The Australian Broadcasting Corporation reported that the 6.0 aftershock hit the region at 6am caused a landslide that buried people in the small village of Huya.
Three aftershocks stronger than magnitude-5, including the magnitude-6 earthquake, shook the Southern Highlands, about 600km north-west of the capital Port Moresby, the US Geological Survey said.
Before the aftershocks this week, 16 deaths in Hela Province and 37 in Southern Highlands Province were recorded with a further 25 unconfirmed deaths following the February 26 earthquake.
This brings the total death toll to a possible 89 people.
With limited official reporting on the aftermath of the 7.5 earthquake, private companies and blog entries are about the only accounts upon which the extent of death and destruction can be based.
Blogger Sylvester Gawi said that local community leaders have taken charge of care centres in the Southern Highlands province as they await food, clothing and other relief supplies to be delivered.
Acting Southern Highlands Provincial Administrator Thomas Eluh says six care centres have been set up around the province by locals.
Road links into most of the affected villages have been blocked by debris from landslips piling up. Some sections of the roads were badly damaged by the movement from the earthquake.
Police from the Mobile Squad (MS 10) based in Mendi have been grounded in the last 24 hours after their fuel supply tanks were also damaged by the earthquake, Gawi reported.
Most shops and fuel stations have been reportedly closed following damages from Monday's earthquake and the aftershocks that are constant in the province.
The Agiru Centre which houses the provincial administration has also reported damages to its offices and equipment and has been condemned by authorities. The provincial administrator and the disaster team are now operating out of the provincial police command in Mendi.
The Mendi School of Nursing was one of the institutions visited by Gawi, who report that most of its buildings destroyed by the earthquake.
In Hela, a total of 16 deaths have been confirmed by the Hela Provincial Hospital in Tari. More casualties are expected to be reported in the coming days as volunteers are dispatched to gather reports.
Tari-Pori MP and Finance Minister James Marape says about 40% of Papua New Guinea's revenue will be affected if the PNG LNG Hides gas conditioning plant shuts down. Marape says the government is confident that this won't really affect the budgetary allocation for 2018.
The provincial disaster response team in Hela is also working together to address the situation.
The national government has committed K450 million towards disaster relief. The disaster committee has made allocations for the initial K100 million.
K40 million will be spent to fix the road infrastructures damaged by the earthquake so that affected areas are accessible for relief supplies to be delivered. K10 million will be used to assist schools and education institutions buildings damaged by the disaster and another K10 million for health services. K23 million has been set aside for transport, logistical support and other areas to provide relief assistance.
The remaining K350 million will also be expended on the same purposes once assessment reports of the extent of the damages are confirmed and brought to the disaster team's attention.