A major 8.0 magnitude earthquake has hit the Solomon Islands, reportedly flattening three villages and killing four people.
It also caused small tsunami waves to lap Pacific coastlines and emergency sirens to blare evacuation warnings.
Solomon Islands Police Commissioner John Lansley said at least four people died.
Solomons officials reported two waves hit the western side of Santa Cruz Island, damaging about 50 homes and properties, said George Herming, a spokesman for the prime minister.
Australia's earthquake monitoring agency and the Pacific centre said the biggest tsunami wave measured was 91cm high, at Lata, on the main Santa Cruz island of Ndende.
Many villagers had moved to higher ground as a precaution, Herming said.
Vanuatu and New Caledonia also reported rising sea levels before a region-wide tsunami alert was lifted.
Sirens were heard in Fiji. "Chaos in the streets of Suva as everyone tries to avoid the tsunami!!" tweeted Ratu Nemani Tebana from the Fiji capital Suva.
The Pacific Tsunami Warning Centre cancelled its regional alert at 1450 AEDT, about two and a half hours after the quake struck.
The US Geological Survey said the quake hit the Santa Cruz Islands in Temotu province, which have been rocked by a series of strong tremors over the past week, at a shallow depth of 5.8 kilometres.
Temotu is the easternmost province of the Solomons, about a three-hour flight from the capital, Honiara. The region has a population of about 30,000.
Two powerful aftershocks of 6.4 and 6.6 magnitude were also recorded.
Locals in Honiara, 580 kilometres from the epicentre, said the quake was not felt there.
"The information we are getting is that some villages west and south of Lata along the coast have been destroyed, although we cannot confirm this yet," the director of nursing at Lata Hospital told AFP.
"There was continuous shaking in Lata but no damaged buildings here," he added.
The ABC quoted emergency service authorities in the Solomons as saying three villages were destroyed by the quake. Officials could not be reached for confirmation, with phone lines down.
Hospital director Augustine Bilve said patients were being evacuated to prepare for any injured from the villages along the coast.
"We were told that after the shaking, waves came to the villages. So far, we are waiting in Lata and are evacuating patients in case there are any casualties."
A staff member at the Solomons National Disaster Management Office said officials were concerned about Temotu.
Before it was lifted, the Pacific centre's tsunami warning was in effect for the Solomon Islands, Vanuatu, Nauru, Papua New Guinea, Tuvalu, New Caledonia, Kosrae, Fiji, Kiribati, and Wallis and Futuna.
In 2007, a tsunami following an 8.0-magnitude earthquake killed at least 52 people in the Solomons and left thousands homeless. The quake was so powerful it lifted an island and pushed out its shoreline by dozens of metres.
The Solomon Islands are part of the "Ring of Fire", a zone of tectonic activity around the Pacific Ocean that is subject to earthquakes and volcanic eruptions.