Officials will investigate how Wellington's multi-storey buildings stood up to Monday's earthquake, focusing on Statistics House.
Photo: RNZ / Phil Pennington
The 7.8 magnitude earthquake caused damage to several buildings in the capital, including Statistics House, 61 Molesworth Street and Defence House.
Another 10 buildings around Courtenay Place and Tory Street were evacuated today, due to concerns about damage to the empty car park building next to Reading Cinema.
"This investigation will focus on Statistics House to understand its performance and where there may be wider lessons for improved design," Building and Housing Minister Nick Smith said.
"My advice from officials is that the vast bulk of Wellington buildings have performed well but if information comes to hand on other issues related to seismic performance, the investigation may be widened."
The building's owner, CentrePort, said it would work closely with officials from the Ministry of Business Innovation and Employment (MBIE) as part of the investigation.
The port company's chair, Lachie Johnstone, said he welcomed the inquiry.
"We're taking an open and transparent and collaborative approach to the inquiry working alongside MBIE, Statistics New Zealand and Wellington City Council."
He said engineers had conducted a preliminary inspection of the building, which was built in 2005.
"Structural engineers have conducted a preliminary inspection of the damaged 'T' shaped floor slabs in the north-west corner of the first and second floors."
Speaking at a news conference, Mr Johnstone said speculation that parts of the building had pancaked were incorrect.
"There has been a situation where the floor sections of the building have separated away from the beams of the building.
"This has happened in isolated areas of the building and I really need to reiterate how fortunate we were that this occurred overnight."
Mr Smith said he'd requested the review of Statistics House in part because it was relatively newly designed.
Assessments were still being done on Defence House, another relatively new building, he said.
"It is actually quite to be able to differentiate between what an engineer would describe as superficial damage and structural damage.
"So for instance while you may have spalling of concrete on the edge of a building, that does not necessarily mean that is it not structurally sound, and the reports on the defence building are not, at this stage, of the point where I would want to include them in the review."
He said it was important people did not jump to "incorrect conclusions" about buildings' seismic performance after Monday's earthquake.
"The frequency of that quake particularly impacted on medium-height buildings but another earthquake or aftershock could more severely impact on low-rise buildings."
The fact most quake-prone buildings did not suffer more extensive damage was more about the type of earthquake, than the buildings' seismic strength, Mr Smith said.
"There is no place for complacency and building owners need expert engineering advice on managing these risks."
If the investigation produced any evidence building regulations should be changed, that would be taken up by the government, he said.
Archives New Zealand, BNZ and New Zealand Post
Archives New Zealand's building in the central city was also evacuated today.
The Department of Internal Affairs said all workers were evacuated from the building at 10 Mulgrave Street as a precaution, after they received a visual report from a structural engineer.
A thorough assessment of the building would be carried out and workers would be kept updated, the department said.
Yesterday, it said the building was declared "seismically sound" and was open for staff only.
A BNZ spokesperson said its building, on Harbour Quay, would not reopen for months
The company initially thought it would take weeks to fix the damage, but today staff were told they would not be back in their offices for months, they said.
The bank was finding other places for its staff to work from.
New Zealand Post's building also suffered some damage but was found to be structurally safe.
Up to 1000 people work in the office on Waterloo Quay, which has been closed since Monday's quake.
A spokesperson said engineers have assessed the building and found it was structurally safe, but there was some damage to some of the floors.
They said it was hoped staff would be able to return on Monday.