A magnitude 6.7 earthquake rattled northeastern Papua New Guinea on Saturday, the United States Geological Survey said, disrupting power grids and plunging coastal communities into darkness.
The strong quake had a depth of 53 kilometres (33 miles) and hit at around 7:30 pm (0830 GMT) with the epicentre about 56 kilometres southeast of the coastal town of Madang, the USGS added.
An aftershock of equal magnitude hit off the coast of Madang minutes later, the USGS said, although no tsunami threat was detected by monitors.
The tremors were strong enough in Madang -- a settlement of about 27,000 people known for its scuba diving -- to knock some people off their feet.
Residents said the quake had taken out electricity and the extent of any damage would not be clear until first light on Sunday morning.
"We've had some of our staff falling down to the ground," a receptionist at the Madang Resort told AFP.
"The power just went down, we had to turn on the hotel generator. Tomorrow we will get the bigger picture."
Madang Lodge receptionist Jennifer Auto told AFP they had "experienced some damage" but so far "nothing bad".
The region was badly damaged by a 7.6-magnitude earthquake that struck in September last year, causing more than 400 homes to collapse across the broader Madang province.
Ring of fire
Earthquakes are common in Papua New Guinea, which sits on top of the seismic "Ring of Fire" -- an arc of intense tectonic activity that stretches through Southeast Asia and across the Pacific basin.
Although they seldom cause widespread damage in Papua New Guinea's sparsely populated jungle highlands, they can trigger destructive landslides.
At least seven people were killed in April this year when a 7.0-magnitude quake hit a jungle-clad area in the Pacific island nation's interior.
About 180 homes were destroyed in the heavily rainforested Karawari area, near the quake's epicentre.
In September last year, 10 people were killed when a 7.6-magnitude earthquake levelled hundreds of homes, split roads and caused power outages across the rugged north of the country.
It was the largest quake to rock Papua New Guinea since 2018, when almost 150 people were killed following a shallow 7.5-magnitude tremor in Hela province.
Many of Papua New Guinea's nine million citizens live outside major towns and cities, where the difficult terrain and lack of sealed roads can seriously hamstring search-and-rescue efforts.