A major quake has shaken the North Island's East Cape, but has been felt right across the country.
The 7.1 tremor struck at 4:37am on Friday, centred 130km off Te Araroa. It was 55km deep, according to quake monitoring service GeoNet.
There are no reports of damage or injuries yet.
Civil Defence is warning people to stay away from beaches, saying there's a potential tsunami threat.
"The important thing is people stay away from the water," director Sarah Stuart-Black told Paul Henry.
"They should be going inland or up hills if they're close to that coastline. We understand there have been a number of self-evacuations… we're just urging extreme caution."
The first tsunami wave, measuring 30cm high, arrived on the East Cape at about 6am.
"It is considered a threat because it's different from the normal sea currents and movement," says Ms Stuart-Black.
"This lasted longer than any other one that I've ever felt," one caller told RadioLIVE. "I hate them. I just hate them."
"I felt it, and I'm in Manurewa," said another.
Dan Hood, in nearby Kanakanaia, was woken up by the severe tremors.
"The thing with an earthquake is you never know where they're gonna go," he told RadioLIVE.
"The scary part was wondering if there was a big jolt coming, or whether it was just going to subside and disappear. But I'd imagine we'll get a few aftershocks after something like that."
Gisborne Mayor Meng Foon says he was woken by the quake, but understands people in his region are okay.
"I don't have any reports of any damage, but I do have reports that people are okay. People have indicated yep, there's nothing untowards in their own homes, so that's good."
It could also be felt in Auckland, Northland, Palmerston North, Napier and even Blenheim and Christchurch in the South Island.
"I was sitting at my laptop here in Christchurch and felt the quake," Christchurch resident Gary Neame told Newshub. "The plant beside me was swaying for a good 20-30 seconds."
"Was a good wake up in Gisborne," Zoe Toms wrote on the Newshub Facebook page. "Didn't think it was guna stop. Could see the house moving. Have felt 3 good aftershocks [sic]."
There have been several aftershocks, measuring as strong as 6.2.
Civil Defence says aftershocks should be expected. It has put out a list of recommendations for those close to the epicentre.
Expect aftershocks and remember to drop, cover and hold.
Look after yourself and get first aid if necessary. Help others if you can.
Assess your home or workplace for damage. If the building appears unsafe get everyone out. Use the stairs, not an elevator and when outside, watch out for fallen power lines or broken gas lines. Stay out of damaged areas.
Look for and extinguish small fires if it is safe to do so. Fire is a significant hazard following earthquakes.
Listen to the radio for updated emergency information and instructions.
Do not overload phone lines with non-emergency calls.
Help people who require special assistance – infants, elderly people, those without transportation, families who may need additional help, people with disabilities and the people who care for them.
Friday's quake follows a 5.7 tremor that shook the same area yesterday.