A strong 7.0 magnitude earthquake struck the Solomon Islands on Tuesday, with eyewitnesses reporting violent shaking that hurled televisions and other items to the ground.
A tsunami warning was issued for an area of the Solomons coast within 300 kilometres of the epicentre.
People were advised to move to higher ground immediately, said a spokesman for the Solomon Islands' prime minister.
"This was a big one," Joy Nisha, a receptionist with the Heritage Park Hotel in the capital Honiara, told AFP. "Some of the things in the hotel fell. Everyone seems OK, but panicky."
An AFP reporter in the capital said the shaking lasted for around 20 seconds. Power was out in some areas of the city and people were leaving their offices and fleeing to higher ground.
The USGS revised the earthquake's magnitude down from an initial 7.3.
The earthquake struck at a relatively shallow depth of 10 kilometres, just off the southwest coast of Guadalcanal island.
"Tsunami waves reaching 0.3 to 1 metres above the tide level are possible for some coasts" in the area, a UN-backed Pacific warning system said. Some coastal regions of Papua New Guinea and Vanuatu were also put on alert for tsunami waves of up to 30 centimetres.
According to UN data, about 20,000 people live within 50 kilometres of the epicentre. The Solomons is a sprawling archipelago in the southwest of the Pacific Ocean and home to about 800,000 people.
US tsunami warning system later reported the threat of a tsunami had passed.