The Asia-Pacific region experiences some of the world's most violent natural hazards, being exposed to earthquakes, volcanic eruptions, cyclones and monsoons. It is also home to many of the world's most populous megacities with large exposures to hazards. Indeed, government statistics reveal an annual average of 2.7 disasters a day in Indonesia alone. This high risk of natural disasters in developing nations has considerable implications for international aid programs, as disasters significantly compromise the achievement of development goals and the effectiveness of aid investments. Recognising this issue, AusAID requested Geoscience Australia to conduct a broad natural hazard risk assessment of the Asia-Pacific region. This assessment included earthquake, volcanic eruption, tsunami, cyclone, flood, landslide and wildfire hazards. A crucial aspect in the assessment of natural hazard risk is the metric used to define a past disaster and therefore the risk of future disasters. For this preliminary study, we used "significantly impacted population" as the risk metric. This deliberately vague metric is intended to capture the potential for human death, injury, and displacement, as well as prolonged loss of access to essential services and/or shelter, and/or significant damage to agriculture, horticulture and industry such that external assistance is required. However, future work in the Asia-Pacific region will need to be able to determine these vulnerabilities more accurately, considering, for example, the vulnerabilities of buildings and infrastructure in relation to building codes and construction practice, economic cost, and the spatial variability of the intensity of different hazard events. For this study, we determined the frequencies and magnitudes of a range of sudden-onset natural hazards and evaluated the potential disaster impact. Extra emphasis was placed on relatively rare but high impact events that may not be well reflected in the historical record, such as the 2004 Indian Ocean tsunami. We concluded that the potential is high for a natural disaster to seriously affect more than one million people in the Asia-Pacific region, with specific risks as follows: - Megacities in the Himalayan Belt, China, Indonesia and the Philippines are prime candidates for a million-fatality earthquake. - Hundreds of thousands may be seriously affected by volcanic disasters at least once a decade in Indonesia and once every few decades in the Philippines. - The population explosion in the mega-deltas of Asia (e.g., Bangladesh), combined with increasing vulnerability to climate change, indicates that a tsunami, flood or cyclone event significantly impacting tens of millions is likely. - Finally, many Pacific Island nations have a high potential for catastrophic disasters that may significantly impact large proportions of their populations, disasters that are most likely to overwhelm a local and national governments-response and recovery capacity.

The Joint Australian Tsunami Warning Centre (JATWC) was established in response to the Indian Ocean tsunami in 2004. The JATWC is a collaboration between Geoscince Australia and the Australian Bureau of Meteorology to provide tsunami warnings to the Australian public. This arcticle discusses the actions of the JATWC in response to the magnitude 7.4 earthquake that occurred south of New Zealand on the September 30, 2007. This earthquake generated a tsunami and a potential threat warning was issued for the Australian south east coast. The methods used to analyse the earthquake and the tsunami are examined as well as the future direction of operational capabilities in terms of tsunami modelling.

Most tsunami are caused by earthquakes that displace the water column by faulting the sea bottom or causing submarine landslides. Australia is surrounded by 8,000 km of active, earthquake-prone, plate margins. In Western Australia tsunami hazard is highest in the northwest facing the subduction zones of the Indonesian arc. Tsunami hazard along the eastern coast comes from subduction zones from the Solomon Islands in the northeast to the Puysegur Trench south of New Zealand. Images of the tsunami of 26 December 2004 impacting Thailand showed tsunami several metres high inundating large sections of shore line. Australia is much farther from the tsunami sources, and is more likely to face tsunami with smaller heights regionally but possibly increasing unpredictably to much larger heights locally. The Australian Government has funded the establishment of the Australian Tsunami Warning System (ATWS). End-to-end warning systems consider the development of mitigation strategies, monitoring for events, issuing warnings, and response and recovery phases after the event. The geosciences play important roles in several of these steps. Hazard mapping requires the study of the earthquake source regions (fault geometry, maximum likely earthquake magnitude and its probability, and estimates of the resulting tsunami height and direction). The development of mitigation strategies requires estimating the propagation of tsunami across the deep ocean, shoaling in the shallow waters near the shore line, the inundation of the land and the impact on people and infrastructure. The detection of earthquakes requires access to national and international seismograph networks that work interoperably in near-real-time, and algorithms for the rapid automatic determination of their locations (including depth), magnitudes and focal mechanisms. In cases where there are no sea level gauges between the source and coastline, the warning systems rely entirely on earthquake parameters. Published with the permission of the CEO of Geoscience Australia.

Palaeotsunami investigations can enhance our understanding of tsunami hazard in the Australian region, providing a means of assessing future risk. Previous researchers have suggested that at least six large tsunami impacted the NSW coast during the Holocene, some with run-up in excess of +100 m asl and inundation of 10 km inland. However, this evidence is contentious as it focuses on poorly understood rocky shoreline features and proposes tsunami signatures that have not been described in other parts of the world. If such evidence is substantiated, it has profound implications for the tsunami preparedness of the NSW communities. This study focuses on late Holocene coastal sedimentary records from backshore environments in NSW to develop an assessment of whether catastrophic marine inundation such as tsunami played a significant role in coastal evolution. The advantages of studying backshore environments are that a more continuous sedimentary record is likely to be preserved than on rocky shorelines and an estimate of tsunami recurrence can be obtained if several tsunamigenic units are found in sequence. Fifty cores from sixteen coastal water bodies in southern and central NSW were studied for evidence of past tsunami inundation. Potentially tsunamigenic sediment horizons were identified in some water bodies, which may be a result of localised submarine slump-induced palaeotsunami. However the small size and discontinuous distribution of these sedimentary units does not support the theory of "mega-tsunami" inundation. If such "mega-tsunami" had occurred, definitive evidence for them should be preserved on a wider scale in the backshore sedimentary record. This suggests that previous research for mega-tsunami on the NSW coastline needs to be re-evaluated.

Data package relates to tsunami modelling outputs that were used for the Catastrophic Working Group. This data relates is the underlying model development.

The aim of this document is to provide the Attorney General's Department (AGD) with an assessment of the nearshore tsunami hazard for Australia. This assessment is one of the tsunami capacity building initiatives of the AGD to support the tsunami planning and preparation initiatives of the States and Territories. It follows the national deep water probabilistic tsunami hazard assessment completed in 2008 [1] that showed that Western Australia has the highest offshore hazard, the east coast of Australia has a moderate offshore hazard, while the smallest hazard can be found off Australia's southern coast. The intent of this nearshore assessment is to add interpretative value to the deep water assessment by estimating the amplification factor that can be applied to convert the deep water hazard to the nearshore tsunami hazard at a number of Australian communities. Further, the deep water assessment did not provide data for most of Victoria, Northern Territory, the west coast of Cape York Peninsula in Queensland, or the north coast of Tasmania due to the shallow water of the Gulf of Carpentaria, and the Torres and Bass Straits. Therefore, this nearshore assessment provides these areas with a tsunami hazard assessment for the first time

The quality and type of elevation data used in tsunami inundation models can lead to large variations in the estimated inundation extent and tsunami flow depths and speeds. In order to give confidence to those who use inundation maps, such as emergency managers and spatial planners, standards and guidelines need to be developed and adhered to. However, at present there are no guidelines for the use of different elevation data types in inundation modelling. One reason for this is that there are many types of elevation data that differ in vertical accuracy, spatial resolution, availability and expense; however the differences in output from inundation models using different elevation data types in different environments are largely unknown. This study involved simulating tsunami inundation scenarios for three sites in Indonesia, of which the results for one of these, Padang, is reported here. Models were simulated using several different remotely-sensed elevation data types, including LiDAR, IFSAR, ASTER and SRTM. Model outputs were compared for each data type, including inundation extent, maximum inundation depth and maximum flow speed, as well as computational run-times. While in some cases, inundation extents do not differ greatly, maximum depths can vary substantially, which can lead to vastly different estimates of impact and loss. The results of this study will be critical in informing tsunami scientists and emergency managers of the acceptable resolution and accuracy of elevation data for inundation modelling and subsequently, the development of elevation data standards for inundation modelling in Indonesia.

It's hard to believe eight years has passed since the Great East Japan Earthquake occurred that devastated so much of Japan. In November, I was very fortunate to participate in a United National International Strategy for Disaster Reduction meeting in Sendai, which included two days of site visits to areas hit by the tsunami.

As the Australian plate slowly pushes under the Eurasian plate, massive stresses build up in the crust. These stresses also cause the Eurasian plate to be slowly forced upwards - part of the process that builds the mountains and volcanoes of Indonesia, as well as creating the many earthquakes felt in that region of the world each year. When the stresses get too great, the plates will suddenly slip causing massive movements in the seafloor. The part of the crust nearest to the fault zone rapidly moves upwards by a metre or so, lifting the entire body of water above it. A hundred kilometres away the opposite may happen: the seafloor drops and the ocean above it also falls. These two movements (the sudden rise and fall of the seafloor hundreds of kilometres apart), combine to cause a series of tsunami waves which move away from the line of the fault in both directions.

A detailed assessment of the impact of a far-field tsunami on the Australian coastline was carried out in the Steep Point region of Western Australia following the July 17 2006 Java tsunami. Tsunami inundation and run-up were mapped on the basis of eyewitness accounts, debris lines, vegetation damage and the occurrence of recently deposited fish, starfish, corals and sea urchins well above high-tide mark. A topographic survey using kinematic GPS with accuracies of 0.02 metres in the horizontal and 0.04 metres in the vertical recorded flow depths of between 1-2 m, inundation of up to 200 m inland, and a maximum recorded run-up of 7.9 m AHD (Australian Height Datum). The tsunami impacted the sparsely-populated Steep Point coastline close to low tide. It caused widespread erosion in the littoral zone, extensive vegetation damage and destroyed several campsites. Eyewitnesses reported three waves in the tsunami wave train, the second being the largest. A sand sheet, up to 14 cm thick and tapering landwards over 200 m, was deposited over coastal dunes. The deposits are predominantly composed of moderately well sorted, medium grained carbonate sand with some gravel and organic debris. A basal unconformity defines the boundary between tsunami sediments and underlying aeolian dune sand. Evidence for up to three individual waves is preserved as normally graded sequences mantled by layers of dark grey, organic-rich fine silty sand. Given the strong wind regimes in the area, and the similarity of the underlying dune deposits to the tsunami sediments, it is likely that seasonal erosion will remove all traces of these sediment sheets within years to decades.