1Geoscience Australia, Cnr Jerrabomberra Ave and Hindmarsh Drive, Symonston ACT 2609
Dozens of tsunamis have been observed in Australia. Most were small, but the larger events generated hazardous waves and currents at the coast, as well as locally significant land inundation. To inform risk mitigation for this relatively rare hazard, we would like to know: Where are tsunamis likely to occur? How big? How often? How confident can we be? Probabilistic Tsunami Hazard Assessment (PTHA) provides an approach to answering these questions. It involves numerically simulating a large number of hypothetical tsunami scenarios from generation (typically by earthquakes) through to land inundation around the site of interest, as well as modelling of scenario frequencies based on historical data, physical theory and statistics. Advancements in HPC, and in the accurate measurement of coastal elevation over large spatial scales, are making it increasingly practical to conduct PTHA over large areas at high spatial resolutions. However, PTHA methodologies are not yet standardized and core scientific questions still need to be resolved: How should hypothetical earthquake-tsunamis be modelled to minimise biases in comparison to real tsunamis? How well do random tsunami scenarios represent historical events? How should uncertainties in the rates of large earthquakes be represented? This presentation will cover recent work on these questions by Geoscience Australia, focussed on better understanding Australia’s earthquake-tsunami hazard.
Gareth Davies works for Geoscience Australia on a range of coastal hazards projects, with a particular focus on tsunami hazards. He supports tsunami risk management in Australia via advice to cross-jurisdictional groups with emergency management responsibilities; is co-chair of the science working group of the Joint Australian Tsunami Warning Centre (in collaboration with the Bureau of Meteorology); and contributes to the Indian Ocean Tsunami Warning and Mitigation System.