In response to the Boxing Day tsunami in 2004 the Australian Government funded the creation of the Joint Australian Tsunami Warning Centre (JATWC) to mitigate the tsunami hazard to Australia. Within this system Geoscience Australia is responsible for locating and estimating the magnitude of earthquakes in the Australian region that have the potential to generate a tsunami. On 2 April 2007 a large earthquake (M 8.1) occurred in the Solomon Islands that generated a tsunami and caused severe damage and loss of life in the local area. Geoscience Australia detected the earthquake and issued an earthquake notification which resulted in the JATWC releasing a Tsunami Bulletin for the first time. The tsunami that reached the east Australian coast was small but proved that the systems put in place were effective for warning the Australian public of an approaching tsunami. Geoscience Australia has been developing tools to better characterise the earthquake source. Understanding the type of earthquake and accurately mapping the rupture improves the likelihood of describing the tsunami at the coast. As well as routinely estimating the magnitude Geoscience Australia complements this with estimations of the earthquake fault parameters (W-phase and Centroid Moment Tensor). Modelling of the rupture zone and the tsunami can then follow. This sequence of calculations has been carried out for the Solomon Islands earthquake and explains the tsunami amplitude that was observed on the coast. The modelling shows the earthquake ruptured for 200 km to the northwest with a maximum slip of 5.2 m.

The Attorney-General's Department (AGD) has supported Geoscience Australia (GA) to develop inundation models for four Victorian communities with the view of enhancing the tsunami planning and preparation capacity of the Victorian State Government. The four communities chosen were Lakes Entrance, Port Fairy, Portland, and Warrnambool. These locations were selected in collaboration with the Victorian State Emergency Service (SES) and the Australian Government, based on an initial review of low lying coastal communities, and an Australia wide nearshore tsunami hazard assessment [1]. Several tsunamigenic events were selected for modelling from the scenario database that was calculated as part of the national offshore probabilistic tsunami hazard assessment (PTHA) [2]. The events selected are hypothetical and are based on the current understanding of the tsunami hazard. Only earthquake sources are considered, which account for the majority of tsunami. The suite of events includes 'worst-case' or 1 in 10000 year hazard events, as well as a more frequent (1 in 100 and 1 in 500 year hazard) events. Source zones considered are the Puysegur Trench (all cases), the New Hebrides Trench and the Kermadec Trench (Lakes Entrance only), and the Java Trench and the South Sandwich Islands Trench (Port Fairy, Portland, and Warrnambool only). Based on the probabilistic tsunami hazard assessment [2], these source zones are considered as they make the most significant contributions to the offshore tsunami hazard for the study sites.

Real-time Earthquake Monitoring at the Joint Australian Tsunami Warning Centre From November 2006, Geoscience Australia began to monitor, analyse and alert for potentially tsunamigenic earthquakes that could threaten Australia's coastline, on a 24/7 basis. This ongoing role forms part of the Australian Tsunami Warning System (ATWS) that was announced in the Australian Government's May 2005 budget to complement the Indian Ocean Tsunami Warningand Mitigation System that was being implemented by the International Oceanographic Commission. The Joint Australian Tsunami Warning Centre (JATWC), as the operational arm of the ATWS, became fully operational in October 2008. It combines the efforts of Geoscience Australia's seismic measurement and analysis and the Australian Bureau of Meteorology's coastal and deep ocean sea level monitoring and modelling to produce timely tsunami warnings for Australia and the Indian Ocean region. A beneficiary of the setup of the JATWC was Geoscience Australia's ongoing role of reporting local Australian earthquakes, as it is now also able to function on a 24/7 basis; an upgrade to its earlier on-call arrangement. This paper describes the setup of Australia's tsunami warning capability and the methodology, systems and processes used to publish potentially tsunamigenic, local Australian and large international earthquake information. The paper will also highlight some of the future development activities to improve the accuracy and timeliness of Geoscience Australia's earthquake information.

The information within this document and associated DVD is intended to assist emergency managers in tsunami planning and preparation activities. The Attorney General's Department (AGD) has supported Geoscience Australia (GA) in developing a range of products to support the understanding of tsunami hazard through the Australian Tsunami Warning System Project. The work reported here is intended to further build the capacity of the Tasmanian State Government in developing inundation models for prioritised locations.

Keynote presentation to cover * the background to tsunami modelling in Australia * what the modelling showed * why the modelling is important to emergency managers * the importance of partnerships * future challenges

The high risk of natural disasters in developing nations has considerable implications for international aid programs. Natural disasters can significantly compromise development progress and reduce the effectiveness of aid investments. In order to better understand the threat that natural disasters may pose to its development aid program, AusAID commissioned Geoscience Australia to conduct a broad natural hazard risk assessment of the Asia-Pacific region. The assessment included earthquake, volcanic eruption, tsunami, cyclone, flood, landslide and wildfire hazards, with particular attention given to countries the Australian Government considered to be of high priority to its development aid program. Geoscience Australia's preliminary natural hazard risk assessment of the region aimed to help AusAID identify countries and areas at high risk from one or more natural hazards. The frequency of a range of sudden-onset natural hazards was estimated and, allowing for data constraints, an evaluation was made of potential disaster impact. Extra emphasis was placed on relatively rare but high-impact events, such as the December 2004 tsunami, which might not be well documented in the historical record. While a detailed risk assessment was well beyond the scope of this study, it was recognized that some understanding of the potential impact of natural disasters could be achieved through the simple means of developing appropriate overlays of population and hazard. For example, given an estimate of the frequency and magnitude (VEI) at which volcanic eruptions in a certain region occur, the populations impacted could be roughly estimated by considering the average population close enough to a volcano to receive a significant impact from ash fall.

The Joint Australian Tsunami Warning Centre (JATWC) provides 24/7 monitoring of earthquake and tsunami hazards affecting Australia and the Indian Ocean. The JATWC comprises Geoscience Australia, who undertake earthquake monitoring in Canberra, and the Bureau of Meteorology in Melbourne, who issue tsunami bulletins and monitor the sea level. Earthquakes are monitored at Geoscience Australia in real-time via a total network of over 260 seismic stations from both the Australian National Seismic Network (ANSN); and a collection of global stations, collaborating with other earthquake monitoring groups and organisations locally and internationally. This enables the quick detection and response to local, regional and global earthquakes, and assessment of its potential to generate a tsunami. If an earthquake is deemed to be tsunamigenic, earthquake information is used by the JATWC to deliver a tsunami warning based on the magnitude, depth and location of the earthquake combined with tsunami models. These warnings are supplemented with sea level information to validate the tsunami warning. Geoscience Australia also provides earthquake information and advice about Australian earthquakes and large international earthquakes to the Australian Government and general public. This is valuable for building safer communities in a world where the impacts of natural disasters can be far-reaching.

Tsunami inundation models are computationally intensive and require high resolution elevation data in the nearshore and coastal environment. In general this limits their practical application to scenario assessments at discrete communiteis. This study explores teh use of moderate resolution (250 m) bathymetry data to support computationally cheaper modelling to assess nearshore tsunami hazard. Comparison with high ersolution models using best available elevation data demonstrates that moderate resolution models are valid (errors in waveheight < 20%) at depths greater than 10m in areas of relatively low sloping, uniform shelf environments. However in steeper and more complex shelf environments they are only valid at depths of 20 m or greater. Modelled arrival times show much less sensitivity to data resolution compared with wave heights and current velocities. It is demonstrated that modelling using 250 m resoltuion data can be useful in assisting emergency managers and planners to prioritse communities for more detailed inundation modelling by reducing uncertainty surrounding the effects of shelf morphology on tsunami propagaion. However, it is not valid for modelling tsunami inundation. Further research is needed to define minimum elevation data requirements for modelling inundation and inform decisions to undertake acquisition of high quality elevaiton data collection.

The Natural Hazard Impacts Project (NHIP) at Geoscience Australia has developed modelling techniques that enable coastal inundation to be predicted during a tsunami. A Collaborative Research Agreement between Geoscience Australia and the Fire and Emergency Services Authority (FESA) was formed in 2005 to understand tsunami risk and inform emergency management in WA. Through this partnership a significant tsunami risk was identified in NW Western Australia, leading to the development of inundation models for several coastal communities in this region, including Onslow and Exmouth. Recognising the importance of this research to Geoscience Australia, FESA and the communities of Onslow and Exmouth, this year's graduate project was designed to assist the NHIP and to further strengthen ties with FESA and community organisations. The project had several distinct outcomes which can be divided into data acquisition and community interaction. High quality elevation data was gathered by GPS surveying in order to ascertain the quality of the Digital Elevation Model (DEM) that is currently used in inundation models. Improved accuracy in the elevation data allows the capture of subtle changes in topography that may not be present in the existing DEM and so may improve model accuracy. Secondly, ground-truthing of predicted inundation areas supplements the survey data, provides critical assistance in the production of accurate inundation models and potentially aids in the production of emergency plans. Prior to fieldwork a community-specific tsunami awareness brochure was designed and produced for Onslow. This brochure was presented to Onslow local emergency managers and FESA personnel, and subsequently to Emergency Management Australia and the Bureau of Meteorology. It has received widespread positive feedback, and consequently may provide a template for other community brochures in similarly vulnerable regions of Australia. Finally, graduates represented Geoscience Australia at several community meetings in Onslow where NHIP research was presented. These meetings provided insight into specific community concerns in the event of a tsunami and provided an opportunity for the attendees to ask questions about tsunamis and their impacts. Fortuitously this community interaction also led to the discovery of anecdotal evidence of past tsunami events in Onslow, including the tsunami triggered by the 1883 Krakatau eruption, a 1937 tsunami that may be attributed to an earthquake near Java, and the 1994 and 2004 tsunamis.

The major tsunamis of the last few years in the southern hemisphere have raised awareness of the possibility of potentially damaging tsunami to Australia and countries in the Southwest Pacific region. Here we present a probabilistic hazard assessment for Australia and for the SOPAC countries in the Southwest Pacific for tsunami generated by subduction zone earthquakes. To conduct a probabilistic tsunami hazard assessment, we first need to estimate the likelihood of a tsunamigeneic earthquake occurring. Here we will discuss and present our method of estimate the likely return period a major megathrust earthquake on each of the subduction zones surrounding the Pacific. Our method is based on the global rate of occurrence of such events and the rate of convergence and geometry of each particular subduction zone. This allows us to create a synthetic catalogue of possible megathrust earthquakes in the region with associated probabilities for each event. To calculate the resulting tsunami for each event we create a library of "unit source" tsunami for a set of 100km x 50km unit sources along each subduction zone. For each unit source, we calculate the sea floor deformation by modelling the slip along the unit source as a dislocation in a stratified, linear elastic half-space. This sea floor deformation is then fed into a tsunami propagation model to calculate the wave height off the coast for each unit source. Our propagation model uses a staggered grid, finite different scheme to solve the linear, shallow water wave equations for tsunami propagation. The tsunami from any earthquake in the synthetic catalogue can then be quickly calculated by summing the unit source tsunami from all the unit sources that fall within the rupture zone of the earthquake. The results of these calculations can then be combined with our estimate of the probability of the earthquake to produce hazard maps showing (for example) the probability of a tsunami exceeding a given height offshore from a given stretch of coastline. These hazard maps can then be used to guide emergency managers to focus their planning efforts on regions and countries which have the greatest likelihood of producing a catastrophic tsunami.