On 4 September 2010, a magnitude 7.1 earthquake struck the city of Christchurch and the surrounding region of Canterbury. This earthquake triggered a rippling effect throughout the region, with major earthquakes occurring on 26 December 2010, 22 February 2011, 13 June 2011, and 23 December 2011.
GNS Science, New Zealand’s leading seismic hazards research organization, says the ground accelerations in Christchurch on 22 February 2011 were the largest ever recorded for a New Zealand earthquake.
Although the September 2010 earthquake was of greater magnitude, it was the magnitude 6.2 earthquake of 22 February 2011 that led to the most deaths and damage to buildings. Tragically, a total of 185 people died, and many others suffered serious injuries.
These events led New Zealand’s government to form the Royal Commission of Inquiry into Building Failure Caused by the Canterbury Earthquakes. In October 2011, this commission released an interim report to “ inform early decision making on rebuilding and repair work that form part of the recovery from the Canterbury earthquakes ”.
These recommendations include the review of several New Zealand building standards to support the Canterbury rebuild. A final report is expected to be delivered to New Zealand’s Governor-General in November 2012.
The Government also established a new agency, the Canterbury Earthquake Recovery Authority, to lead and coordinate the region’s recovery.
Seismicity – developing a model
GNS Science has built a national seismic hazard model (NSHM) to predict the likely magnitude and frequency of major earthquakes. Developed for use in engineering design, NSHM was updated in 2010, before the September 2010 earthquake.
As well as modelling earthquakes on known faults, the updated model now allows for earthquakes on hidden faults up to a region-dependent maximum magnitude. For Canterbury, the new seismic model raised this magnitude from 7.0 to 7.2, just encompassing the magnitude 7.1 of the September 2010 earthquake.
Following the 22 February 2011 earthquake, GNS Science updated NSHM again, to account for the region’s active ongoing sequence of earthquakes. This led to an increase of the seismic hazard factor for Christchurch from 0.22 to 0.30, a large rise reflecting knowledge gained from the Canterbury earthquakes.
This type of information is now being fed into standards development and review processes. In building, fire protection, infrastructure, and risk management, Standards New Zealand is working with government, communities, and industry to ensure our standards reflect lessons learned from recent events. An important aspect of this work is also to identify what standards are working well.
Standards as building blocks
In New Zealand, many building standards are codified in the country’s building legislation and building code. For example, NZS 3604:2011, Timber-framed buildings, is a core resource for demonstrating compliance with the New Zealand Building Code.
Roger Shelton, Senior Structural Engineer, Building Research Association of New Zealand, and a member of several national and international standards committees including the one responsible for NZS 3604, says that codifying building standards in New Zealand legislation helps to ensure best practice. He says: “After the September 2010 and February 2011 earthquakes in Canterbury, early findings suggest most buildings that met current standards fared well.”
He cautions, however, that standards development is an iterative process: “Buildings that failed through the Canterbury earthquakes may have been built to standard at the time, but our knowledge continues to grow and, based on that knowledge, standards continue to evolve.
“And while standards development is important, it’s equally crucial that we ensure building professionals and consumers are well informed, and compliance with appropriate standards is achieved.
“One of New Zealand’s advantages is that we are a relatively small country where government, industry, and consumer representatives come together to solve issues. That allows a nimbleness and responsiveness to issues that might be harder to achieve in other parts of the world.”
The standards difference
Since the September 2010 earthquake, engineers and building experts have worked closely with government officials and Canterbury communities to identify issues that need to be addressed as Cantabrians begin to rebuild.
One expert is Chris Mak, who has over 25 years’ experience in fire protection, and currently manages the technical services business unit of insurance broker and risk management provider, AON New Zealand.
Chris Mak says that, overall, fire protection devices (such as sprinklers) that meet applicable standards performed well in the Canterbury earthquakes: “What we found after the September 2010 and February 2011 earthquakes is that most sprinkler system damages were attributed to building collapse, or mechanical damage by building element failures.
“Still, there have been several lessons learned for future fire protection standards development, including the collapse of about a dozen constructed water tanks and the potential need for some classes of buildings to have dedicated water supplies in case public water service is interrupted.”
In light of the earthquakes, the review committee of NZS 4541:2007, Automatic fire sprinkler systems, which Chris Mak chairs, is examining seismic provisions for water tanks and considering the inclusion of an appendix to the revised standard that introduces guidelines for steps to take following a natural disaster. The draft standard is expected to be released for public comment later in 2012, with publication of the final standard scheduled for March 2013.
Chris Mak says: “Another aspect of fire protection that needs further consideration is what happens if there is more than one disaster, for example if a major fire occurs after an earthquake. There is work to be done in assessing risk and analyzing costs and benefits to determine the level of fire protection that should be prescribed.”
The big picture
Beyond individual building issues, government officials and industry leaders are increasingly aware that resilience should be built into our overall systems to deal with extraordinary circumstances. In this context, resilience is defined as putting processes in place that help communities anticipate and, if necessary, respond and recover from disruptive challenges.
I see an important role for standards in addressing resilience both in New Zealand and internationally. Resilience standards could be developed in a similar way to how risk management standards, such as ISO 31000:2009, Risk management – Principles and guidelines, have evolved to offer organizations and communities a process-oriented approach to deal with complex and unexpected problems.
Standards New Zealand is currently considering resilience planning and many other areas of work.
The Canterbury rebuild is a huge challenge to New Zealand, and industry, government and local communities must continue to work together to ensure success. Extending beyond physically rebuilding Canterbury, this great effort has social, environmental, economic, and cultural dimensions, too.
Debbie Chin is Chief Executive of Standards New Zealand, a role she has held since 2007. Among her previous roles she has been Deputy Director, General Corporate and Information, Ministry of Health, and Advisor for the Department of Prime Minister and Cabinet. A Chartered Accountant, she is a graduate of Victoria University, Wellington.