Brian Rudman: Relax, it's only volcanoes we have to worry about

Photo / Brett Phibbs

The instinct to throw one's hands in the air after the Christchurch earthquakes and demand that any suspect Auckland building be named and shamed is understandable. But what then?

The Auckland Council has done a preliminary study of earthquake-prone buildings and come up with a total of 4300 built before the new national earthquake code of 1976. Many of these are pre-1935 unreinforced masonry buildings, which the city's acting manager of building control, Bob DeLeur, told councillors yesterday were "held together by gravity rather than mortar".

Earlier in the year, consulting engineer David Hopkins estimated retrofitting the pre-1935 buildings alone, to better cope with an earthquake, would cost $66 million.

Reinforced concrete buildings constructed between the 1940s and 1976 are also vulnerable in a big shake. And it doesn't stop there. In Christchurch, more than half the deaths occurred in the Canterbury Television Building, erected in 1986.

The Building Act requires councils to identify earthquake-prone buildings and to have a remediation programme. The old Auckland City Council, in whose territory the majority of these buildings stand, took a very relaxed attitude, setting a deadline of 2045 for upgrading to be completed. The outlying councils, now absorbed into the super city, did not even draw up a list of suspects. Who can blame them?

Unlike shaky Wellington and Christchurch, both with a history of earthquakes, Auckland is mercifully free of this form of natural disaster. We do get little shakes from time to time, but the experts seem to agree a big one is very unlikely.

After Christchurch, the Institute of Geological and Nuclear Sciences, revisited their 2006 judgment that Auckland was an area of low seismic risk and found nothing to change their minds. If we want to have nightmares, it's volcanic eruptions, not earthquakes, that should bring us out in a cold sweat.

As a result of the GNS report, Auckland Council officials recommend going along with the maximum standard outlined in the act. That is that suspect buildings have to be brought up to at least one-third of current building code standard.

For buildings that "contain people in crowds or contents of high value to the community", upgrading has to be completed within 10 years. For scheduled heritage buildings and other buildings, the upgrade deadline is 2035.

The Building Act view that it is acceptable to bring buildings only up to 33 per cent of the new building standard doesn't make much sense. After the Christchurch quake, Canterbury University civil engineering Professor Stefano Pampanin said 34 per cent was "not appropriate. Even going to 50 per cent is not good enough." In other words, even if owners spend a fortune strengthening their old "heritage" shops to the new building code standards, they could still fall apart in a serious earthquake.

To be perfectly safe, you'd have to take a bulldozer to every old unreinforced brick building - to say nothing of some, if not all of those concrete buildings erected before the new code of 1976. The effect on the landscape of older parts of Auckland would be as calamitous as if an earthquake had struck. Except that people and shop contents would be out of harm's way.

In the CBD, there would be gaps up and down Queen St. I haven't seen the list, but one suspects Karangahape Rd and High St would be flattened. Suburban shopping strips like Dominion Rd and Mt Eden would be no more.

In other words, Auckland would end up looking like central Christchurch by trying to protect itself from the damages likely from a Christchurch-sized quake.

By law, councils have to compile a list of vulnerable buildings and have an action - or until now at least, an inaction - plan. If they want to preserve the distinctive Edwardian shopping strips of old Auckland for the public good, the council should also be researching how best to retrofit these old buildings and sharing this information with property owners. Professor Pampanin says it's not necessarily expensive. They should get him to advise them. Then pass on the information to the property owners facing a deadline.

Everyone should also relax a little. If the end of the world is nigh, in Auckland's case, the record suggests it will be heralded by spouting lava and molten rock, not underground tectonic plates rubbing against each other and shaking the city down.