Re-examining our building codes

Based on seismic data and historical records, New Zealand experiences about 300 - on average - 4 to 4.9 magnitude earthquakes every year, and an average of two magnitude 6 to 6.9 a year. As we have so tragically discovered, earthquakes of these magnitudes can kill and will damage and destroy many man-made structures.

The Minister for Earthquake Recovery, Gerry Brownlee, was quite right to state this week that no more people should die trying to save Christchurch's unreinforced, non-earthquake-proofed historic buildings: the safety of human life must come before the preservation of buildings, however "iconic".

Since no part of New Zealand is safe from earthquakes, it is certain the lessons of Christchurch will mean the reconsideration of building codes, including codes for relatively modern and supposedly safer structures.

What this will mean for the rest of New Zealand is moot, although it is relevant to remind ourselves that Wellington underwent a substantial, costly and controversial process 30 years ago which saw many historic buildings demolished because they did not meet new building codes, and many new buildings erected which are supposedly far safer for human occupation, especially when fitted with vibration control technologies such as the lead-rubber base isolation system invented here by Dr Bill Robinson.

Many of our buildings and bridges are now fitted with this system, including Parliament and the Museum of New Zealand, but notable historic buildings, especially of the 19th century, have no such protection. This state of affairs is especially relevant to Dunedin which, although more distant from major known fault lines, cannot be considered any less vulnerable.

The scale of potential damage and destruction in Dunedin's central business district should an earthquake of Christchurch's magnitude strike may be assumed to be colossal. Mr Brownlee has declared, somewhat imperiously, that historic buildings in Christchurch if they have "any damage at all" will be demolished, no matter what their connection to the past.

He was annoyed that the Christchurch City Council refused consent to allow historic structures damaged in the September event to be demolished, and has declared the council will not have that power "this time", noting that several workers while engaged in the renovation of some of those buildings were killed in last week's earthquake.