A SHALLOW 7.4 earthquake struck off Vanuatu today, seismologists said, sparking a tsunami warning across the region.
The quake at 4.14am (3.14am AEST) hit at a depth of 36km, 214km north-west of Luganville, or 2070km north-east of Brisbane, according to the US Geological Survey.
The US issued a tsunami warning for areas of the South Pacific including the Solomon Islands, Vanuatu and New Caledonia.
The warning means coastlines near the epicentre could be subject to tidal waves within minutes.
But the warning will not be expanded to other areas of the Pacific unless new data shows a threat, USGS said.
"It is not known that a tsunami was generated," the Pacific Tsunami Warning Centre said. "This warning is based only on the earthquake evaluation.
"An earthquake of this size has the potential to generate a destructive tsunami that can strike coastlines in the region near the epicentre within minutes to hours.
"Authorities in the region should take appropriate action in response to this possibility. This centre will continue to monitor sea level gauges nearest the region and report if any tsunami wave activity is observed."
An 5.7-magnitude aftershock hit ten minutes later 35km under the seabed, 190km north-west of Luganville, Vanuatu's second-largest city.