Ben & Geoff will present at the Pacific Conference on Earthquake Engineering 2023 in Vancouver at the end of June.
After the Canterbury earthquakes in 2011, Ben Exton was a student shovelling silt from damaged Christchurch homes as part of the volunteer clean-up. Geoff Banks was a practising engineer visiting devastated families in their damaged homes and seeing first-hand the human impacts of that damage.
These personal experiences, combined with research on the impact of earthquake damaged homes, are the focus of the pair’s paper on the financial, environmental and health impacts of earthquake damage, which will be presented at the global conference next month.
“Visiting people in their homes and seeing the real impacts of the earthquakes and then advising them and their insurers as they resolve claims for years afterwards really brought home the human impacts for me,” says Geoff.
While seismic engineering has advanced enormously for larger buildings and infrastructure, the industry has not made as much progress on the resilience of low-rise homes to limit damage. This comes with a cost, the paper explains.
Repair costs can sometimes exceed the value of the property and may not be entirely covered by insurance. As many who lived in Christchurch following the 2011 earthquakes can attest, the repair process can be lengthy and stressful.
There are wider costs as well. The need for temporary accommodation results in a decreased housing supply, increased construction costs and disruption to businesses. Large numbers of displaced residents can result in lost productivity, unemployment and increased demand for social services. The paper argues that these can have long-lasting impacts on individuals, the economy and the community.
The environmental impacts of earthquake damaged homes include waste and carbon emissions. Eight million tonnes of debris was generated in Christchurch from demolition - and this figure doesn’t include all the home repairs. Hazardous materials, such as asbestos and lead-based paint, were present in many homes and required proper disposal to protect workers and the environment. The resources to rebuild include raw materials, energy and water - extraction, processing and transportation of these materials results in substantial carbon emissions.
The paper also details health impacts of earthquake damage to homes - across physical health, exposure to hazardous materials, and mental health. It points to Otago University research showing that Cantabrians who experienced serious adversity, both through earthquake events and following consequences, were 40% more likely than those living outside the region to have at least one of several kinds of disorder including: major depression, post-traumatic stress disorder, or anxiety disorder.
The current state of earthquake damage-resilient home design varies across the Pacific Rim. In New Zealand there have not yet been formal retrofitting or low-damage incentive schemes for residential homes, but in Japan damage protection is much more common. Around 7% of homes less than a decade old have been built or retrofitted with systems or devices to minimise damage, incentivised by insurance reductions there. On the west coast of Canada and the USA, incentive schemes like the Earthquake Bolt & Brace (EBB) Scheme are making progress.
Just like seatbelts have become a ubiquitous safety feature in cars, the authors argue that by investing in earthquake-resilient, low-damage homes, we don’t only help protect the lives and well-being of residents in the Pacific Rim but also contribute to long-term environmental sustainability and affordability of the region's housing sector.