Geoscience Australia has identified Darwin and parts of Victoria’s highlands as areas facing increased risk of strong ground shaking in its updated National Seismic Hazard Assessment.

The assessment, which has undergone its first update since 2018, details the level of earthquake ground shaking expected across the country, allowing governments, emergency management agencies and engineers to prepare and respond.

“Consistent with previous assessments, most areas around Australia are at low to moderate risk of experiencing strong ground shaking,” Geoscience Australia senior seismologist Trevor Allen said. 

“However, our understanding has changed for some regions, such as Darwin and the Victorian high country.”  

Dr Allen says the new assessment does not mean the areas will see “more earthquakes or stronger earthquakes all of a sudden”, but it outlines a new understanding of the risk.

He says the update draws on large amounts of data and modelling to detail the characteristics of an earthquake and the potential impacts.

“What has changed is how we understand and interpret the risk of earthquakes occurring and their consequent ground motions.

“The new assessment simply clarifies and improves our understanding of the risks that can be associated with this hazard.”

Earthquake risk in Darwin is higher than previously thought due to an improved understanding of how quakes in the Banda Sea affect the region.

“The shaking energy from Banda Sea earthquakes travels much more efficiently to northern Australia than it does to other places, even places that are much closer to the epicentre,” Dr Allen said.

Data from recent activity in Victoria, such as a 5.9-magnitude quake in 2021, reveals a slightly elevated risk level for the region.  

“Each earthquake is unique and provides us with more information that can be used to understand the likelihood and physical consequences of earthquakes in Australia,” Dr Allen said. “This information is then used to improve the accuracy of models and algorithms that underpin our hazard calculations.”

Geoscience Australia’s assessment also notes vulnerabilities in Australia’s built environment, with many older properties lacking appropriate quake loading standards.

See the assessment here.