The New Zealand township remains unreachable by road, due to massive slips and damage on State Highway 1 after a magnitude 7.5 quake hit just after midnight on Monday morning.

Hundreds of aftershocks had since followed, keeping residents of North Canterbury on edge.

High winds and seas may hamper the military's ability to help people stuck in Kaikoura, Minister of Defence Gerry Brownlee says.

"It wouldn't have been the most comfortable night," Hurunui District Council chief executive Hamish Dobbie said on Tuesday morning.

Civil Defence's acting national controller Shane Bayley said anyone who wanted to get out would be able to do so on helicopter flights throughout Tuesday.

There were four NH90 helicopters in operation "ferrying people in and out as well as supplies", which would be used to fly out those wishing to leave.

Tourists began being airlifted out of the region on Monday night, with a chartered helicopter flying some Chinese nationals out, Bayley told media in a briefing at Civil Defence's national emergency control centre at Parliament.

Tour agency Stray Travel planned to fly a private plane in on Tuesday morning to carry 30 foreign tourists and their driver to Christchurch.

"The weather's always going to be a factor, and potentially it will affect helicopter flights and the use of ships," Bayley said.

However, the weather was forecast to ease later on Tuesday.

Two Navy vessels en route to the area from Auckland would arrive on Wednesday morning with supplies, and would also evacuate people.

The full extent of the damage to the area was still not known.

On Monday night, between 70 and 100 people remained at Takahanga Marae with nowhere to go.

That was a significant drop on the 700 people who had stayed at the marae following the earthquake in the early hours of Monday morning.

The Canterbury Civil Defence Management Group would send building inspectors and council staff into Kaikoura on Tuesday to "support the response and to boost capability on the ground".

"There's a lot of activity planned for today," Bayley said.

Power and communications were still "intermittent" and there was a big effort going on to get the inland roads into Kaikoura up and running but it will take a couple of days.

As for reopening State Highway 1, which was closed between Blenheim and Kaikoura, and Seddon and Chevior, Bayley said, "that's a major project".

In the meantime, those still in Kaikoura were asked to sit tight.

Some supermarkets took precautions as water stocks ran low.

They were urged to conserve water, with just three days' supply remaining.

"The message is to conserve water and be prepared for a long period of time not being supplied properly," Bayley said.

A welfare centre remained open in Waiau, one of the town's hardest hard by Monday quake. Other welfare centres in the district closed after the tsunami warning was lifted.

Leader Rd and Inland Rd, between Waiau and State Highway 1 on the east coast, remained closed on Tuesday.

State Highway 7 (Lewis Pass) reopened on Monday, and one lane of State Highway 7A to Hanmer Springs village reopened on Tuesday morning.

"We understand some people have got through (on Leader Rd) but we understand it's pretty difficult going through there," Dobbie said.

Some local roads were also expected to have been damaged.

"There's a lot of roads that we haven't got to through there, so we don't know what the condition of them is yet."

The council's priority on Tuesday was getting Inland Rd open between Waiau and Kaikoura and restoring power back to water pumps across the district, Dobbie said.

Generators were being used to keep affected pumps going, but residents were urged to conserve water until power was restored and should boil water as a precautionary measure until further notice.

"We're asking people to only use what they need."

Stuff