Two people have been confirmed dead after a powerful 7.5 earthquake hit North Canterbury at 12:03am on Monday.
There are also reports a person has been trapped in a landslide in Ohau, north of Kaikoura. The Kaikoura District Council has declared a local state of emergency.
The earthquake has triggered more than 100 aftershocks, which have been felt as far north as Auckland and continue to shake affected areas.
One of the deaths was reported at the Elms Homestead in Kaikoura and one in Mt Lyford, east of Hanmer Springs.
A 100-year-old woman was rescued from the Homestead, while her son is believed to be one of the deceased.
Damage on State Highway One (Henry McMullan/Twitter)
GeoNet says the initial 7.5 magnitude quake may have actually been two quakes, based on aftershocks being felt in separate locations.
The Clarence River community has been evacuated after the river breached a slip dam and sent a large wall of water heading downstream. Residents were advised to move to higher ground immediately, and police have contacted landowners to advise them of the risk.
The Marlborough District Council says a group of 16 rafters on the flooded river have been found safe. There are around eight to 10 houses around the river mouth and a few up up the river.
Tsunami waves were recorded in Kaikoura, Wellington, Christchurch and Castlepoint in the Wairarapa. Tsunami warnings have been lifted for the entire East Coast of New Zealand, but Civil Defence says a marine and breach threat warning remains in effect until a cancellation message is issued.
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.
An urban search and rescue team of 20 people and two dogs has arrived in Kaikoura to assist.
Four Nelson police officers have been flown in to assist, with more to arrive tomorrow if needed. 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.
Hurunui District mayor Winton Dalley had declared a state of emergency in the area.
"The reason for the state of emergency is to allow us to coordinate the resources we need to get on with the recovery from this earthquake," Hurunui District Council CEO Hamish Dobbie told Newshub from Amberley.
"There's been helicopters flying up and down the state highway to and from Kaikoura," he said.
"They've stopped and picked up a number of motorists trapped between various landslides and road interruptions. They're being flown to Amberley, we'll take care of them once they get here, sort them out and try and get them onwards to where they need to get to.”
"We have physically got to a lot of our small towns now, we've got good connections there. We've just got a helicopter just gone up to Lyford taking another satellite phone in to them so we'll have a better connection with them. But it is difficult."
Slips, cracks and damaged bridges have been reported along State Highway 1, which is closed north of from Seddon to Cheviot. Kaikoura remains essentially cut off by slips and blocked rail tunnels.
Slip on Rotherham Road near Waiau (Newshub.)
A railway line pushed into the sea on State Highway One (Newshub.)
Earthquake damage has also closed State Highway 7, Waipara to Springs Junction, and SH7A to Hanmer Springs.
Trains and ferries are on hold in the Wellington region, with the Interislander reporting two of its ferries, the Kaitaki and Aratere, anchored in the Wellington harbour.
KiwiRail says all lines north, east and west of Palmerston North, as well as the Midland Line between Rolleston and Greymouth are now open.
Kiwirail says the Kaiarahi ferry has berthed in Picton and unloaded passengers after port authorities cleared one berth for use, though the terminal sustained damage and remains closed. Ferry services for vehicle passengers and freight will resume on Monday night from 6pm. Foot passengers will not be able to sail due to damage to the Picton terminal.
Damage on State Highway One (Newshub.)
Reports of damaged buildings have come from a number of regions including Canterbury, Wellington and Blenheim. Assessments of the Christchurch CBD are still being carried out, but damage appears to be minimal.
Wellington City Council has advised those who work in the central city to stay home today as the capital braces for 140km/h winds, which the council says could dislodge broken glass and other materials from buildings that sustained structural damage.
Wellington Regional Civil Defence Controller Bruce Pepperell says a number of major buildings are showing "signs of structural stress" and that the quake will likely have caused mess and disruption inside some buildings, particularly on higher floors.
Damage at the Wellington port (Newshub.)
Wellington Mayor Justin Lester says the city is quiet today. The CBD is open, except for limited areas around Featherston St, and will largely be open for business on Tuesday.
"I am very happy with the work of the Council officials in getting the city on its feet it was a fair shake and we want to make sure everyone is safe when they come back to work," he says.
The New Zealand Parliament building provided refuge overnight to about 300 people who were evacuated from unsafe accommodation nearby.
Among those who stayed at the Beehive are Simon Clegg and his family, who have just moved back from Australia for seven years to live in Wanaka. They were spending the night in Wellington before planning to catch the ferry today, but will instead be looking for a motel to stay in out of the CBD.
"We all ended up in the one room... You were definitely thinking in your head, this is getting out of control."
He says they'd been offered to stay on in the 9th floor room but weren't comfortable because of extensive cracks in the walls that opened up before their eyes.
The family ran down the nine floors, past "massive cracks" in the walls.
Water supplies have been affected as far north as Raglan. The New Zealand Red Cross says water has been identified as an urgent need, and that they will offer water bladders and tap stands for distribution as needed.
Raglan residents are being advised to boil their water for the next three days, as the spring which supplies the town became discoloured following the quakes.
Christchurch City Council is reporting no issues with drinking water.
NZQA has postponed all scholarship exams for the day. NCEA exams will go ahead at unaffected schools. Students whose schools are closed will be given a derived mark based on previous results in the subject.
In Wellington, 104 of the 195 schools were closed on Monday. In Nelson and Marlborough, 91 of the 132 schools were closed, and in Canterbury, 81 of the 197 schools were closed.
The Red Cross has launched an emergency appeal to support communities affected by the quakes. People con donated via the organisation's website.