Canberra is the Australian city most at risk of devastation during an earthquake

The nation’s capital is the city with the highest earthquake hazard potential in Australia should one hit on the major fault lines running through Canberra.

Canberra has been given the unfortunate title of the city most at risk of devastation should an earthquake happens on one of the two major fault lines running near the nation’s capital.

Cities and towns in Australia’s east rattled after a magnitude 5.9 earthquake hit regional Victoria on September 22.

Except for a few reports of property damage in Melbourne, the damage from the earthquake was relatively minor rather than a full-blown natural disaster as the epicentre was in regional Victoria.

With the entire Australian continent neatly contained on a single tectonic plate, earthquakes are relatively rare yet last month’s earthquake was a reminder the earth is still moving.

What might come as a surprise to many Canberrans is that it is nestled between two active fault lines with the potential of hosting catastrophic earthquakes.

The Mansfield VIC earthquake has been adjusted to 5.9 (Mw). A 4.0 (Mw) aftershock was recorded 15 minutes after the initial event. GA senior seismologist Jonathan Bathgate says that frequent aftershocks may be felt across SE 🇦🇺. Fill a felt report.👉 https://t.co/7FHfgUNeR6pic.twitter.com/1vmuWO6qdB

— Geoscience Australia (@GeoscienceAus) September 22, 2021

Canberra was named as capital city with highest earthquake hazard potential in Australia in Geoscience Australia’s latest National Seismic Hazard Assessment.

Geoscience Australia senior seismologist, Dr Trevor Allen, said the assessment weighed up the likelihood of earthquakes occurring and the potential ground motion impacts if an earthquake happened.

Dr Allen said the main factor for Canberra’s heightened hazard risk was its proximity to the Lake George fault to the city’s east and Murrumbidgee fault to the west.

“Lake George is one of Australia's most active fault lines,” he said.

“The Lake George fault stretches from just west of Goulburn to south of Queanbeyan.

“A fault that large could potentially host a magnitude 7earthquake on it.

“That’s about 10 times stronger than last month’s earthquake.

“(However) those very large earthquakes are exceedingly rare, we are talking about tens to hundreds of thousand years in recurrence.”

Earthquake damage in Melbourne

Yet Dr Allen stressed Canberra’s hazard potential is not a cause for alarm.

“We need to put this threat into perspective,” he said.

“Canberra still possesses a relatively low seismic hazard on a global scale relative to cities like Wellington, Tokyo, or Los Angeles.”

While the Lake George fault has the potential to host a magnitude 7 earthquake, Dr Allen said it wasn’t the most probable outcome.

“It’s more likely that Canberra would experience a smaller earthquake closer to the city that is potentially damaging, and that might occur at a fault that we don’t know about,” he said.

Dr Allen said Canberra’s biggest safeguard against earthquake devastation is building our city safely through adherence to adequate building codes.

“Even though the building code did come in 1993, there’s a lot of heritage and legacy structures that were built before this time that are potentially vulnerable,” he said.

“There may be retrofit opportunities to bring some of these buildings to code standard but unfortunately this is also very expensive.”

September’s earthquake also highlighted a lack of earthquake safety literacy among Australians.

“Following the recent Victorian earthquake, we received about 43,000 responses from the public,” Dr Allen said.

“One of the questions was ‘how did you react in the earthquake?’ and about 50 per cent of the people who responded said they either tried to exit the building or go to the doorway.

“This means the shaking was significant enough that they did try to take action but we (advise against) those two options.”

The Rawson #earthquake is the biggest to hit VIC in the modern instrumental era. We have received more than 40,000 reports from people who felt this earthquake – which is a new GA “Felt Report” record. Read more: https://t.co/PaAANLL3Gepic.twitter.com/4MoSh761Cl

— Geoscience Australia (@GeoscienceAus) September 23, 2021

Instead, Dr Allen recommends people “drop, cover and hold on” during an earthquake.

“Drop to the ground, try to get underneath a sturdy table or desk, and hold on until the shaking stops,” he said.

“(If you can’t get under a table) move away from heavy furniture that may pose a toppling risk.

“Try to move to a wall away from windows and cover your head until the shaking stops.”

Mr Allen said running out of buildings was not necessary as most modern buildings are unlikely to collapse.

He said most injuries caused by earthquakes occur when furniture, or non-structural fittings in buildings, such as airconditioning units and hanging lights, topple over.

“We’re never going to be able to predict earthquakes or stop them,” he said.

“Earthquakes are a hazard we need to be aware of and we need to make sure our future society is resilient to them.”