Christchurch Rebuild: Forget the fear and live with it

Richard Sharpe. Photo / Brian Moorhead

Richard Sharpe is sanguine about the personal risk to life and limb from earthquakes saying the really important issue is to focus on resilience.

"The priority is life first, then the building," he stresses when it comes to earthquake preparedness. He points out that we are living in a country which has this particular natural hazard. People need to "harden up a bit"; not be frightened. But have it in their psyche to "do more than they are at the moment".

At his Wellington offices on Molesworth St, Beca's technical director: earthquake engineering points across to the Wellington fault, which bisects Thorndon. The 2013 Wellington earthquakes on July 21 and August 16 resulted in little damage to city buildings - they were "just at the threshold level for damage of a well-constructed building".

But Sharpe has ensured there are bungee cords holding files in place and all heavy items are screwed to the walls. ("Bungee cords from the local boat shop, attached over files and shelves because of the trauma of stuff falling out.")

He says the public often asks if a building is good enough for a magnitude 7.5 earthquake. "This is a legitimate question - what would happen here (Wellington), well it won't be pretty, as every 500 to 700 years it is thought to go.

"But I would be surprised if there was large loss of life in Wellington."

Sharpe vividly remembers the Inangahua Junction magnitude 7.1 earthquake in 1968 ("I woke up after a capping event and I was wondering what had happened the night before!").

But he points out that life entails other risks - like being hit by lightning or while crossing the road. "You need to have perspective."

In the wake of the Christchurch earthquakes there is pressure to ensure hospitals and schools are built to higher standards.

"That's all to the good. But human behaviour also comes into the equation. In Christchurch, 42 people died from parts of buildings falling on them."

After the July 21 earthquake in Wellington, people ignored the message to stay home and entered the zoned off areas and pushed through the cones and broken glass.

Sharpe suggests a new campaign - "Fix, fasten and Don't forget" - so people harden up.

Among his learnings are:

• People don't understand that if the building doesn't seem to be damaged, then it is probably best to use it. "The risk is after the initial shock, people evacuate but are at risk of an aftershock breaking windows and being hurt by shards of falling glass."

• Floor Wardens should be trained to support people in earthquakes; checking stairs before descending is a sensible move. There should also be earthquake drills.

• Standing under nearby building verandahs (as with fire drills) is not a sensible option.

• It's not the initial earthquake that does all the damage; damage can also occur to buildings in the settlement phase.

Portfolio owners are screening their buildings to determine how earthquake prone they are. Sharpe stresses that even a brand new building could fall down if the earthquake was big enough. "We can design for higher levels with more ductility, effectively reduce the loads and presumably the cost, to accept damage, but not collapse.

"After Christchurch, people are saying that perhaps that's not quite the right model; perhaps society actually wants less damage," he notes. "But you have to pay for it of course. The toolbox includes stronger buildings, adding in bits and pieces that could be replaced if damaged, base isolate and put the whole thing on rubber, lift the whole level of resilience up."

He says a lot of weight will be placed on the new building standards. "But it's not practical after every shake to do full and comprehensive going back to the birth of the building and any sins that might be incorporated ."

He says it's notable that Contact Energy - which faced a dilemma about whether to move out of Wellington's Kirks' building while it was strengthened - decided to stay put through the process. But the owners ot the Majestic Centre spent $54 million strengthening that building to 100 per cent of code.

What is the tolerable impact of earthquakes?

This issue dominated the NZ Society of Earthquake Engineering Annual Conference that took place in Auckland last week. Experts gathered to share learnings from the Christchurch earthquakes and about New Zealand's preparedness to cope with other disasters.

• Resilient Auckland Expo was held to enhance citizens' awareness of what they should be doing to mitigate risk from earthquakes and reduce the impact of disaster on commercial properties, homes and themselves.

Though Auckland has been listed as one of the most liveable cities in the world (by the Economist Intelligence Unit), enhancing resilience and preparedness will help to ensure this position is maintained in times of disaster.

Wellington Council

• Has been very active evaluating risk for many years.

• Conducted a resilience survey in March 2009.

• Implemented standard codes on ductility and the reliance of buildings.

Christchurch City Council

The resilience concept was proven in Christchurch which carried out a full lifelines project well ahead of the earthquakes.

It was designed for life safety at a random level (a one in 500 years return period for a major shake).

Beca's Richard Sharpe says Christchurch was expecting a rolling motion earthquake but it was caught by a "viscous close one''.