National Seismic Hazard Assessment (NSHA)

Geoscience Australia has released a new National Seismic Hazard Assessment - the NSHA18. The NSHA18 is freely accessible and is now available to download.

Download NSHA18 

Geoscience Australia develops the National Seismic Hazard Assessment (NSHA) for Australia. The NSHA defines the level of earthquake ground shaking across Australia that has a likelihood of being exceeded in a given time period. Knowing how the ground-shaking hazard varies across Australia allows higher hazard areas to be identified for the development of mitigation strategies so communities can be more resilient to earthquake events.

Using the NSHA, decision makers can better consider:

  • What this could mean for communities in those areas and whether any further action is required
  • Where to prioritise further efforts
  • What this could mean for insurance and reinsurance premiums
  • Identify high and low hazard areas to plan for growth or investment in infrastructure.

The NSHA also provides key information to the Australian Government Building Codes Board, so buildings and infrastructure design standards can be updated to ensure they can withstand earthquake events in Australia. Geoscience Australia schedules the update to the NSHA to coincide with the update to the earthquake loading standard, so the committee can consider any changes to the seismic hazard risk of Australia, and whether the code needs to be amended to reflect this.

Geoscience Australia provides essential evidence-based information to government, industry and emergency managers around Australia to improve our communities' ability to prepare for, mitigate against and respond to natural disasters. Contact us at hazards@ga.gov.au if you need further information.

Geoscience Australia has released a new National Seismic Hazard Assessment - the NSHA18. The NSHA18 is freely accessible and is now available to download.

Download NSHA18 

Geoscience Australia has updated the NSHA to ensure it incorporates best practice and evidence-based science.

The underlying data used to inform this update has increased since the 2012 assessment, as has our confidence in certain modelling decisions (e.g. magnitude adjustments and conversions). Furthermore, in collaboration with the Australian seismological community, we have also updated the number of alternate seismic source models. As a consequence, the updated NSHA provides an improved understanding of the seismic hazard and its uncertainties for Australia, allowing communities to be better prepared for earthquake events.

Key features of the NSHA18 include:

  • Improved methodology for revising local magnitudes. The NSHA18 revises catalogue magnitudes using Australian-specific formulae. This in combination with other factors, lead to a reduction in hazard values across many Australian locations.
  • Converting the earthquake catalogue to the Moment Magnitude scale, to replace the 1930s-era Richter magnitude scale (ML). The Moment Magnitude scale provides a more physically-based representation of an earthquake's size. This ensures consistency between rates of earthquake recurrence and models that estimate the ground-shaking level for a given earthquake magnitude and distance from the epicentre.
  • Incorporating the national fault database to model hazard contributions from known, or likely neotectonic earthquake sources. This allows us to characterise the ground-shaking potential for Australian communities from these known fault sources.
  • Calculating hazard parameters using the Global Earthquake Model's OpenQuake-engine - an open source seismic hazard and risk modelling software engine developed using a rigorous, test-driven framework. This provides a modular and adaptable framework for hazard model calculations and the community-driven development enables Geoscience Australia to implement state-of-the-art methods and models into the NSHA.
  • Quantifying uncertainty of seismic hazard estimates by publishing the expected hazard and hazard fractiles. This allows scientists, engineers and decision makers to explore the boundaries of the earthquake risk and design mitigation efforts accordingly.
  • Using modern ground motion models developed for both the Australian and analogue tectonic environments that are calibrated using more abundant empirical datasets and numerical simulations.

The science incorporated in the NSHA18 is world leading and has had ongoing scientific review from distinguished international experts from Australia, Indonesia, New Zealand and the United States.

Geoscience Australia will continue to update the NSHA, as we recognise the importance of incorporating best practice and evidence based science, and there is still a lot to learn when it comes to earthquake hazard in Australia. Science and technology is constantly evolving and improving, and we need to ensure the NSHA reflects these advancements so we can ensure Australian communities are as safe as possible from earthquake events.

We welcome your feedback on the current NSHA. Send your feedback to hazards@ga.gov.au.