The US Geological Survey says the quake this evening was centered in the province of East New Britain, about 110 kilometres from the provincial capital, Kokopo.
The Pacific Tsunami Warning Center said hazardous tsunami waves were possible within 300 kilometres of the epicenter. It also said the epicenter was 61 kilometres deep. Shallower quakes typically have more damage potential.
Papua New Guinea sits on the Ring of Fire, the arc of seismic faults around the Pacific Ocean where earthquakes are common.