The now-named Kaikoura Earthquake triggered 100,000 landslides in Northern Canterbury and southern Canterbury.
The largest of them, brought down on the south side of the Clarence River mouth in the wake of the overnight 7.5 quake, brought down an estimated one million cubic metres.
Thousands of people remained trapped in Kaikoura last night without water, sewerage systems and phone reception after a massive quake struck the South Island.
The 7.5-magnitude quake, which hit near Hanmer Springs at 12:02am yesterday, caused massive landslides blocking access to the district by road and rail.
Two people died as a result of the quake, which also triggered tsunami warnings, sending terrified residents fleeing to higher ground.
One man died and two women were pulled from the rubble in Kaikoura when the historic Elms Homestead collapsed, and a Mt Lyford woman reportedly died from a medical event while she was evacuating her home.
Last night, significant mobile, landline and broadband connectivity issues continued to affect residents in the area, due to damaged infrastructure and power outages.
About 4.20pm a wall of water rushed down the Clarence River, after debris from the quake created a dam which caused a lake to form, then breach.
Residents nearby were evacuated to higher ground, as the water dissipated, and kayakers and rafters feared missing were later found safe and well.
Hundreds of aftershocks continued to rock the country into last night - including a severe 5.8 tremor 25km east of Kaikoura at 7.43pm - with extensive damage also visible in Wellington and Christchurch.
According to Geonet, multiple faults ruptured to cause the earlier 7.5 quake, including one newly identified at Waipapa Bay, north of Kaikoura. Scientists estimate the event, which has been named the Kaikoura Earthquake, triggered 100,000 landslides across Canterbury.
Prime Minister John Key described scenes of "utter devastation" as he flew over the Kaikoura region.
He said long term recovery of the region would cost billions of dollars.
"It is a very, very big job for both the Transport Agency and Kiwi Rail," said Key.
State Highway 1 was "utterly buried."
"You've just got to hope there is no car underneath that."
By 5pm, 630 insurance claims had been lodged online to EQC but a clearer picture of damage was expected to emerge today.
Overnight, winds of up to 140km/h were expected to hurtle across Cook Strait and into Wellington.
MetService meteorologist Tom Adams said winds would be potentially treacherous, especially in Wellington given the number of unsecured structures and broken glass around the capital, which forced bus routes to be redirected yesterday as shards fell from damaged buildings.
Kaikoura would be spared the worst of the wind and rain.
The Defence Force was tasked with delivering essential items to those trapped in Kaikoura, with NH90 helicopters making runs yesterday, and HMNZS Canterbury heading to the area.
The fire service Urban Search and Rescue (USAR) team with two dogs was deployed to Kaikoura yesterday. Between 12.03am and 5am, fire crews were called out 245 times and over the same period calls to St John Canterbury and Tasman regions almost doubled.
Since the earthquake hit, police have received 19 reports of burglaries at Canterbury properties, with one family's Christchurch home looted after they fled to safety during the quake.
More than $20,000 had been raised for them on a givealittle page by last night.
"This sort of offending really scrapes the bottom of the barrel," Canterbury district commander Superintendent John Price said.
Extra officers have been sent from Auckland and Blenheim to Kaikoura to provide support.
A devastating 7.5 earthquake hit the Kaikoura region overnight causing widespread damage. Photo / Mike Scott
Significant damage to the train line between Picton and Christchurch, particularly around Kaikoura, is likely to see closures in the area last several days, KiwiRail said.
Passengers stranded on the Kaiarahi ferry overnight due to earthquake damage at ports in Picton and Wellington were able to disembark by midday yesterday.
And cancelled Wellington train passenger services are expected to resume today.
University of Canterbury Professor of Clinical Psychology Julia Rucklidge said yesterday's quakes could trigger emotional trauma for Cantabrians, though there had been little physical damage in Christchurch.
She said those who had been severely impacted by the 2010 and 2011 quakes would be the ones most affected.
"People who have coped really, really well, can suddenly have an adverse effect based on an earthquake experience," Rucklidge said.
