SYDNEY (AFP) - A 7.0-magnitude earthquake struck off the coast of the Solomon Islands on Saturday, the US Geological Survey (USGS) said, but the threat of a Pacific tsunami in the tremor-prone region was thought to have mostly passed.

The shallow tremor was centred about 78 km west-northwest of Lata in the Solomon Islands and about 583 km from the capital Honiara, it said, after revising it down from an initial estimate of 7.5.

Geoscience Australia, which estimated the quake at 7.3-magnitude, said it was possible that a local tsunami could have been generated within several hundred kilometres of the jolt.

But the Hawaii-based Pacific Tsunami Warning Centre, which said its estimate on the quake's size was 6.9, said that based on all data available "the tsunami threat from this earthquake has now mostly passed".

"Minor sea level fluctuations of up to 0.3 m above and below the normal tide may continue over the next few hours," it added.

The Solomons are part of the Pacific "Ring of Fire", a zone of tectonic activity known for its frequent earthquakes and volcanic eruptions.

"It's large but it's not the largest," Geoscience's Eddie Leask told AFP of Saturday's quake. "The main risk is obviously the earthquake shaking. This is an area which regularly experiences these throughout history."

In 2013, the Solomons were hit by a tsunami after an 8.0-magnitude quake, leaving at least 10 people dead and thousands homeless after buildings were destroyed