An earthquake of 6.7 magnitude struck off the coast of the South Pacific nation of Vanuatu on Tuesday, prompting local authorities to warn outlying islands of possible tsunamis.
Job Esau, director of Vanuatu's National Disaster Management Office, said an alert had gone out on national radio, but there were no reports of damage or casualties.
"We have contacted the provinces by telephone," he told. "There has not been any damage caused to infrastructure."
The quake was recorded at 9:18 am local time (0348 IST), 77 kilometres east of Vanuatu's largest Island Santo, the US Geological Survey said.
Its depth was 149 kilometres below the seabed.
The reading was based on the open-ended Moment Magnitude scale, now used by US seismologists, which measures the area of the fault that ruptured and the total energy released.
Goescience Australia said an earthquake of that magnitude and depth would not have posed a tsunami risk.
"Generation of a tsunami would not be possible for a magnitude 6.7 event at 150 kilometres depth," said seismologist David Jepsen.
At least 654 people were killed in Indonesia last month when a 7.7-magnitude quake sent tsunamis crashing into the south coast of Java island.
On December 26, 2004 killer waves spawned by an earthquake off Indonesia swept across countries in the northern Indian Ocean, killing around 220,000 people.