Up to 100,000 landslides were caused by New Zealand’s 7.8 magnitude earthquake, officials said, as aftershocks continued to shake parts of both islands of New Zealand and emergency crews worked to help people in the main affected areas.

A major relief effort continued on Tuesday, with thousands of people stranded by the quake, which blocked roads and damaged many buildings across parts of the North and South islands.

Emergency services and defence personnel were evacuating hundreds of tourists and residents from Kaikoura, the heavily hit South Island town, amid more strong aftershocks on Tuesday.

The powerful earthquake killed two people. It struck just after midnight on Sunday, destroying farm homesteads, sending glass and masonry toppling from buildings in the capital, Wellington, on the North Island and cutting road and rail links throughout the north-east of the South Island.

As aftershocks continued to rattle the region on Wednesday, emergency services cordoned off streets in Wellington and evacuated several buildings due to fears one of them might collapse.

Gale-force winds and rain were hampering recovery efforts as wild weather brought floods to the Greater Wellington region. Hundreds of aftershocks continued to rock the region. A 5.4 tremor was among the bigger aftershocks and was felt strongly in Wellington.

Kaikoura, a popular base for whale-watching about 150km (90 miles) north-east of Christchurch, the South Island’s main city, was completely cut off by massive landslips.

Four defence force helicopters flew in to the town on Tuesday morning and two navy vessels were heading to the area carrying supplies and to assist with the evacuation, said Air Commander Darryn Webb.

“The priority today is the airlift operation,” he said. “We’re looking to do as many flights as we can out of Kaikoura today ... to move approximately 200 of those tourists and residents south.”

Around 1,200 tourists were stranded in the town, officials said, and other emergency services were using helicopters to fly in supplies and fly out those who wanted to leave.

Mark Solomon, a leader of South Island indigenous Maori Ngai Tahu tribe, which has tourism and fisheries businesses around Kaikoura, said the local marae (Maori meeting place) had received 1,000 people since Monday morning. Many slept overnight in the communal hall or in vehicles outside.

The tribe had fed them with crayfish, a delicacy for which the South Island town is famous. With no power, the tanks that hold the expensive crustaceans had stopped pumping.

“It’s better to use the food than throw it in the rubbish so we sent it up to the marae to feed people,” Solomon said.



China chartered four helicopters to evacuate around 40 nationals from Kaikoura, mostly elderly and children, late on Monday, said Liu Lian, an official at the Chinese Consulate in Christchurch.

People in Kaikoura were being told to urgently conserve the existing supply and use it for drinking only. Food and fuel resources were also low, though local restaurants and residents donated much of their own stores to the relief effort including seafood and crayfish.



The New Zealand Transport Authority was working with contractors to urgently clear an inland route to the town in the coming days, though their efforts were hampered by hundreds of aftershocks since the quake.

Canterbury civil defence response manager Janelle Mackie said: “No doubt it is tough conditions on the ground but the community is pulling together. It is a significant event to respond to but in some ways people feel like they have been there before with the Christchurch earthquake and know how to respond quickly and effectively.”

The New Zealand Red Cross had teams on the ground in Kaikoura operating an evacuation centre and distributing supplies and support to the town’s residents and visitors, said Lauren Hayes, New Zealand’s Red Cross’s media liaison.



The prime minister, John Key, visited quake-affected areas on Monday in a military helicopter and said the destruction was much worse than he had initially realised.



He told Radio New Zealand that the rebuild would require “months of work” and the cost for rehabilitating Kaikoura and the wider north Canterbury region could run into the billions of dollars.



“So the slips here are horrendous … and you’ve got to believe it’s in the billions of dollars to resolve these issues, they’re huge slips … I’m not sure how long it will actually take to move this level of rubble off the road, not to mention the damage to the railways,” he said.



The country was spared the devastation it saw in 2011 when an earthquake struck the city of Christchurch and killed 185 people. That quake was one of New Zealand’s worst disasters, causing an estimated $25bn in damage.



Police said one person died in Kaikoura and another in Mt Lyford, a nearby ski resort. Several other people suffered minor injuries in Kaikoura, police spokeswoman Rachel Purdom said.

Monday’s quake caused damage in Wellington, the capital, and was also strongly felt in Christchurch. Residents said the shaking went on for about three minutes.



Officials said some large buildings in Wellington were showing signs of structural stress. The city’s suburban rail network shut down while crews checked tracks, bridges and tunnels.



New Zealand, with a population of 4.7 million, sits on the “Ring of Fire”, an arc of seismic faults around the Pacific Ocean where earthquakes are common.



The location of Monday’s quake largely helps explain why the damage was less than the 2011 earthquake, said Mark Quigley, associate professor of active tectonics at the University of Melbourne in Australia.

The 2011 quake was located almost directly beneath Christchurch, meaning tens of thousands of people were exposed to the most violent shaking at the epicentre. Monday’s quake was centred in a rural area home to just a few thousand people.

The 2011 quake also had a tremendous amount of high-frequency energy, including very strong vertical ground motions that felt “like you’re being picked up by a giant and being shaken around”, Quigley said.

But for those in Christchurch on Monday the shaking felt very different — more of a rolling motion. “They were far enough away that a lot of that high-frequency energy was dissipated,” Quigley said.

The quake was centred 93km (57 miles) north-east of Christchurch at a depth of 23km (14 miles), according to the US Geological Survey. The USGS initially estimated it had a magnitude of 7.4 before revising it to 7.8.