New Zealand should be more aggressive in making buildings able to withstand earthquakes and can learn from Christchurch's devastating quake, a leading structural engineer says.

President of the Structural Engineers Society John Hare, who is working with an urban search and rescue team at the badly damaged Christchurch Cathedral, said Christchurch may have been "a little passive" in strengthening its buildings.

The same could be said for other centres nationwide, such as Auckland, Mr Hare said.

"I would hate to have an earthquake in Auckland, because I don't think there has been very much done about it at all, I think people have been very complacent," he said.

"I think a lot of engineers perhaps were not listened to."

Because modern earthquake standards only took off in the mid '70s, it was important to retrofit buildings built before to reduce the level of damage in an earthquake.

The aim for designers was to make buildings able to withstand a one in 500 year earthquake event and hopefully a one in 2500 year event.

"What we've had was pretty much equivalent to a one in 2500 year event, or maybe even more," he said.

"I think people may be fooled by the fact it was only a magnitude 6.3 earthquake... magnitude is one measure - you have also got to consider things like depth and proximity."

With the devastation caused by Christchurch's earthquake "fresh in the mind", Mr Hare hoped New Zealand would be more aggressive in strengthening buildings in the future.

"I talked to a builder a few days ago... who said 'when we were doing some of that work you told us to do we used to think you were going over the top, but now I'll never say that again'."

"Preparedness is the answer, the better prepared we are the lower the impact would be," Mr Hare said.

Thomas Heaton, professor of engineering seismology at Caltech in Los Angeles told the LA Times that New Zealand was not the only country which could learn from the quake.

California, which has multiple fault lines running under it, had similar problems when it came to quake strengthening building as New Zealand, Mr Heaton said.

A big concern was the damage to concrete-framed office buildings erected in the '60s and '70s, which California had a lot of, Mr Heaton said.

"People who are living and working in these buildings are largely unaware that they're in buildings that are deemed by most professionals to be dangerous."

The immediate priorities for engineers following the quake was helping with the rescue and recovery operation, determining which buildings were safe and trying to get essential services back online.

Mr Hare said he dreaded to think how long it would take to restore some services.