Even buildings that have been deemed safe after an earthquake can have internal damage, Quake Protected says.

Primary focus for this morning's earthquake was examining the structural soundness of buildings and cleaning up the obvious external damage.

But Jeremy Baker from Quake Protected said to expect growing reports of internal damage to office buildings and retail outlets.

"A lot of damage can happen even in buildings that are structurally sound," said Baker.

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"Suspended ceilings, air conditioning, lighting and sprinkler systems can suffer significant damage especially in offices, supermarkets and retail outlets."

An example was the near-new BNZ Harbour Quays complex in Wellington which came through structurally unscathed after the city's 6.5 magnitude earthquake in July 2013.

But it suffered extensive internal damage due to collapsed suspended ceilings and burst water pipes and sprinklers.

The building was closed for six months before the first staff could return.

BNZ estimated that the cost of fixing the building and relocating staff ran to about $10 million.

"Externally the building looked fine, but internally it was a disaster," said Baker.
"The problem comes from people only focusing on structural strength."