A POWERFUL 7.3 magnitude earthquake struck off Vanuatu in the Pacific Ocean, but no tsunami threat was detected, seismologists said.

The quake hit at a depth of 131km, about 335km from the capital Port Vila, the United States Geological Survey said, meaning it had less impact on the surface than if it had been shallower.

There were no immediate reports of damage or injuries.

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Mag 7.5, Vanuatu Islands. 21 Oct 2015, 08:52 (AEDT). Lat, Long: -14.86, -167.26. Depth 125km. Info is preliminary — EarthquakesGA (@EarthquakesGA) October 20, 2015

“Based on all available data a destructive Pacific-wide tsunami is not expected,” the Pacific Tsunami Warning Centre said.

Government agency Geoscience Australia said the general threshold for an undersea earthquake that could potentially generate a tsunami was a magnitude of 6.5 and a depth of 100km.

“It was probably felt but unlikely to cause any damage,” seismologist Dan Jackson told AFP, adding that there had been 27 tremors above magnitude 7.0 around Vanuatu over the past 20 years.

“Quakes like this are a common occurrence over there. The region around Vanuatu and the Solomon islands is the most seismic in the world.”

Massive 7.3 Earthquake just shook Vanuatu in Oceania pic.twitter.com/4rLpGfD8BS — Danville/SR Updates (@DanvilleSR_News) October 20, 2015

Vanuatu’s National Disaster Management Office Director Shadrack Welegtabit said there were no initial reports of damage or injuries but he was still awaiting information from some of the outer islands closer to the epicenter.

Vanuatu is part of the “Ring of Fire”, a zone of tectonic activity around the Pacific that is subject to frequent earthquakes and volcanic eruptions.

The South Pacific island was jolted by a 6.8-magnitude tremor in late January and another of 6.5 in February, but there were no reports of damage.