Last night's earthquake near Dunedin was the largest in the area for more than 40 years, GNS Science says.
The 4.7 magnitude quake struck at 11:17pm about 30 kms inland from Dunedin, in the Lee Stream area inland from Mosgiel.
The quake was shallow, at only 5 km, and felt widely across New Zealand.
Local people say it was a short, sharp bang, but no damage has been reported.
Seismologist at GNS Science, Caroline Holden, said the quake was the largest in the Dunedin area since a 4.9 in the same area which struck in 1974.
Dr Holden said there was also a smaller one of magnitude 4.1 last October in the same place.
Publican of the nearby Clarks Junction hotel, Adrian Bardrick, said the quake was the largest one he had ever experienced.
However, Mr Bardrick said it was very quick, shaking the pub's bottles for a few seconds and then going away.
"We were cleaning up after some rugby boys, and I thought it might have been their bus hitting the pub, but they didn't have one," he said.