Disaster relief agencies are scrambling to reach tsunami-hit villages in the Solomon Islands, warning the death toll following a powerful 8.0-magnitude quake is likely to rise.
Officials say six people are confirmed dead after Wednesday's quake generated a wave that swamped coastal communities on the island of Ndende in the eastern Solomons, triggering fears of a more widespread destructive tsunami.
Aid agency World Vision says some houses in the town of Venga were shifted 10 metres by the surge of water and 95 per cent of homes in Nela village were washed away.
"I'm currently walking through one community and I'm knee-deep in water," World Vision emergency coordinator Jeremiah Tabua said. "I can see a number of houses that have been swept away by the surge."
The Solomon Islands Red Cross said the remoteness of the disaster zone, more than 600km from the capital Honiara, was hindering relief efforts, with the island's airstrip closed due to debris on the runway.
Red Cross disaster manager Cameron Vudi says reconnaissance flights will be made over the island on Thursday to assess the scale of the damage but initial reports indicate at least 460 homes have been destroyed.
He says the death toll is likely to rise as reports come in from isolated communities.
"We're expecting changes. There are signs that there might be increases in the number of casualties," he told AFP.
"There are still reports coming in. Most of the reports are confined to areas that are accessible by road but there are a lot more communities that have been damaged."
He said boats with emergency supplies such as tarpaulins, fresh water and medical equipment would depart Honiara for Ndende on Thursday but were not expected to reach the stricken island until the weekend.
The US Geological Survey said the powerful quake struck at 0112 GMT (1212 AEDT) on Wednesday beneath the sea about 76km west of Lata, Ndende's main town, at a depth of 28.7km.
It was followed by dozens of strong aftershocks of up to 7.0 magnitude and the Hawaii-based Pacific Tsunami Warning Centre put several island nations on alert for two-and-a-half hours before declaring the threat had passed.
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.
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.
In December 2004, a 9.3-magnitude quake off Indonesia triggered a catastrophic tsunami that killed 226,000 people around the Indian Ocean.