A powerful 7.5-magnitude earthquake in Canterbury has rocked a number of regions overnight, with tsunami waves reaching New Zealand's east coast and aftershocks causing havoc nationwide.
Two people are confirmed dead, and quakes have been recorded as far north as Pukekohe, just south of Auckland, meaning a large portion of the country has been affected by the tremors.
There are reports a person has been trapped in a landslide in Ohau, north of Kaikoura.
A tsunami warning was in place for much of the country overnight but was downgraded to a marine and beach threat shortly after 8am. The threat is in place from Napier and Hastings to the Waitaki Coast.
Schools and early childcare centres from Wellington to North Canterbury have been advised to close until structural engineers have carried out building checks.
For schools that remain open, the New Zealand Qualifications Authority (NZQA) says all Scholarship exams have been postponed for the day, as well as for students whose schools were affected by the earthquake. If their school is closed, they will be given a derived mark based on other results in the subject.
All of the country's major airports remain open. All trains in the South Island and most south of Palmerston North are cancelled until further notice.
Below is a rundown of the worst-affected areas.
One person has been confirmed dead. They were killed when the Elm Homestead collapsed in Kaikoura. Another person was injured in the collapse.
Kaikoura is reporting serious damage to town infrastructure, with no sewerage and water and power gradually being restored.
Residents are strongly advised to conserve water as it may be days before household water supply is returned.
Four Nelson police officers have been flown in to assist. Shops are closed, and the public cannot currently buy food, water or fuel.
Travellers are known to be stranded to the immediate north and south of Kaikoura. Police are working to airlift occupants of caravans to the north to the Ward Welfare Centre, while those in south will be airlifted further south.
A massive slip caused by the tremors has left Inland Kaikoura Rd totally obstructed, and large cracks have appeared in a number of roads in the neighbouring coastal town of Cheviot.
The Marlborough District Council has set up a hotline for visitors in the region who are stranded and need help getting out - 0800 777 181.
The capital was hit by small tsunami waves and a warning remained in place overnight. It has since been downgraded to a marine and beach threat.
An Interislander ferry that crossed Cook Strait was stranded in Wellington Harbour after the drawbridge that gets passengers onto the mainland partially collapsed and fell into the water. All Interislander ferry sailings have been cancelled until an assessment of the Wellington and Picton terminals are completed.
The Kaiarahi is currently standing off Picton, while the Kaitaki and Aratere are anchored in Wellington Harbour.
Bluebridge has also suspended sailings until further notice, the company saying it is contacting all affected customers.
The Fire Service says TSB Arena and the BNZ Centre on the waterfront have sustained the most damage.
People in Lyall Bay were urged to evacuate after surging was detected in the water, sending people running for the hills.
Those planning on travelling to Wellington CBD this morning have been advised to stay out until the afternoon.
A large crack has opened up at Wellington's port.
All daytime road works in the region have been put on hold for the day, though scheduled work for the evening will go on, NZTA says.
Around 300 people have been sheltering in the public areas of the Beehive after being evacuated from unsafe accommodation nearby.
Residents of nearby Pahiatua have been urged to conserve water and the council has put in a total hosing ban until the bore has been checked. The bore will be out of commission and in the meantime, the town's water will come from a back-up river supply which has been chlorinated.
The small north Canterbury town is feared to be one of the worst-hit spots in the country, with another person killed in nearby Mt Lyford.
An earthquake saw a slip on the Waiau Ferry Bridge, leaving it badly damaged. There are reports the bridge has sunk as much as 40cm under the weight of the slip.
One man was left unable to reach his father when he discovered the landslide.
The epicentre of the quake, Hanmer Springs, is just a few kilometres away from Waiau.
The Marlborough township has been hit by dozens of aftershocks this morning, which have matched Kaikoura in severity - with some stronger than magnitude-5.
More aftershocks are likely to be felt in Seddon.
Tsunami sirens were ringing out throughout the southern city for much of the night.
People close to the coast were urged to evacuate and head to higher ground, which is advice that appears to have been taken onboard.
Those evacuated following Monday's earthquake can now go home, Christchurch Civil Defence says, with the risk to land downgraded. However, there is still a threat in the marine and beach environment.
"After a difficult night, people will be relieved to be able to get home. However, we are asking for people to be patient. There will be thousands of people looking to go home just as a lot of others will be going to work for the day," Civil Defence controller John Mackie says.
"It's important people are patient and make allowances for other people while travelling."
Evacuation centres are still open, likely until midday.
Checks on stopbanks along the Avon River have shown no visible signs of damage from the quake.
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