The 7.5 magnitude earthquake in the upper South Island that killed two people and triggered tsunami warnings disrupted the port operations of at least four cities.

Port operations in Napier, Wellington and Christchurch were all hit by the quake, centred near Hamner Springs in the Hurunui district, which has also cut power across parts of the lower North Island and upper South Island, disrupted rail and ferry services across the country and shut down the capital's CBD. The Ministry of Civil Defence and Emergency Management says there is still a tsunami marine and beach threat from Napier to north of Dunedin, Cook Straight coastal areas and the Chatham Islands, but has lifted its warning for other regions.

Christchurch's Lyttelton Port Co, which embarked on a long-term redevelopment plan after the 2011 earthquakes, has re-opened some operations, receiving and delivering freight and cargo including logs and cars, and hasn't found any major concerns in its inspections so far, it said in a statement on its website.

"The railway line south of Christchurch is open, as is the Rolleston to Christchurch route. However, the Christchurch to Port route remains closed and we are awaiting further updates from KiwiRail," it said.


Napier Port closed while the tsunami warning was in place, and the sole boat in port, a fishing vessel, was sent out to the harbour, a spokeswoman said in an emailed statement.

"Operations resumed early this morning and we are monitoring the wave activity closely," she said. "Our engineers are undertaking a full assessment of our infrastructure, including hydrographic surveys of the inner port and shipping channel, and early indications are that the port has not sustained any damage."

State-owned rail operator KiwiRail, which runs the inter-island ferry service, says Wellington's ports have sustained damage, though council-owned operator CentrePort, which was damaged during the 2013 quakes centred in the upper South Island, has yet to comment, and Timaru's PrimePort evacuated staff in the early hours of the morning, according to a Timaru Herald report.

Dunedin's Port of Otago said it hasn't faced any disruptions from the quake or tsunami warning, while Bluff-based South Port New Zealand wasn't immediately available for comment.

Some courier deliveries are continuing today although road damage will impact freight over the coming days.

Dean Bracewell, managing director at courier company Freightways, said the company is still learning about what the impact of this morning's earthquakes means for its business, and most importantly all its employees are safe.

Freightways' information management facilities are fine with no obvious damage, Bracewell said, and courier deliveries are happening "largely as per normal" today.

Inter-Islander freight has been delayed as the ferry services have been suspended, while Freightways' Christchurch air freight is continuing as per normal with the airport open.

"We have a range of contingencies to put in place for Christchurch, Nelson, Blenheim and the top of the South Island where road access had been most impacted, and we are in the hands of the authorities about that access," Bracewell said.

Transport and logistics group Mainfreight said rail services in the lower North Island and South Island have been suspended pending track inspections, while Inter-Island rail services have been cancelled until further notice.

"Where practical we will endeavour to provide limited delivery services for freight already in our Wellington and Christchurch depots," the company said in a statement on its website. "To avoid unnecessary congestion at this time whilst connections into these regions have been severely impacted we advise early that we will suspend collecting general freight destined for these two regions and outlaying districts until further notice.

"Our teams will look to prioritise the movement of critical supplies such as food as options emerge. Our operational teams are currently surveying all possible options to navigate network blockages as information comes available."

State-owned rail operator KiwiRail, which runs the inter-island ferry service, has said Wellington's ports have sustained damage. Council-owned operator CentrePort, which was damaged during the 2013 quakes centred in the upper South Island, has yet to comment.