The 2018 Australian probabilistic tsunami hazard assessment: Hazard from earthquake generated tsunamis

This study estimates the frequency with which earthquake-generated tsunamis of any given “size” occur around Australia’s coastline. It represents an update of the previous national Probabilistic Tsunami Hazard Assessment (PTHA) conducted by Geoscience Australia (Burbidge et al., 2008a). Herein the latter study is referred to as the PTHA08, and the current study as the PTHA18. 

The main purpose of the PTHA18 is to provide nationally consistent inputs for inundation-scale tsunami hazard assessments in Australia. As with the PTHA08, the PTHA18 does not model tsunami inundation directly. However, the PTHA18 provides:  

1. Estimates of the frequency with which earthquake-tsunami waves above a given “size” occur at thousands of offshore sites (termed “hazard points”) around Australia. PTHA18 uses the “maximum stage”, which is the peak water-level above mean-sea-level (ignoring tides), as a measure of the tsunami “size”. This gives a rough indication of the potential of an event to produce inundation, although inundation is also affected by other aspects of the tsunami wave-train (e.g. period, polarity, details of the time-series, etc).  
2. Information on the relative importance of different earthquake-tsunami sources at each hazard point. 
3. A large database of earthquake-tsunami scenarios. For each earthquake-tsunami scenario, this includes: 

• Tsunami stage time-series (equivalently, water-level time-series) at thousands of “hazard points” offshore of Australia. 
• Tsunami initial conditions, in the form of an earthquake-generated water surface deformation. 

These outputs can be used to create tsunami scenarios for local-scale inundation hazard studies all around Australia, while retaining substantial national consistency among the results.