An earthquake has been felt widely across the North Island this morning.
The 5.1 magnitude quake was 167 km deep, centred 25 km south-east of Tokoroa, GNS said.
It struck at about 6.48am and has been felt in Hawke's Bay, Manawatu-Wanganui, Wellington and in the top of the South Island.
GNS seismologist John Ristau said the depth of the quake was probably the reason it was felt so widely.
"The earthquake starts off deep and the seismic waves travel up to the surface and by the time they reach the surface they spread out over a large area," he said.
"Whereas shallow earthquakes tend to be felt very strongly, but just close to where the earthquake happened."
At least 1500 people have reported to GNS that they felt the quake.
Others took to Twitter to describe what they felt.
Thanks for shaking me awake earth. Jerk. #eqnz— La Michelle (@smrtgirl) September 23, 2015
How do you know you are in Wellington? When you are woken by an earthquake that's how!— Wardrobe Flair (@WardrobeFlair) September 23, 2015
Used the earthquake wake up alarm this morning.— Bounder (@DawgBelly) September 23, 2015
My dog got up, looked out window, looked at me, came & sat next to me at my desk, then #eqnz arrived. small 1 here & now she's back asleep— Jane Thompson (@cheviotjane) September 23, 2015