National Seismic Hazard Assessment (NSHA)

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 given 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 and prioritised for the development of mitigation strategies so communities can be more resilient to earthquake events.

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 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's 2012 National Seismic Hazard Assessment is freely accessible and is available to use.

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.

This assessment has significant improvements in both the data sets and models used compared to previous national-scale hazard assessments. The improvements include:

  • An additional 20+ years of earthquake observations.
  • Improved methods of declustering earthquake catalogues and calculating earthquake recurrence.
  • Ground motion prediction equations (i.e. attenuation equations) calibrated using instrumentally recorded ¬†ground motions rather than macroseismic intensity observations.
  • Revised earthquake source zones implementing a multi-layer model.
  • Improved maximum magnitude earthquake estimates based on palaeoseismology.
  • The use of open source software for undertaking probabilistic seismic hazard assessment, which promotes testability and repeatability.

Download  

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.

Geoscience Australia will be releasing the 2018 NSHA in September. To be notified directly of its release, please email hazards@ga.gov.au.

The underlying data used to inform the 2018 NSHA has increased since the 2012 assessment, as has our confidence in certain modelling decisions (e.g. magnitude adjustments and conversions). 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.