At least 55 people have been confirmed dead and authorities fear the toll could exceed 100 from last week’s powerful earthquake in Papua New Guinea, as survivors faced more shaking from the strongest aftershock so far.

Southern Highlands governor William Powi said people were feeling traumatised from the disaster and ongoing aftershocks. The latest was a magnitude 6.7 quake that struck just after midnight local time, the strongest shake since last Monday’s deadly magnitude 7.5 quake that destroyed homes, triggered landslides and halted work at four oil and gas fields.

The central region where the quake struck is remote and undeveloped, and assessments about the scale of the damage and injuries have been slow to filter out. Powi said he did not know if the latest aftershock had caused more damage or injuries, but he said it had added to the distress people were feeling.

“It is beyond the capacity of the provincial government to cope with the magnitude of destruction and devastation,” Powi said. “Our people are traumatised and finding it difficult to cope.”

He said provincial authorities were trying to prioritise the greatest needs by getting people with severe injuries to medical centres and providing water and medicine. He said help from abroad and from local aid agencies was slowly coming in.

“It’s a mammoth task. Most of the feeder roads are washed away or covered with landslips. People’s livelihoods are devastated, their personal property is gone.”

Powi said 39 people had died in his province when families were crushed by their collapsing homes or buried by landslides. He said death reports were still coming in from remote places, and he feared the toll would rise to over 100.

A spokeswoman at the National Disaster Centre said the official death toll is currently estimated at between 55 and 75.

The US Geological Survey said Wednesday’s quake was centred 112km (70 miles) southwest of Porgera at a shallow depth of 10km (6 miles). Ten aftershocks in the hours since ranged between magnitude 4.7 and magnitude 5.2.

Papua New Guinea is home to 7 million people on the eastern half of the island of New Guinea. It sits on the Pacific’s “Ring of Fire”, the arc of seismic faults around the Pacific Ocean where most of the world’s earthquakes and volcanic activity occur.