2023 – Updating the National Seismic Hazard Assessment: Philosophy and Implications

Trevor Allen, Jonathan Griffin, Dan Clark, Hadi Ghasemi, Phil Cummins, Reza Ebrahimi, Stacey Martin

Dam owners and operators must consider a range of hazards for the design and maintenance of infrastructure assets – including seismic hazards. In 2018, Geoscience Australia completed its National Seismic Hazard Assessment (the NSHA). This assessment used best-practice probabilistic approaches and produced considerably lower hazard forecasts than its predecessors. This assessment, and subsequent site- specific assessments conducted on behalf of the dam industry have yielded divergent estimates of hazard, causing confusion and concern amongst the dam engineering community. Herein, we unpack the rationale for these large discrepancies, and identify best practices for the treatment of earthquake catalogues when undertaking probabilistic seismic hazard assessments for extreme-consequence facilities. A short summary of the 2023 update to the NSHA is also provided.

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