A powerful 7.2 magnitude earthquake struck near the Solomon Islands in the western Pacific early on Monday, the second quake in less than an hour, the US Geological Survey said.
Earlier, a strong, 6.5 magnitude earthquake struck near the Solomon Islands in the western Pacific.
No tsunami alert was immediately issued.
But the Pacific Tsunami Warning Centre said: "Earthquakes of this size sometimes generate local tsunamis that can be destructive along coasts located within a few hundred kilometres (miles) of the earthquake epicentre."
The preliminary USGS report placed the epicentre of the quake 143km south-southeast of Gizo, in the Solomon Islands, and 309km west-northwest of Honiara, at a depth of 10km.
No major tsunami expected
The US National Oceanic and Atmospheric Administration said no tsunami was expected.
Geoscience Australia said the quake was probably about 80 kilometres from the nearest land, and could cause a local tsunami but that it was unlikely to be a major wave.
"It's a big earthquake but it's probably not going to cause a large regional tsunami," Geoscience Australia seismologist Clive Collins said.
Collins said a local tsunami was possible but there had been no reports of damage as yet and these were very difficult to predict.
"I don't think there's any problem but we don't any information as yet," he told AFP.
