GeoNet explained: "This quake likely occurred in the Pacific plate, which dives (subducts) under the Australian plate. Most of the quake's energy travels up and along the plate to the surface."
One Wainuiomata resident described the quake as "a little wiggle...pause then bang"
Wellington lawyer Felix Geiringer said on Twitter that the quake was felt in the capital as "two distinct waves".
On Thursday night, a magnitude 3.3 earthquake was recorded 10km east of Christchurch, at a depth of 7km.
The central North Island was rattled by a magnitude 5.9 quake late last month, that struck 30km south-west of Taumarunui and was recorded at a depth of 210km.
No damage was reported.