ground motion model
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<div>Geoscience Australia, together with contributors from the wider Australian seismology community, have produced a new National Seismic Hazard Assessment (NSHA23), recommended for inclusion in proposed updates to Standards Australia’s AS1170.4. NSHA23 builds on the model framework developed for NSHA18, and incorporates scientific advances and stakeholder feedback received since development of that model. Key changes include: further refinement and homogenisation of the earthquake catalogue; revisions to the fault source model through inclusion of newly identified faults and revised activity rates on some faults; assessment of ground motion models through quantitative comparison against observations; and inclusion of a specific ground motion model for shaking from plate-boundary earthquakes in northern Australia. Expert elicitation was used to capture epistemic uncertainty surrounding model choices. The elicitation focused on decision points that sensitivity analysis had shown were more important for hazard, where new models had been developed, and where model choices had been controversial in NSHA18. Key questions included which catalogue to use as the basis for calculating hazard, the weighting of different source model classes (background, regional, seismotectonic, smoothed seismicity and smoothed seismicity with faults), and the selection and weighting of ground motion models for different tectonic regions. NSHA23 hazard results for capital cities show minor changes compared with NSHA18, with the exception of Darwin. Here the ground motion with a 10% probability of exceedance in 50 years increases significantly, a result that is attributed to inclusion of a new, more realistic ground motion model for plate-boundary earthquakes in this unique tectonic setting.</div><div><br>This paper was presented to the 2023 Australian Earthquake Engineering Conference 23-25 November 2023 (https://aees.org.au/aees-conference-2023/)</div>