The Earthquake Engineering Society has shaken up Australian beliefs by revealing that a 6.2 magnitude earthquake – the size of New Zealand’s destructive 2011 Christchurch earthquake – happens in Australia every 10 years.
“Australians are unaware of the frequency with which an earthquake of this magnitude occur in our country," said Dr Paul Somerville, president of the Earthquake Engineering society said at a conference recently. "It is a rare but foreseeable scenario.”
“The impact of such an earthquake on any one of our cities would be devastating given that few modern buildings in Australia are designed to adequately resist the ground motion arising from such large seismic events. The risk is even greater to older buildings.”
In Christchurch, many people were killed by falling masonry, especially parapet walls, and that is also a very likely scenario in Australian cities. Many were also killed in the collapses of poorly designed concrete frame buildings.
Somerville said government, city councils and their engineers all have an important role to play in identifying risks and leading response and recovery plans.
Despite earthquakes occurring infrequently, the risk, as assessed by the insurance industry, is high, given the high density and vulnerability of city buildings.
“Councils should foster an environment in which new construction follows design procedures and construction practices that provide the robustness and resilience that buildings require to withstand earthquakes,” Somerville said.
“Council Engineers should identify and foster the repair of hazardous buildings, especially schools and hospitals; establish good communication links with Emergency Management Australia; compile a list of trained Urban Search and Rescue engineers in their area; and make plans for earthquake response and recovery.”
He added that the possibility of a large earthquake occurring in an Australian city is “very real.”
“The minimal costs of improving earthquake safety in our buildings are dwarfed by the massive economic losses and loss of life that could occur in Australian cities should we ignore the risk,” he noted.
Newcastle City Council marks next month the anniversary of the destructive earthquake that hit there 25 years ago.
The 5.6 magnitude earthquake flattened buildings across the city and left 13 people dead. Hundreds of buildings had to be demolished and repairs went on for years, costing the city an estimated $4 billion.
The most seismically active areas in Australia are said to be in Victoria's Gippsland, the Adelaide Hills and east of Perth in the wheat belt.