Rescue workers have had to grapple with landslides, blocked roads and downed power and communications to reach isolated villages after the 7.5-magnitude quake struck on February 26 in the Pacific nation's mountainous interior.
More than 100 people were killed, many more remain missing and thousands were injured, Prime Minister Peter O'Neill said, while survivors have had to endure strong aftershocks.
He added late Sunday that food and water were being airlifted to remote areas via Australian Defence Force C130 aircraft and Chinook helicopters.
The influx of supplies came as the nation's emergency controller, Bill Hamblin, who is leading the government's relief effort, described emotional scenes as aid workers flew above destroyed communities in the Southern and Hela provinces.
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"You can see mile after mile of ridges that have collapsed," Hamblin told PNG's Post-Courier newspaper.
"Anybody or anything that was down the valley was taken away and in fact one valley we saw a village that was left with one tin shed and the rest were buried."
He spoke of the fear that would have gripped villagers living on top of ridges as mountains slid away, and of others at the bottom of slopes with "nowhere to run" as avalanches came down.
"These things make you cry when you look at it but look we can't keep crying ... we have to get in and help the people survive as much as we can," he said.
Hamblin said the relief team were being helped by logistics experts from the United Nations who had coordinated similar efforts in Africa and the Middle East.