A long and powerful earthquake jolted the lower and central North Island and was felt as far away as Christchurch late last night.
Geonet has upgraded the Taranaki quake, which struck at 11.49pm on Wednesday, to a 5.8 magnitude quake after initially classifying it as a 5.0.
It said its epicentre was 25km east of Stratford. Its estimated depth was 187 km.
The quake was rated as "severe" on Geonet's 'felt reports' feature by several people in Hawke's Bay, Manawatu, Whanganui, Wairarapa and Wellington, as well as near its Taranaki epicentre. Geonet classified the shaking from the quake as "light".
Within 10 minutes more than 33,000 people around NZ had reported feeling it. That had risen to more than 38,000 by 12.20am on Thursday.
Some people on social media described it as two separate quakes, while others described it as a very long shake.
Lynne Keys said the quake was "very very scary ... my ceilings all creaked".
Then the whole house "actually wobbled".
"Scariest one I've ever felt! Not sure if it was good or bad getting the warning in my phone first."
Commenters on Geonet's Facebook page variously described the quake as a "jolt", "long light shaking", and a "long wobbly one".
Many were woken by the shaking but others heard it before they felt it, with one thinking it was a truck.
"I heard it for about 5 seconds before the shaking started, so I knew it was going to be relatively big. The house lurched about quite a bit," another person said.
Across the country, Kiwis reported that they had received an Android Earthquake Alerts System notification on their phone a few seconds before shaking started.
Google has chosen New Zealand and Greece to trial its new system, which uses mobile phones to detect seismic waves, then centralises and assesses the information and warns users according to their location.
It's the second earthquake to strike Stratford in the past two days. A 3.8 magnitude quake hit 40km from the town about 9pm on Tuesday.
In Whanganui, the quake was "like a huge truck in the neighbourhood" and woke Jacob McSweeny just from the sound alone.
"Then the house shook for a good 20 to 30 seconds. Nothing broke or fell - just a good shake up."
Katrina Derham in Hawke's Bay wrote that it was "crazy that it was centred in Stratford but felt so strongly here. Was a real jolt."
Some Twitter users in the capital city were reporting that it was powerful enough that things fell over in their home.
Kat Zolita Mason in Wellington wrote that it was such a long shake that it "felt there were two".
"I went into the hall and watched the paintings shake."