17 October 2013 — An earthquake hit Sydney last week. The magnitude 3.5 quake hit the Campbelltown area at approximately 7.15 am on Tuesday 8 October.
Adjunct Professor Kevin McCue from the Australian Seismological Centre, and former president of the Australian Earthquake Engineering Society, told The Fifth Estate he was surprised the earthquake didn’t gain more media coverage, particularly seeing its epicentre was only 30 kilometres from a “critical facility” – the Lucas Heights nuclear reactor.
Mr McCue is concerned Australia is not taking the threat of a major earthquake in built-up urban areas seriously, and says most buildings in Australia are not adhering to the Australian Standard AS 1170.4 (2007).
The 2007 Australian Earthquake Loading Standard states that most structures have to be designed to ensure minimum levels of robustness against earthquakes, however, Mr McCue gave The Fifth Estate multiple examples of buildings that had not been designed to this standard.
One example was a set of flats built in Sydney with a thin machine-made load-bearing brick. He said walls with these bricks were not supposed to be used above three storeys. The block of flats, he said, was seven storeys.
There were similar cases he’d seen in Perth, too.
Unreinforced masonry structures like this were a disaster waiting to happen, Mr McCue said. An earthquake could lead to the collapse of these bricks, leaving basically a frame.
“A stiff structure when it loses all those bricks becomes a soft structure,” he said, risking collapse.
Another surprising example was from his time at Geoscience Australia, the body responsible for monitoring earthquakes.
Back in the late ’90s when the organisation’s building was being constructed (back then it was known as the Australian Geological Survey Organisation), Mr McCue said he was asked by the construction company whether there were any special requirements, and he said that earthquake code provisions should be applied.
The building was designed with four parts connected by a central atrium. After construction, Mr McCue found that only the section of the building he was working in was designed to withstand earthquakes and that “tortional irregularity” meant the building was now more susceptible than if none of it were designed to withstand an earthquake.
Recently, Shivan Subramaniam, chairman and chief executive of FM Global, said he too was concerned commercial office blocks in Australia were at risk of earthquake damage.
Australian offices were lagging behind their US counterparts in the installation of risk-reduction technology, such as automatic valves to shut gas pipes in the event of an earthquake, the Australian Financial Review reported him saying.
These valves were put in as standard after the San Francisco earthquake of 1906, where the largest losses came from fires started after the earthquake had hit.
What’s the risk of a major earthquake in Australia?
Australia is classified as a low to moderate seismic region subject to low probability, high consequence, earthquake events up to magnitude 7.
However, there is a common belief Australia is immune to serious earthquakes because it is located within a tectonic plate.
This is not at all true, Mr McCue said.
While 90 per cent of earthquakes occur on plate boundaries, 10 per cent occur within the plate, and these earthquakes can cause major damage, he said.
The 6.3 magnitude Christchurch earthquake of 2011, for example, could be described as an intraplate earthquake, Mr McCue said.
“Newcastle was only a 5.6 earthquake, and we have one of those every two or three years,” he said. “An earthquake the size that hit Christchurch happens approximately every 10 years.
“Australia is a big country and the probability of an earthquake hitting a built up area is quite small, however the probability of Christchurch getting hit was also small.”
There was “no obvious reason why Sydney couldn’t be directly hit”, Mr McCue said.
Insurers tend to agree
A paper published in 2008 said that reinsurance companies rated an earthquake in Sydney as one of the top 20 risk exposures globally.
It said the Australian insurance industry was very aware of the earthquake risk and annually transferred roughly $200-300 million to reinsurance companies overseas in order to reduce exposure.
Global insurer QBE recently said it viewed a Sydney earthquake as the single biggest risk to its Australian operations, and that estimates of insured losses could total $20 billion, though as the Christchurch earthquake had insured losses of $US13 billion, the figure may be on the low side.
According to the Australian Building Codes Board, earthquakes comprise about 13 per cent of total natural disaster costs in Australia.
The 5.6 magnitude event in Newcastle in 1989 caused over $2 billion in damage.
What needs fixing?
The main concerns for Mr McCue were “Level 4” buildings such as hospitals and emergency services, which needed to survive an earthquake and also remain operable, and “Level 3” buildings, particularly schools, where large numbers of people congregate.
Next were the unreinforced masonry structured mentioned above.
An audit of the most critical infrastructure, namely hospitals and schools, was desperately needed to see which needed strengthening, he said.
Why aren’t we building to standard?
Mr McCue said there were a number of factors why standards weren’t being built to.
Primary among those was education.
“The problem is a lack of education,” he said, pointing to the fact there was no undergraduate course featuring earthquake engineering in Australia, with another qualification having to be done to gain knowledge.
In an recent Arup Thoughts piece, seismic engineer Kubilây Hiçyilmaz said conceptualising earthquake engineering as a specialist activity was detrimental.
“In many countries where it’s still an emerging discipline, civil and structural engineers are not routinely taught about structural dynamics and earthquake engineering,” he said.
“To me, that’s like going to medical school and not learning about antibiotics.”
Another challenge was a lack of qualified regulators, Mr McCue said. There were no building regulators that were experts in earthquake engineering, so it would be difficult for them to be able to judge whether buildings were compliant.
Building for earthquakes meant looking to see how buildings performed dynamically, Mr McCue said, a skill that was lacking in Australia.
A third problem was financial.
“Building owners want to cut costs,” Mr McCue said, noting there was general ignorance about the importance of meeting the standard and the costs involved.
The cost of meeting the earthquake standard has been estimated at just 0.05 per cent of “total building task”.
If a building were to fail in an earthquake and it was found not to be built to standard, however, we could see architects and builders taken to court, Mr McCue said.
“People need to know what risk they’re taking and I think in our country we don’t.”