Lyttelton Port will take at least 24 hours to assesses significant damage to wharves and other infrastructure after today's earthquake.
Port chief executive Peter Davie said cranes and machinery were undamaged in the magnitude 6.3 quake this afternoon. However, it was too early to say how extensive the damage was.
"We're at the stage of knowing we've got significant damage, and waiting until first light to work our way through and work out how significant.
"Parts of it are quite badly broken up and other parts aren't so bad," he told NZPA.
"It's wharves and paving that's smashed up - there are places where walls have dropped half a metre."
The port company had told customers it would take 24 hours for engineers to assess the damage.
"There's still ships doing things in the port, it's just a matter of what cargo we can and can't load."
Most staff had been sent home to be with family.
Davie was in central Christchurch when the quake happened "and it wasn't good".
"A lot of things and a lot of people smashed up badly," he said.
"I actually went home first because I've got three kids, I had to look after them first, then I shot over the hill (to Lyttelton), and that was fine."
The port company had not determined the final cost of damage from the 7.1 magnitude earthquake in September, with estimates reported between $50m to $200m.
Despite being extensively damaged in that quake, it was operational again within hours.