 7.6-magnitude quake had woken the residents of the Solomons capital Honiara early on Sunday.

It struck at 7:14am, about 300 kilometres from the capital, and was followed 10 minutes later by a 5.9-magnitude aftershock.

The US Geological Survey measured the undersea quake at around 29 kilometres deep.

Honiara resident Dorothy Wickham said the National Disaster Council was warning people to stay away from low-lying areas as the islands experienced high waves.

"People are moving away from the coasts and are going up into the hills, but I have not heard of any damage," she said.

The Intergovernmental Oceanographic Commission put out a tsunami warning for the Solomon Islands, Vanuatu and Papua New Guinea following the Sunday morning quake, but later cancelled the alert.

The Solomons were hit by flash floods 10 days ago which left more than 20 dead. Several more are still missing in Honiara after the city's main river burst its banks following days of heavy rain.

The Solomons are part of the "Ring of Fire", a zone of tectonic activity around the Pacific that is subject to frequent earthquakes and volcanic eruptions.

A 6.1-magnitude tremor hit the Solomons on Saturday and a powerful 7.1-magnitude earthquake and 6.7 aftershock struck off Papua New Guinea's Bougainville island on Friday, to the west of the Solomons.

In February last year, the Solomon Islands were hit by a major 8.0-magnitude quake that generated small but deadly tsunami waves which washed away houses and reached as far away as Japan.

In 2007, a tsunami following an 8.0-magnitude earthquake killed at least 52 people in the Solomons and left thousands homeless.

The quake lifted an entire island and pushed out its shoreline by dozens of metres.

7.1 quake hits off Papua New Guinea: USGS
Sydney, Australia (AFP) April 11, 2014 - A powerful 7.1-magnitude earthquake struck off Papua New Guinea on Friday and was followed by a 6.7-magnitude tremor, US officials said, but no Pacific-wide tsunami warning was sounded.

The US Geological Survey (USGS) said the first quake, originally put at 7.3 magnitude but later revised down, struck 57 kilometres (35 miles) off the town of Panguna on the remote and volcanic Bougainville island.

The second hit about an hour later 96 kilometres from Panguna, the USGS said, adding that both quakes had an estimated depth of about 50 kilometres.

Geoscience Australia estimated the first quake at 7.4 magnitude and said the tremor, which hit close to the neighbouring Solomon Islands, was believed to be in the "shallow" range.

"They would have gotten a strong shake across the island, and there's the possibility of some damage," David Jepsen from Geoscience Australia told AFP.

The Hawaii-based Pacific Tsunami Warning Center ruled out the threat of a Pacific-wide destructive tsunami after both quakes but Jepsen cautioned that there was a "possibility of a local tsunami" in PNG.

Chris McKee from the PNG Geophysical Observatory said officials had not yet been able to make contact with those on remote and isolated Bougainville island.

"We haven't been able to determine whether a tsunami was generated," he told AFP.

Quakes of such magnitude are common in the island nation, which sits on the so-called Pacific "Ring of Fire", a hotspot for seismic activity due to friction between tectonic plates.

In October, a 7.1-magnitude quake struck in the same area -- around 65 kilometres west of Panguna.

Last year in February the remote town of Lata in the Solomons was hit by a devastating tsunami after an 8.0-magnitude earthquake. The tsunami left at least 10 people dead, destroyed hundreds of homes and left thousands of people homeless.

In 2007 a tsunami following an 8.0-magnitude earthquake killed at least 52 people in the Solomons and left thousands homeless.