John Roughan: Regulating on shaky ground

Auckland has plenty of time to prepare for earthquakes and higher tides. Photo / NZ Herald

New rules would destroy built heritage, cost billions, save few

The harbour was looking lovely on Thursday morning. The tide appeared higher than usual, as though the expected 3am swell from the Chilean earthquake was still lifting the sea level. The mangroves were covered and the water was slopping pleasantly closer to the Northern Motorway on the approach to the bridge.

Would this be Auckland a century hence? This week's umpteenth report from the Intergovernmental Panel on Climate Change repeats the warning that sea level in New Zealand will rise all of half a metre in 100 years. Half a metre. Climate Change Minister Tim Groser said it confirmed the Kiwi dream of a bach right at the water's edge was no longer a good idea. That's about the size of it.

A century is simply too long for human nature to worry, or at least it is too long if the predicted disaster is a slow burn. It is plenty long enough for people to move if necessary, for crops to change, fresh water to be managed much more efficiently. Human life will adapt if it has to, it doesn't need to return to some pre-industrial age of bicycles and village crafts.

We should take the same attitude to earthquakes. Despite the fact that two New Zealand cities have been devastated by them within the past century, the risk of a quake of destructive magnitude in any given location must be very much lower than the risks of climate change.

A century is negligible in geological time. Many thousands of years pass between movements on a particular fault. Yet while the authorities are sensibly relaxed about the risk of a climatic catastrophe, they are about to require older buildings to meet an earthquake code that could knock over most of our built heritage within 20 years.

Ian Harrison is a Wellington public policy analyst who has worked for the Reserve Bank, the World Bank and other international bodies. He is now an independent consultant specialising in the economics of protection against events of low probability but high impact.

This week he produced a paper on recent and proposed changes to New Zealand's regulation of earthquake-prone buildings. He called the paper, "error prone bureaucracy". It made news with its calculation that the bill now going through Parliament will impose costs totalling $10 billion on the country and save possibly seven lives over the next 75 years.

In Auckland, he calculated, the cost would be $3 billion and it would take 4000 years to save a single life. Auckland is further than the other cities from a plate boundary. Research presented to the Auckland Council by GNS Science this week estimated the city could expect a major earthquake every 10,000 to 20,000 years.

Earthquakes are not only extremely unlikely in the lifetime of a building, when they happen they are not very deadly.

When the dust had settled in Christchurch on February 22, 2011, virtually all of the old timber or stone buildings of the inner city had buckled and slumped and many had partially collapsed. Yet the number of people found dead in those "earthquake-prone" buildings was precisely four.

Four people, out of the thousands who must have been inside those shops and cafes at that time, lunch hour, when the city was hit by ground forces greater than the strongest buildings are designed to survive. Clearly timber and stone stands up long enough for people to get out.

The vast majority, 133, of those who died in Christchurch that day were killed in two modern buildings with construction faults. Of the rest, 35 were killed outside on the footpath or the street by falling walls or debris.

Harrison's paper reveals that the building code's definition of "earthquake prone" was changed in 2003, apparently as an afterthought when the code was being revised following the Herald's leaky homes revelations. It is in the nature of bureaucracy that when a specific problem arises, the regulatory itch returns on all fronts.

Harrison's research could find no supporting analysis for the decision in 2003 to increase the standard required of older buildings from 16 per cent of the code for new buildings to 34 per cent. The figure, he says, was "plucked out of the air" on the verbal recommendation of the Society of Earthquake Engineers.

It is never popular to question the value of anything that may save a life. What's $10 billion of building costs if it saves seven lives in 75 years, or one Aucklander in 4000 years? Safety is never absolute. The strongest buildings are prone to a big enough shake.

Major earthquakes are terrifying but the threat to life in old buildings is probably no greater than the dire consequences predicted from climate change. Both could be given that reliable Kiwi risk-assessment: She'll be right.