The Pacific tsunami warning centre has cancelled its tsunami warning for New Zealand, while Civil Defence authorities said only a small wave was generated by Wednesday night's big Fiordland earthquake.
GNS Science upgraded its reading on Wednesday night for the quake to 7.8 magnitude, bringing it into line with international readings, TVNZ reports.
The earthquake, which was recorded at about 9:22 p.m. (09:22 GMT), was felt across Southland and Otago region. Local residents said the earthquake lasted several minutes.
A 6.1 magnitude aftershock was also reported at 9:41 p.m. (09:41 GMT).
The Hawaii-based Pacific Tsunami warning center has issued a non-expanding regional warning for a possible tsunami for part of the Pacific near the earthquake.
Local residents have been advised to keep listening to the radio.
According to Radio New Zealand Vince Cholewa of the Emergency Management Center said GNS scientists were working with their U.S. counterparts to reconcile measurements of the quake and the tsunami risk.
There were reports of cracks in buildings in the Tuatapere area, and power was out there for a short time.
There were also reports of items falling off a supermarket shelf in Queenstown and walls in Invercargill. It was also felt in Dunedin, United Press International reports.
Meanwhile Civil Defense spokesman Vince Cholewa told Reuters that "There was a small wave, but it was not damage causing ... people probably wouldn't have noticed it among the other waves," Reuters reports.