The temblors produced no tsunamis and there had been no reports of damage.
The U.S. Geological Survey said the larger quake, which occurred at 8:52 a.m.local time at a depth of 52 miles, was centered 27 miles east-southeast of Finschhafen, 86 miles east of Lae, 111 miles east-northeast of Wau and 198 miles north-northeast of Port Moresby.
The 4.8-magnitude quake occurred at at 8:11 a.m. at a depth of 40.8 miles, 37 miles southeast of Finschhafen, 92 miles east of Lae, 113 miles east-northeast of Wau and 190 miles north-northeast of Port Moresby.
Dulcie Logo of the Kokopo Village Resort told Radio New Zealand the bigger earthquake was short with a sharp jolt.
"It didn't do any damage, it just shook the place and everybody was awakened by the shake," Logo said.