OPINION: Stiff, heavy, brittle. The Royal Commission report on the Canterbury earthquakes spells out why unreinforced masonry buildings exacted such a deadly toll on February 22 last year.
Built between 1880 and 1935, the buildings are not designed to withstand violent ground shaking. Of the 185 people killed in Christchurch, 39 were killed as a result of unreinforced masonry buildings collapsing.
Among the victims were motorists, passers-by, bus passengers and occupants of neighbouring buildings. In fact, just four of those killed by the buildings were inside them at the time of their collapse.
The lesson for city planners is that unsafe buildings present at least as great a danger to the general public as they do to their occupants. Nowhere is it more important that that lesson be absorbed than in Wellington, which sits atop multiple faultlines and boasts a large number of buildings pre-dating the use of steel and reinforced concrete.
With their low profiles, parapets and ornamental facades, unreinforced masonry buildings add to the charm of the capital in precincts like Cuba St. However, in an earthquake they increase the risks to those in and around them. Society for Earthquake Engineering guidelines suggest that earthquake-prone buildings - into which category many unreinforced masonry buildings fall - present at least 10 times as great a risk to their occupants as new buildings.
Statistically, earthquakes are not a major cause of death. Since 1843, 483 people have died in earthquakes in this country. In the past three years almost three times as many have been killed on the roads.
However, statistical comparisons are cold comfort to those trying to rebuild their lives in the rubble of Christchurch. So is the cost benefit analysis prepared by the Business, Innovation and Employment Ministry. It assesses the financial benefit of bringing all commercial and apartment buildings up to 34 per cent of the new building standard within 15 years at $37 million. It puts the cost of doing so at $1.717 billion.
The challenge for the Government is determining the acceptable degree of risk.
The royal commission has recommended that all unreinforced masonry buildings be brought up to the minimum standard within seven years and that all other earthquake-prone buildings be strengthened within 15 years. The ministry wants to give all owners, whether of unreinforced masonry or other buildings, 15 years to meet the minimum standard or demolish their buildings.
That is too long. Its analysis puts a value on human life, but it does not count the cost of disrupted lives, interrupted production, lost confidence or rebuilding a broken city.
A degree of realism is called for. No building can ever be 100 per cent safe, but as the post-quake demand for building standard-compliant premises shows, Kiwis do not want to work and live in ''earthquake-prone'' buildings that are likely to collapse in a ''moderate'' earthquake.
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