According to the USGS, the first quake with a 5.8-magnitude was registered at 14:33 GMT on Sunday (00:33 on Monday local time), with the epicenter located some 85 kilometers (53 miles) to the southwest of the town of Porgera at the depth of six kilometers.
Another tremor with a 6.0-magnitude occurred five hours later 112 kilometers to the southwest of Porgera. The epicenter was located at the depth of 10 kilometers.
There has been no information on victims or damages caused by the tremors.
Papua New Guinea is located in a seismically active zone known as the Ring of Fire and regularly suffer from powerful earthquakes.
In late February, the country was hit by the 7.5-magnitude earthquake with dozens of people having been killed.