A tsunami warning was issued tonight after a major earthquake measuring 7.8 struck Fiordland, followed by a large aftershock.
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There were no immediate reports of damage throughout the region but power was off for five minutes in parts of Te Anau and power was cut to some parts of Invercargill.
Power lines came down in Matua Rd, Otatara. Businesses, such as supermarkets, reported stock coming off shelves.
The Deep Cove Hostel manager and his wife, who are based at Doubtful Sound, said the quake was so severe they hid under a table.
The manager reported loud bangs in the area which might indicate slips and he heard water "swooshing loudly" in the sound.
GNS Science reported the first quake struck at 9.22pm, centred 100km southwest of Te Anau and was 12 kilometres deep. It was initially reported as measuring 6.6 on the Richter scale but this was later upgraded to 7.8. It was felt strongly by residents in Invercargill, Dunedin, Timaru and as far north as New Plymouth.
An aftershock measuring 6.1 and five kilometres deep also struck 150 km west of Tuatapere at 9.41pm, according to GNS Science. It was also felt in the lower North Island.
The Pacific tsunami warning centre has cancelled its earlier tsunami warning for New Zealand, while Civil Defence authorities said only a small wave was generated by tonight's big Fiordland earthquake.
Group Controller Neil Cruickshank said that the emergency operations centre was monitoring the situation in Bluff, through people and recording equipment based there.
A tsunami warning had been issued and Southland Civil Defence Emergency Management had monitored sea levels through people and equipment stationed at Bluff.
A 17cm wave had been detected at Jackson Bay on the West Coast and the tsunami warning had subsequently been cancelled, he said.
Mr Cruickshank said it was believed the epicentre was a considerable distance from any township.
The Hawaii centre cancelled its alert just before 11pm.
An Invercargill man said his flat started shaking and he jumped under a table for safety. ''I was crapping myself,'' he said.
Another woman in the city said her children started screaming. ''We just told them it was like a ride.''
In Tuatapere, a Waiau Hotel patron said a ute parked outside the street shaked as though someone was jumping on it. ''The staff ran away scared so the drinks have been free.''
Te Anau helicopter pilot Mark Deaker said he saw power lines arcing and sparks were flying in the air.
Fresh Choice supermarket owner Keith Cullen said 10 to 20 items smashed in each aisle of the supermarket.
Central Southland man Warren MacPherson said a hanging light in his house would have been swaying "a good six inches each way".
He was on the phone when the quake struck and rushed outside.
"By geez, there was a fair bit of movement," he said.
Inspector Olaf Jensen, of Invercargill, said police were swamped with phone calls from concerned residents but there were no reports of any damage.
House alarms had been activated by the jolt, he said. The quake was significant enough to send staff into doorways.
Neither the Manapouri Power Station and Tiwai Point Aluminium Smelter reported any damage.
A Queenstown resident living in a three-storey apartment said the building shook and swayed. ''Holy crap that was significant,'' the resident said.
The Pacific Tsunami Warning Centre in Hawaii issued the warning soon after the quake struck.
A magnitude 7.2 tremor hit Fiordland near Secretary Island off the Fiordland coast on August 22, 2003. It caused significant landslides in parts of the region.
Scientists recorded about 5000 aftershocks over several months in the wake of the 2003 quake.
Aftershocks occur as the earth's crust adjusts to stresses caused by the main shock, and no two aftershock sequences are exactly the same.
- NZPA and Fairfax