
This report is being provided to the Fire and Emergency Services Authority
(FESA) as part of the Collaborative Research Agreement (CRA) 
with Geoscience Australia (GA).
FESA recognises the potential vulnerability of the Western Australia
coastline to tsunamigenic earthquakes originating from 
the Sunda Arc subduction zone that caused the December 2004 event which
fortunately had no impact on Australia. 
However, there is historic evidence of tsunami events affecting the 
Western Australia coastline, \cite{CB:ausgeo}, 
and FESA has sought to assess
the relative risk of its urban and regional communities to the tsunami
threat and develop detailed response plans for a range of plausible events.

This report is the first in a series of studies which 
becomes a component of the suite of tsunami assessments for the North West
Shelf. 
Subsequent reports will not only
describe studies for other localities, they will also revisit these
scenarios as more refined hazard models with associated return rates
become available. In this report,
the methods, assumptions and impacts of a
single tsunami source scenario is described for the Onslow area in the 
North West shelf region. 
Onslow has a population of around 800
is part of the Shire of Ashburton in the Pilbara region of 
Western Autralia\footnote{http://www.pdc.wa.gov.au/region/political.htm}. 
Onslow supports
a variety of industries, including oil, gas, mining, cattle, 
fishing and tourism.

The report will outline the methods of modelling the tsunami from its 
source to its impact ashore and present the predicted consequences. 
Section \ref{sec:tsunamiscenario} provides
the background to the scenario used for this study. Whilst 
the return period of this scenario is unknown, it
can be be classed as a plausible event, see Section \ref{sec:tsunamiscenario}. 
Future studies
will present a series of scenarios for a range of return periods to 
assist FESA in developing appropriate plans for a range of event impacts. 
The details of the hazard modelling will not be described here, however,
the modelling technique to simulate the 
impact ashore will be discussed in Section \ref{sec:anuga} with data inputs
discussed in Section \ref{sec:data}. 
The inundation results will be shown and discussed in Section \ref{sec:results} 
with the impact modelling outputs shown in Section \ref{sec:impact}.
The report concludes with a summary of the results detailing issues
regarding underlying data and further model development.

