UPDATE: Tuesday, May 5, 2:30 p.m. AEST: The tsunami threat has mainly passed, the Pacific Tsunami Warning Center reported. Port Moresby Observatory noted some tsunami oscillations in the Rabaul Harbor.
A powerful earthquake rattled the South Pacific island nation of Papua New Guinea on Tuesday, and officials warned that a local tsunami was possible.
The 7.4-magnitude quake struck about 130 kilometers (80 miles) south of the town of Kokopo in northeastern Papua New Guinea, at a depth of 63 kilometers (40 miles), the U.S. Geological Survey reported, downgrading its original estimate that the quake was magnitude 7.5 and 10 kilometers (6 miles) deep.
The Pacific Tsunami Warning Center said tsunami waves of up to 1 meter (3 feet) were possible within 300 kilometers (186 miles) of the epicenter.
There were no immediate reports of waves being seen and no reports of damage, said Chris McKee, assistant director Geophysical Observatory in the capital, Port Moresby.
"The earthquake is offshore and the nearby land areas are fairly sparsely populated," McKee said.
The National Disaster Center also had not received any reports of damage, said acting director Martin Mose.
"We're just sending a message now to the area for villages along the coast to take extra precautions in case a tsunami is generated," he said.
Tuesday's quake was centered in the same area as two earthquakes that rocked Papua New Guinea last week. Neither of those quakes caused damage or generated a tsunami, but they were slightly lower in strength than Tuesday's.
Papua New Guinea sits on the Ring of Fire, the arc of seismic faults around the Pacific Ocean where earthquakes are common.