A 7.6-magnitude earthquake rattled Papua New Guinea on Sunday, damaging buildings, triggering landslides and killing at least five people, with several more severely injured.
Residents in northern towns near the epicentre reported intense shaking mid-morning, with cracks appearing in roads and the cladding of buildings.
Local member of parliament Kessy Sawang said at least two people had died in remote mountain villages, with four others airlifted to hospital in critical condition.
"There has been widespread damage," she said.
In nearby Wau, Koranga Alluvial Mining said three miners had been buried alive.
There are limited communications in the area, few government resources and very few paved roads, making assessment and rescue efforts difficult.
Small aviation companies and missionary groups were involved in airlifting some of the injured across the rugged jungle landscape.
"It's very difficult, the terrain, the weather. It's challenging," said Nellie Pumai of Manolos Aviation, which had transported one person out and was trying to return.
In the eastern highland town of Goroka, photographs showed window awnings falling off the crack-riven walls of the local university.
Hivi Apokore, a worker at the Jais Aben Resort near Madang on the north coast of Papua New Guinea, said the tremor was "very strong".
"Everything was like sitting on a sea — just floating."
The quake was felt as far away as the capital Port Moresby, about 480 kilometres away.
The US Geological Survey initially issued a tsunami warning for nearby coastal areas, but subsequently said the threat had passed.
Regardless, residents of coastal areas fled for higher ground after reporting that the sea level had suddenly dropped.
Prime Minister James Marape urged people to remain cautious.
Mr Marape said several regions had been affected but that the scale of damage and injuries was unknown.
"National and provincial disaster agencies, as well as leaders, have been asked to assess the damage and injuries to people and attend to these as soon as possible."
State-backed communications firm DataCo said it was experiencing "multiple service disruptions" to the operation of a domestic undersea communications cable as well as the PIPE Pacific Cable 1 that runs from Sydney to Guam.
The quake struck about 67km from the Eastern Highlands town of Kainantu at a depth of 61km, the US Geological Survey said.
Earlier on Sunday, the US Geological Survey also reported two strong earthquakes in the remote Mentawai Islands off the western coast of Indonesia's Sumatra island.
A 6-magnitude earthquake struck at a depth of 20km at about 6.10am local time (2.10am UAE), closely followed by a 5.7-magnitude quake at a depth of 10km minutes later.
There were no immediate reports of casualties or damage, but the tremor sent residents on the islands fleeing to evacuation centres set up last week following another earthquake.
The quake was also felt in the city of Padang, the capital of Western Sumatra province, where residents left their homes after the tremor shook buildings.
Papua New Guinea and Indonesia sit on the Pacific "Ring of Fire", causing them to experience frequent earthquakes.
In 2004, a 9.1-magnitude quake off the western coast of Sumatra island triggered a tsunami that killed 220,000 throughout the region, including about 170,000 in the country.