A magnitude 6.1 earthquake struck off the coast of Vanuatu early Sunday, the US Geological Survey said, just days after a deadly 7.3-magnitude quake hit near the same island in the Pacific archipelago.
The nation's main island, Efate, is still reeling from the Tuesday quake, which killed 12 people as it toppled concrete buildings in the capital and set off landslides.
The latest quake Sunday occurred at a depth of 40 kilometres (25 miles) and was located some 30 kilometres west of the capital Port Vila.
Unlike the earlier quake, no tsunami alerts were immediately triggered by the latest temblor, which struck at 2:30 am (1530 GMT Saturday).
Mobile networks remained knocked out from earlier in the week, making outside contact with Vanuatu difficult early Sunday.
In addition to disrupted communications, the first quake has damaged water supplies and resulted in halted operations at the capital's main shipping port.
The South Pacific nation declared a seven-day state of emergency and a night-time curfew following the first quake, and had only announced Saturday it would lift a suspension on commercial flights, in an effort to restart its vital tourism industry.
Rescuers Friday said they had expanded their search for trapped survivors to "numerous places of collapse" beyond the capital.
Still searching
Australia and New Zealand this week dispatched more than 100 personnel, along with rescue gear, dogs and aid supplies, to help hunt for trapped survivors and make emergency repairs.
There were "several major collapse sites where buildings are fully pancaked", Australia's 69-strong rescue team leader Douglas May said in a video update provided by Canberra on Friday.
"Outside of that, there's a lot of smaller collapses around the place," he said.
"We're now starting to spread out to see whether there's further people trapped and further damage. And we've found numerous places of collapse east and west out of the city."
In Port Vila, rescuers have focused on two disaster areas from Tuesday's earthquake: a four-storey building housing a supermarket, hotel and garage in the north in which the ground floor was flattened, and a two-floor shopping block in the city centre that crumbled into a flat pile of concrete.
More than 1,000 people were displaced as a result of the first quake -- many now with other households or in evacuation centres, the latest UN report said, citing Vanuatu disaster management officials.
Vanuatu, an archipelago of some 320,000 inhabitants, sits in the Pacific's quake-prone Ring of Fire.
Tourism accounts for about a third of the country's economy, according to the Australia-Pacific Islands Business Council.