Not "newish" - Nadzab airstrip was built in the early 1940s due to the need for greater strip length and improved weather conditions.
The name Nadzab pre-dates the airstrip and was the original name of a Lutheran Mission Station established in the Nadzab area in 1910.
There are a number of non local names in the valley which probably date back to the German era pre 1918 e.g. Markham Valley, Leron Plains etc.