Shaken not stirred: Top End ground shake strength ‘higher than previously understood’

A new study has revealed Darwin as an area with higher risk of strong ground shaking ‘than previously understood’. Find out why.

Darwin is on shakier ground than ever before as new information reveals the previous understanding of seismic sciences in the Top End was only the tip of the iceberg.

While earthquakes more often or of a higher magnitude are not in the near future for the Northern Territory, a new study has revealed the scientific understanding of how strong ground shaking is in the Top End doesn’t match what’s felt during an earthquake.

Geoscience Australia has released the first update to the National Seismic Hazard Assessment since 2018, identifying Darwin as an area where there is a higher risk of strong ground shaking.

Senior Seismologist Trevor Allen said the new assessment was based on updated data, models, and insights, collected from field surveys and earthquake catalogues, as well as from people who have felt an earthquake.

Senior Seismologist Trevor Allen examining seismic activity at Geoscience Australia. Picture: Supplied

“We have a large body of information that helps us understand the physical characteristics of earthquakes in Australia and how they impact the landscape around us,” Dr Allen said.

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

“We now know the level of risk in Darwin is higher than previously understood, because we have a much better understanding of how earthquakes in the Banda Sea - which are felt quite strongly in the area - affect the hazard.

“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 Darwin wouldn’t be experiencing stronger earthquakes all of a sudden.

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

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

The most recent earthquakes in the Northern Territory struck the Tiwi Islands on December 31, with two quakes reported within 12 hours of each other.

Over the past 20 years 14 seismic events have been recorded within a 200km radius from the Tiwi Islands epicentre, 16 if including the New Year’s Eve earthquakes.

Originally published as Shaken not stirred: Top End ground shake strength ‘higher than previously understood’