A New Probabilistic Tsunami Hazard Assessment for Australia
221 Bouverie Street
Dozens of tsunamis have been recorded in Australia since 1900, with the larger events inducing locally significant inundation and hazardous marine currents. Overall these events have had a limited impact on people and infrastructure. Does this mean Australia is relatively safe from tsunamis – or have we just been lucky? In this seminar, Dr Davies will discuss the updated the national probabilistic tsunami hazard assessment (PTHA) produced by Geoscience Australia and how this contributes to a better understanding of the potential tsunami risk for Australia.
The PTHA contains a large suite of hypothetical earthquake-tsunami scenarios, each having a return period which is constrained with observed historical earthquake data and long-term plate tectonic motions. The tsunami propagation, being the way in which the tsunami moves across the ocean, is modelled globally for 36 hours, and results are stored at thousands of different sites in deep waters offshore of Australia. The PTHA provides a nationally consistent basis for tsunami scenario design, as required for coastal inundation hazard assessments.
The PTHA scenarios have been tested by comparison with deep ocean measurements from 18 observed tsunamis in 2006-2016. Key questions this seminar will address are whether the models can produce tsunamis that 'look like' the observations, and whether the statistical properties of the modelled tsunamis are reasonable. The seminar will draw upon results from the work by Geosciences Australia to highlight that to simulate realistic tsunamis, it is important to account for natural variations in earthquake size and slip, in addition to their magnitude. This seminar will provide the audience with an understanding of the tsunami hazard for Australia and the work of Dr Davies and Geosciences Australia contributes to more accurate modelling of tsunami risk.