You could be forgiven for thinking the risk of seismic activity in Australia is irrelevant. However, a look at the data suggests earthquakes may be more common than you think. According to recent research from Geoscience Australia, there has been a magnitude 2.0 earthquake in Australia everyday for the past decade.
While magnitude 2.0 is no cause for concern, we also experience Newcastle size quakes on a more frequent basis than many Australians realise. One reason why seismic activity is often overlooked in Australia is because the size of our country, relative to population, means many earthquakes occur in less populated areas and therefore go unnoticed by most residents. But, that doesn't mean they aren't happening.
On average Australia experiences a Newcastle size earthquake of magnitude 5.5 or higher every two years. Australia sits well within the Indo-Australian tectonic plate. The seismic activity we experience is the result of internal plate stresses and sub-faults, which are not well understood and difficult to predict. This means that earthquakes can occur anywhere in Australia, not just along known fault lines. If one of these higher magnitude earthquakes were to occur in an urban centre or business district in Australia, the results could be catastrophic.
Every 5-10 years there is a potentially disastrous earthquake of magnitude 6.0 or higher (www.ga.gov.au), equivalent to the devastating 2011 Christchurch earthquakes. The graphic above shows Australian earthquakes up to 2011.
There is sound reason behind the Australian Codes being updated to include seismic restraint of services in Importance Class 4 Buildings. It is possible for Australia to experience a Christchurch equivalent earthquake in any of our major cities. If important buildings (such as hospitals), and their services are not designed to withstand such forces, the human and economic toll will be severe. Further to this, non-structural elements, in particular, have been shown to account for around 70% of damage costs following an earthquake. There are economical ways to mitigate the tangible and non-tangible costs associated with this hazard.
At KUSCH Seismic we are committed to engineering maximum seismic resilience for minimum overall cost to ensure a safer Australia for many years to come. To find out how we can help you meet compliance on your next project, give us a call today.