Wellington's port would be unusable if a large earthquake struck within the next three months, senior officials says.

Photo: RNZ / Michael Cropp

CentrePort would be expected to play a key role in the event of a major earthquake, handling thousands of tonnes of fuel and food, as well as vital infrastructure.

But people in senior local and regional government positions, who did not want to be identified, told RNZ that if there was an earthquake as large as November's quake, it was clear the port would fail.

The latest 'lifelines' planning document from Wellington Civil Defence showed that if the faultline under the city ruptured the capital must be prepared to be cut off for months.

The document assumed that roads would fail, and the airport would be unusable except for military aircraft.

But within four or five days, CentrePort would be expected to be able to receive its first ship, the document said.

And for the following four months it would need to handle about 90 percent of the food and fuel needed for the 400,000 people in Wellington, Porirua, and the Hutt Valley.

'Resilience is absolutely key' - CentrePort

Photo: RNZ / Michael Cropp

The port's chief executive, Derek Nind, would not confirm the extent CentrePort was damaged in November 7.8-magnitude Kaikoura quake but acknowledged it was significant.

"What we've done is we've mobilised all our resources to keep the port operating at the best level we can. We're focusing our resources now, as we transition out of that triage area, into temporary works and beyond and building resilience into that thinking," he said.

A tour around the port this week made clear the port had been hard hit.

The container wharf was closed, the reclaimed land it was built next to has sunk by nearly a metre and a 200m-long section of road has disappeared into the harbour.

A patchwork of new asphalt showed where urgent levelling work had taken place.

On the slumped, reclaimed land behind two 750-tonne cranes, contractors were strengthening the soil with 500 stone columns and 180 steel and concrete piles.

CentrePort's chair Lachie Johnstone said that work, which was due to wrap up in July, should help the port stay operational through future earthquakes.

"As we have the opportunity to repair and re-look at all the infrastructure at the port, resilience is absolutely key," he said.

"We are a critical infrastructure asset and our ability to get back in and get back operating after a significant event is absolutely critical."

Council investigating other options - mayor

Wellington Mayor Justin Lester said losing the port was a real possibility, but there were contingency plans, such as bringing in pontoons - a type of floating wharf - and for the Navy to use marine craft that could land on the shore.

Photo: RNZ

But that would be less effective than having working wharves at the port.

And Mr Lester said the city needed to be prepared if the wharves failed.

"That's a very real possibility that you could have the lifelines closed and you could have damage at the port. That's why we're looking at options like the floating pontoon. That's why we're looking at options to increase the ferries' resilience, we're looking at a terminal project together with the Interislander and Bluebridge, with CentrePort leading the way on that," he said.

Mr Lester said the region was seeking a partnership with the government to make its lifelines more resilient.

The city was also seeking assurances that the plans in the lifeline documents could be executed - with, or without the port.