Data product National Seismic Hazard Assessment (NSHA)
Defining Australia’s earthquake hazard
The NSHA defines variations in the level of earthquake ground shaking hazard across Australia. Having access to this data allows higher hazard areas to be identified, so mitigation strategies can be developed for at-risk communities, making them more resilient to seismic events.
Building damage in Melbourne following the 22 September 2021 earthquake in the Victorian High Country.
Introducing the NSHA
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The NSHA provides an improved understanding of the seismic hazard and its uncertainties for Australia, allowing communities to be better prepared for earthquake events.
Read the overview
It is a flagship product that informs public and private strategies for earthquake risk mitigation across the country. One of the fundamental uses of national-scale seismic hazard assessments is in national building codes and standards. Read more about its applications in the model overview.
Who is the NSHA for?
The NSHA provides essential evidence-based information to emergency managers, governments and the engineering sector to help them prepare for, mitigate against and respond to earthquake disasters.
Members of the insurance industry use the NSHA to better understand earthquake risk when pricing insurance and reinsurance premiums.
Emergency professionals use NSHA data when developing disaster management and evacuation plans, helping to reduce earthquake threat levels and improve community safety.
Australian Standards use seismic hazard information to ensure all applicable new buildings and infrastructure are built to withstand likely earthquake ground motions. It also informs investment decisions for the retrofit of existing and historic buildings.
NSHA18 hazard map indicating the mean PGA (expressed as a proportion of the acceleration due to gravity, g) for 10% probability of exceedance in 50-years on AS1170.4 Site Class Be.
How the NSHA works
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It consists of 19 independent seismic source models, which provide an understanding of the earthquake occurrence across Australia and its associated uncertainties.
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It uses the national fault source model, derived from the neotectonics features database, to model hazard contributions from known or likely neotectonic earthquake sources. This allows the ground-shaking potential of these known fault sources to be characterised.
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It uses the Moment Magnitude scale, providing a more physically based representation of an earthquake’s size. This ensures consistency between rates of earthquake recurrence and the likely ground-motions these earthquakes will generate.
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It uses expert elicitation to weight alternative models, drawing on the collective expertise of the Australian seismological community to quantify uncertainty.
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It uses Australian-specific formulas to revise historical earthquake magnitudes, leading to a reduction in hazard values in many Australian locations.
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It employs modern ground motion models developed for both the Australian and analogue tectonic environments that are calibrated using empirical datasets and numerical simulations.
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It quantifies the uncertainty of seismic hazard estimates to enable scientists, engineers and decision makers to explore the boundaries of the earthquake hazard and design risk mitigation efforts accordingly.
The combination of new data and scientific advances conforms with global best practice for undertaking national-scale earthquake hazard assessments.
Good to know
The science incorporated into the NSHA is state of the art and world leading. It had ongoing scientific review from distinguished international experts in Australia, Indonesia, New Zealand and the United States.
Geoscience Australia updates the NSHA on a regular basis. This allows the Australian Standards Committee to consider any changes in our understanding of seismic hazard in Australia based on the best available science, and decide whether the Standard needs to be amended to reflect this.
Looking Forward
Geoscience Australia will continue to update the NSHA, as we recognise the importance of incorporating best practice and evidence-based science to keep Australian communities as safe as possible from earthquake events. We still have a lot to learn about earthquake hazard in Australia, but the field of science and technology is constantly evolving and improving, and the NSHA will continue to reflect these advancements.
Case study Retrofitting Melbourne’s buildings to withstand earthquakes
How Geoscience Australia demonstrated the effectiveness of a mitigation program against building-related earthquake risk.
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How we support your sector
Our natural hazard resources can help your organisation be better prepared
Emergency managers
We offer a range of scientific tools to help emergency services plan and prepare for natural hazards, with the goal of reducing their impact when they do occur.
Government
Our scientific community safety resources can help inform robust government policy making with an evidence-based understanding of natural hazards.
Infrastructure
Our scientific tools and resources can help the infrastructure industry understand the exposure and vulnerability developments may have to natural hazards.
