This report describes the 2018 Probabilistic Tsunami Hazard Assessment for Australia (henceforth PTHA18). The PTHA18 estimates the frequency with which tsunamis of any given size occur in deep waters around the Australian coastline. To do this it simulates hundreds of thousands of possible tsunami scenarios from key earthquake sources in the Pacific and Indian Oceans, and models the frequency with which these occur. To justify the PTHA18 methodologies a significant fraction of the report is devoted to testing the tsunami scenarios against historical observations, and comparing the modelled earthquake rates against alternative estimates. Although these test provide significant justification for the PTHA18 results, there remain large uncertainties in “how often” tsunamis occur at many sites. This is due to fundamental limitations in present-day scientific knowledge of how often large earthquakes occur.

<div>This record links to tarred folders with simulation files used for a study on tsunami hazards in Tongatapu (eCat 146012) - DOI: https://doi.org/10.1093/gji/ggac140. </div><div><br></div><div>Access to this data will only be available by request via datacatalogue@ga.gov.au</div><div><br></div><div>The files were created using code here: </div><div>https://github.com/GeoscienceAustralia/ptha/tree/master/misc/monte_carlo_paper_2021. </div><div><br></div><div>This code should be read to understand the structure and contents of the tar archives. The simulation files are large and for most use cases you won't need them. First check if your needs a met via code and documentation at the link above. If the git repository doesn't include links to what you need, then it may be available in these tar archives. Contents include the datasets used to setup the model and the model outputs for every scenario. While the modelling files and code were developed by GA, at the time of writing, we do not have permission to distribute some of the input datasets outside of GA (including the Tongatapu LIDAR). </div><div><br></div><div>Access to this data will only be available by request via datacatalogue@ga.gov.au</div>

<p>The 2018 Australian Probabilistic Tsunami Hazard Assessment (PTHA18) was developed by Geoscience Australia to better understand Australia’s tsunami hazard due to earthquakes in the Pacific and Indian Oceans. The PTHA18 contains over a million hypothetical earthquake-tsunami scenarios, with associated return periods which are constrained using historical earthquake data and long-term plate tectonic motions. The tsunami propagation is modelled globally for 36 hours, and results are stored at thousands of sites in deep waters offshore of Australia. Average Return Interval (ARI) estimates are also provided, along with a representation of the associated uncertainties. ARI uncertainties tend to be large because of fundamental limitations in current scientific knowledge regarding the frequency of large earthquakes on global subduction zones. <p>The PTHA18 provides a nationally consistent basis for earthquake-tsunami scenario design, as required for inundation hazard assessments. The results and source-code are also freely available. The current paper aims to provide a short and accessible introduction to the PTHA18 methodology and results, while deliberately limiting technical details which are covered extensively in the associated technical report and code repository.

PTHA18 estimates the frequency with which tsunamis of any given size occur in deep waters around the Australian coastline. To do this it simulates hundreds of thousands of possible tsunami scenarios from key earthquake sources in the Pacific and Indian Oceans, and models the frequency with which these occur.

<div>An approach is presented to deriving onshore tsunami evacuation zones in Western Australia. The warning zones correspond to warning categories for distant earthquake tsunamis in the Joint Australian Tsunami Warning System. Onshore inundation hazards are computed by combining a detailed inundation modelled with earthquake-tsunami scenarios and rates from the 2018 Australian Probabilistic Tsunami Hazard Assessment. All modelled scenarios are assigned to JATWC warning categories and their onshore inundation extents are combined to produce preliminary maps, which are then limited to a very rare inundation event, and further manually adjusted to produce actionable evacuation zones. Although this procedure is conservative it leads to a large reduction in the size of the tsunami "land warning" evacuation zone compared to current advice. In the event of a land warning tsunami, this will enable better targeting of inundation prone areas by emergency services. <b>Citation:</b> Kendall, D., Davies, G., Brannigan, A., Gho, R., Whiney, J., Zanini, M.; Science-informed risk reduction for earthquake-generated tsunamis in Western Australia, Australian Journal of Emergency Management 39:4 - October 2024, p112-118.

<div>This is for submission to the 2022 ICCE Conference: https://icce2022.com/</div> This Abstract was submitted/presented to the 2022 International Conference on Coastal Engineering (ICCE) 04-09 December (https://icce2022.com/)

Numerical codes for probabilistic tsunami hazard assessment, available for download in github: https://github.com/GeoscienceAustralia/ptha

The 2018 Probabilistic Tsunami Hazard Assessmetn (PTHA18) outputs are can be accessed following the README instructions here: https://github.com/GeoscienceAustralia/ptha/tree/master/ptha_access

The present study reports on recent developments of the Indonesia Tsunami Early Warning System (InaTEWS), especially with respect to the tsunami modeling components used in that system. It is a dual system: firstly, InaTEWS operates a high-resolution scenario database pre-computed with the finite element model TsunAWI; running in parallel, the system also contains a supra real-time modeling component based on the GPU-parallelized linear long-wave model easyWave capable of dealing with events outside the database coverage. The evolution of the tsunami scenario database over time is covered in the first sections. Starting from the mere coverage of the Sunda Arc region, the current state contains scenarios in 15 fault zones. The study is augmented by an investigation of warning products used for early warning like the estimated wave height (EWH) and the estimated time of arrival (ETA). These quantities are determined by easyWave and TsunAWI with model specific approaches. Since the numerical setup of the models is very different, the extent of variations in warning products is investigated for a number of scenarios, where both pure database scenarios and applications to real events are considered.

A mini-poster on GA's capability in tsunami hazard modelling.