Canterbury’s finest hour

Even after 40 years in seismic engineering, it feels very strange to stand in the normally bustling centre of your home town and see cordoned-off streets in every direction, deserted because of a major earthquake.

Fresh off the plane from Wellington, where Beca’s earthquake engineering team is based, I stood in the eerie emptiness of Cathedral Square on the day following the 4 September earthquake and saw not a soul, bar a few knots of people in the distance wearing high-vis jackets and craning their heads upwards. I felt a mixture of sadness at the damage to so many local homes and heritage buildings, and pride at the city’s exemplary response to such a major natural disaster.

Christchurch’s performance in the earthquake was tremendous in my opinion. The city council knew exactly what to do on the first day, and proceeded with a textbook implementation of pre-agreed evaluation systems. I am proud that professionals around the world will hold up Christchurch as the gold standard in building design and emergency response in the next few years.

World leader

Internationally, New Zealand is seen as a leader in earthquake engineering, particularly in reinforced concrete buildings, partly because of work done at the University of Canterbury in the 1970s and 1980s.

The Inangahua earthquake near Westport in 1968 galvanised interest in seismic engineering within the academic community, and the university became a centre of excellence in the area. Earthquake engineers still refer to books written as a result of the work at Canterbury, such as the one by Park and Paulay, as bibles.

I believe that Canterbury directly reaped the rewards of the work done then and recently. People don’t realise how lucky we have been thanks to active and ongoing research sponsored by a wide variety of professional bodies, including the Earthquake Commission (EQC), universities, GNS Science, the New Zealand Society for Earthquake Engineering (NZSEE) and BRANZ.

New Zealanders should also celebrate the professional ethos of those in our construction industry, including engineers, architects and contractors. I only fully appreciated the importance of a robust Building Code and transparent governance when I visited India after the Gujurat earthquake, and found people had paid good money for quality modern homes that had been so poorly designed and constructed. They were effectively deathtraps from day one.

In 1999, I led a group of New Zealand engineers, geologists and civil defence personnel to Turkey, a few weeks after the major earthquake there, to learn as much as possible to take back to New Zealand. I will never forget the devastation. Over 45,000 people are believed to have died and 500,000 were left homeless.

High standards

The contrast with the impact of the Canterbury earthquake could not be starker. I do think the early morning timing saved lives, but I believe that thanks to the high standard of construction techniques in New Zealand, we would have expected no more than 20 to 30 fatalities, and those largely from falling masonry.

I was horrified at the damage done to cars from falling bricks, and it really brought home to me how incredible it was that Canterbury residents came through it so (relatively) unscathed. Having said that, every quake has its unique and ostensibly strange characteristics – magnitude doesn’t necessarily correlate with the degree of damage.

An example of the learning gained from experiencing at first hand the impact of major seismic events around the world is the building assessment forms used in Christchurch. These were modified based on information collected from a trip to Padang after the earthquake there last year.

My colleague, seismic engineer Jitendra Bothara, said the intelligence gathered by the group was passed to the Department of Building and Housing as well as the NZSEE. And the leader of the same group was on the first flight to Christchurch after the earthquake to aid the Civil Defence team in managing the initial building assessments plan.

Building evaluation guidelines

The building evaluation system implemented on the first day by the city council followed the guidelines* first prepared by NZSEE about 15 years ago, and revised in August last year after the Gisborne earthquake.

I am proud that Civil Defence personnel and volunteers from industry organisations performed Level 1 evaluations across key areas of the city in the two days following the earthquake, and Level 2 evaluations during the subsequent week, using the system developed by voluntary committees over the years.

Overall, I have been impressed with the performance of our modern buildings. The feeling among my colleagues is that the recently constructed buildings they assessed have not experienced more than about 30% of the shaking they are capable of resisting. Commercial buildings built to the current Building Code should be capable of withstanding many similar-sized shakings to that experienced a week ago without significant structural degradation.

Need for review

Going forward, I think there is a need to review some aspects of building design and construction. There is some evidence that suspended ceilings and the services they hide have in some cases been damaged when there is no immediate evidence of high intensities of shaking in the rest of the building.

There are New Zealand standards for the seismic restraint of these elements which will be looked at afresh. We seem to have got it right for the building structure, and now we need to see if we can further reduce the secondary damage.

I believe more investment needs to be made in the future in promoting the importance of securing contents in homes.

Awareness of the effects of liquefaction is at an alltime high, and this needs to be maintained within the construction sector. At Beca, one of our electrical engineers was strongly encouraged by his structural engineering colleagues to invest $5000 in 85 fencepost piles for his new home which was being built in a known area of liquefaction risk. He has well and truly benefited from the advice.

A learning for me was the key role played by property managers in the CBD in the days following the earthquake. They controlled the speed at which tenants returned to their premises, barring entry until trip hazards had been fixed, fire exits cleared and lifts working, as well as managing queries from returned tenants asking about seismic gaps, hairline cracks, etc.

I was impressed by the professionalism of many in so quickly setting up crisis centres and systems to track staff, tenants and building inspections. Beca’s Christchurch office is based in the PricewaterhouseCoopers building which is managed by Colliers. Colliers set up in their boardroom and were well organised and resourced with excellent systems and administration staff. In my view, New Zealand needs to wake up to the importance of property managers in these situations for the future.

Grasping the nettle

In terms of overall preparation, I believe that Wellington is currently setting the standard in New Zealand, having grasped the nettle early. Christchurch has done a superb job after 4 September, but was definitely playing catch-up in evaluating buildings and remedial works before the earthquake.

It is appropriate to remind Aucklanders not to fall into the thinking of Cantabrians who have said so often after the earthquake that they thought Wellington would be the target of the next ‘decent’ earthquake. While the known seismic hazard in Auckland might be less than in Christchurch or Wellington, Ruaumoko might have some surprises for us yet.

In conclusion, my colleagues at Beca and from organisations around New Zealand who have spent hours of unpaid time on study groups and committees conducting post-quake analyses over the years are proud that our efforts have yielded such positive results. While the earthquake has been devastating for so many, it has also been an opportunity for New Zealanders (and our building practices) to shine.

This earthquake has humbled us all, touching lives from the most informed earthquake engineers to the boy racer I met in the deserted streets of central Christchurch four sleepdeprived days after the initial event. He stopped in the middle of the street, leaned through his open window, and said, “Thanks mate. You guys are doing a great job.”

Dr Richard Sharpe is the technical director of earthquake engineering for Beca in Wellington; he is a past president and fellow of the New Zealand Society for Earthquake Engineering and has been a keynote speaker at several international earthquake conferences; he was made a distinguished fellow of IPENZ in 2007 in recognition of his earthquake engineering contributions.

*The NZSEE Building Safety Evaluation Guidelines can be found at www.nzsee.org.nz