Brick buildings at risk of earthquake and aftershock damage

29 September 2021

Australia's infrastructure encounters an array of environmental hazards every year' from bushfires to cyclones and floods' but how equipped are these buildings in an earthquake?

According to CQUniversity Building Surveying and Built Environment Lecturer Dr Darryl O'Brien' the recent earthquake in Melbourne has reinforced the importance of the National Construction Code' particularly with the possibility of future earthquakes and aftershocks.

"The National Construction Code provides the minimum construction standards to prevent damage from a range of known hazards.

"There is also a specific Australian Standard for earthquakes that is used to identify the earthquake risk for an area and then describe the specific construction requirements."

He explained that when buildings are designed and built to the code requirements' they should be capable of withstanding earthquakes' but issues can arise when older buildings have not been built to current codes.

"The National Construction Code applies different design event magnitudes' called importance levels' to buildings based on the type of use and occupant characteristics. So' a hospital for example is designed to withstand a greater magnitude earthquake than a house.

"Larger issues arise when the existing building stock that was constructed before the code requirements.

"After the 2011 Christchurch earthquake' we actually saw older buildings demolished as it was not possible to make them safe from earthquakes."

While most buildings and homes constructed in the past few decades are designed to withstand earthquakes' Dr O'Brien explained that people should be cautious around older structures.

"Timber frame single-storey houses are more resilient to earthquakes; unreinforced brick or masonry is the most susceptible construction type in respect to earthquakes.

"As was seen in the recent Melbourne event and the larger Newcastle quake in the '80s. This form of construction suffered the most damage'" he said.

"Bundaberg is one such example where there are a lot of unreinforced brick buildings in public areas."

While only minor damage occurred along Chapel Street in last week's Melbourne earthquake' he cautioned that future earthquakes or even aftershocks could lead to further damage.

"If the initial quake weakened the structure' there could be a greater risk in the future that the public is unaware of."