The quake hit about 67 km east of Kainantu and 80 kms north-west of Lae in the east of the country. It hit at 9:45am local time (23:45 GMT Saturday) and was felt around 500 km (310 miles) away in the capital of Port Moresby.
It was difficult to assess the extent of the damage immediately as the area struck by the earthquake is so remote.
However, earthquakes are common in PNG as the nation is located on the Pacific Ocean’s “Ring of Fire” where seismic activity is common due to friction between tectonic plates.
Although the PNG government has given no official death toll, the United Nations Office for the Coordination of Humanitarian Affairs (OCHA) in Asia and the Pacific said that four deaths had occurred.
OCHA’s PNG disaster management team reported on Twitter that one person had died in a landslide in Rai Coast, Madang while three others were buried in Wau, Morobe.
It added that although the airport was operational, the regional power grid, internet cables, and the regional highway were damaged.
Some people who were injured were airlifted for immediate medical treatment, they added.
On social media PNG residents shared images and videos of cracked roads, damaged buildings and cars, and items falling off supermarket shelves.
A United Nations report said that people had been injured by falling structures and debris.
He said: “My thoughts and prayers are with all those affected….
“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.”
Although the US Tsunami warning system sent out an alert after the quake it later confirmed that the danger had passed.
The Australian Bureau of Meteorology also confirmed that the antipodean country was not under threat.
In 2018 a quake measuring 7.5 on the Richter scale hit PNG’s mountainous highlands killing 100 people and damaging thousands of homes.