A strong but shallow 6.8 magnitude earthquake rocked the northern coast of Papua New Guinea on Wednesday morning, but scientists immediately quelled off concerns of a possible tsunami aftermath in the Pacific.

According to the US Geological Survey, the seven kilometres deep quake struck at 0855 (AEST) on Wednesday, 19km east of the small town of Aitape on the Pacific nation's north coast.

Disaster emergency response teams however have yet to ascertain any casualties.

Chris McKee, the assistant director of the Geophysical Observatory in the capital, Port Moresby, believed residents may have immediately sought to go to higher ground as soon as the first earthquake jolt occurred, thus making immediate communication and coordination still not plausible.

Geoscience Australia estimated the exposure zone could affect some 60,000 people.

"This would include outlying local villages," Steve Tatham, Geoscience Australia seismologist, told AFP.

Although the Pacific Tsunami Warning Centre did not issue a destructive tsunami warning, it cautioned nearby nations to nevertheless be on alert as earthquakes of this size could sometimes create local tsunamis within 100km of the epicentre.

"Authorities in the region should be aware of this possibility and take appropriate action," the centre said.

"At this stage we have heard nothing about the effect but it is quite large and there would have been a high level of shaking," Mr Tatham said.

"There is the possibility of considerable damage. It certainly could bring buildings down."

It was only last Sunday that Papua New Guinea experienced its last earthquake, a 6.6-magnitude, which struck off Bougainville Island. There were no reports of damage or injuries.

Papua New Guinea is located on the Pacific "Ring of Fire," an arc of volcanoes and fault lines encircling the Pacific Basin, making it prone to seismic upheavals.