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  • The importance of disaster-risk reduction in ensuring long-term sustainability of development and economic growth has gained increased awareness within the international development community, and thereby highlighted a need for a broad assessment of natural hazards across the Asia-Pacific region. A key component of this assessment involves qualifying, and ultimately quantifying, the frequency and potential consequences of large Volcanic Explosivity Index (VEI) of 4 or more volcanic eruptions in this region. The frequencies of large eruptions were determined from frequency-magnitude plots using eruption data provided by the Smithsonian Institution's Global Volcanism Program. However, calculated frequencies represent only minimum values. This is because roughly half of the volcanoes in the region have no eruption chronologies, the eruption record for the most part extends back only 400 years, and good records exist for only the last 180 years. A rough analysis was undertaken to estimate the populations likely to be impacted by large volcanic eruptions, where 'impacted' refers to possible death, injury, building damage, loss of access to basic services, and failure of industrial/agriculture production. The following conclusions were made from frequency-impact plots: - Indonesia and the Philippines have the highest level of risk with respect to volcanic eruptions, in terms of total population impacted. - Volcanic disasters affecting populations of 100,000 or more can be expected at least every decade in Indonesia and once every few decades in the Philippines. - Both Indonesia and the Philippines, at current population levels, have the potential to experience volcanic disasters affecting at least 1 million people, at a rate of once and twice a century, respectively. - All of the countries for which results were obtained - Indonesia, Philippines, Papua New Guinea, Vanuatu and Tonga have the potential for a volcanic disaster that will impact at least 1% of the population, but at different rates: twice a century for Vanuatu, around twice a millennium for Indonesia and the Philippines, and around every millennium for Papua New Guinea and Tonga - Vanuatu has the potential for catastrophic volcanic disaster that seriously affects more than 5% of the population around once a millennium.

  • We report on an assessment of severe wind hazard across the Australian continent, and severe wind risk to residential houses (quantified in terms of annualised loss). A computational framework has been developed to quantify both the wind hazard and risk due to severe winds, based on innovative modelling techniques and application of the National Exposure Information System (NEXIS). A combination of tropical cyclone, synoptic and thunderstorm wind hazard estimates is used to provide a revised estimate of the severe wind hazard across Australia. The hazard modelling utilises both 'current-climate' information and also simulations forced by IPCC SRES climate change scenarios, which have been employed to determine how the wind hazard will be influenced by climate change. We have also undertaken a national assessment of localised wind speed modifiers including topography, terrain and the built environment (shielding). It is important to account for these effects in assessment of risk as it is the local wind speed that causes damage to structures. The effects of the wind speed modifiers are incorporated through a statistical modification of the regional wind speed. The results from this current climate hazard assessment are compared with the hazard based on the existing understanding as specified in the Australian/New Zealand Wind Loading Standard (AS/NZS 1170.2, 2002). Our analysis has identified regions where the design wind speed depicted in AS/NZS 1170.2 is significantly lower than 'new' hazard analysis. These are regions requiring more immediate attention regarding the development of adaptation options including consideration by the wind loading standards committee for detailed study in the context of the minimum design standards in the current building code regulations.

  • Climate change is expected to increase severe wind hazard in many regions of the Australian continent with consequences for exposed infrastructure and human populations. The objective of this paper is to provide an initial nationally consistent assessment of wind risk under current climate, utilizing the Australian/New Zealand wind loading standard (AS/NZS 1170.2, 2002) as a measure of the hazard. This work is part of the National Wind Risk Assessment (NWRA), which is a collaboration between the Australian Federal Government (Department of Climate Change and Energy Efficiency) and Geoscience Australia. It is aimed at highlighting regions of the Australian continent where there is high wind risk to residential structures under current climate, and where, if hazard increases under climate change, there will be a greater need for adaptation. This assessment is being undertaken by separately considering wind hazard, infrastructure exposure and the wind vulnerability of residential buildings. The NWRA will provide a benchmark measure of wind risk nationally (current climate), underpinned by the National Exposure Information System (NEXIS; developed by Geoscience Australia) and the wind loading standard. The methodology which determines the direct impact of severe wind on Australian communities involves the parallel development of the understanding of wind hazard, residential building exposure and the wind vulnerability of residential structures. We provide the current climate wind risk, expressed as annualized loss, based on the wind loading standard.

  • The Climate Futures for Tasmania (CFT) research project is the Tasmanian Government's most important source of climate change data at a local scale. The project has created fine-scale (14 kilometre) climate information for Tasmania by downscaling five global climate models (GCM-s) with two IPCC emission scenarios (A2 and B1) to generate climate information from 1961 to 2100. This new dataset is being used to interpret the impact of the changing climate on four main disciplines: General Climate, Water and Catchments, Extreme Events and Agriculture. As part of the extreme events component, Geoscience Australia is conducting severe wind hazard and risk studies in the Tasmanian region under both current and future climate conditions. In this paper we present severe wind hazard maps for Tasmania for current and future climate. The CFT fine scale climate simulations which provide high-resolution spatial detail of the wind speed (hourly maximum time-step mean wind speed used) were used. The methodology is described in an accompanying paper ('Dynamical downscaling of severe wind hazard: Methodology', in these proceedings).

  • Geoscience Australia (GA) is currently undertaking the process to update the Australian National Earthquake Hazard Map using modern methods and an extended catalogue of Australian earthquakes. This map is a key component of Australia's earthquake loading code. The characterisation of strong ground-shaking using Ground-Motion Prediction Equations (GMPEs) underpins any earthquake hazard assessment. We have recently seen many advances in ground-motion modelling for active tectonic regions. However, the challenge for Australia - as it is for other stable continental regions - is that there are very few ground-motion recordings from large-magnitude earthquakes with which to develop empirically-based GMPEs. Consequently, we need to consider other numerical techniques to develop these models in the absence of these data. Recently published Australian-specific GMPEs which employ these numerical techniques are now available and these will be integrated into GA's future hazard outputs. This paper addresses several fundamental aspects related to ground-motion in Australia that are necessary to consider in the update of the National Earthquake Hazard Map, including: 1) a summary of recent advances of ground-motion modelling in Australia; 2) a comparison of Australian GMPEs against those commonly used in other stable continental regions; 3) a comparison of new GMPEs against their intensity-based counterparts used in the previous hazard map; and 4) the impact of updated attenuation factors on local magnitudes in southeastern Australia. Specific regional and temporal aspects of magnitude calculation techniques across Australia and its affects on the earthquake catalogue will also be addressed.

  • SEVERE WIND GUST RISK FOR AUSTRALIAN CITIES - A NATIONAL RISK ASSESSMENT APPROACH Bob Cechet, Krishna Nadimpalli, Mark Edwards, Chitibabu Divi, Tina Yang, Augusto Sanabria, Craig Arthur, Nariman Habili, Neil Corby and Ingo Hartig Risk and Impact Analysis Group, Geospatial and Earth Monitoring Division, Geoscience Australia GPO Box 378, Canberra, ACT, 2601, Email. bob.cechet@ga.gov.au This presentation aims to provide an overview of the methodology and initial results from the analysis by Geoscience Australia of the risk that peak wind gusts pose to a number of Australian communities. It describes the progress made towards a national scale peak wind gust risk assessment for Australia. At present, these assessments cover residential development in both urban and adjacent rural regions of all Australian capital cities and some large rural centres. The current work program includes the consideration of the risk posed by severe wind to commercial and industrial structures and the assessment will be refined for both an improved understanding of Australian peak wind gusts and for climate change influences. This wind risk research forms part of Geoscience Australia's assessments of the potential losses to Australian communities from a range of sudden impact natural hazards. These assessments aim to define the economic and social threat posed by these hazards through a combined study of natural hazard research methods and risk assessment models. Hazards being considered include earthquakes, cyclones, floods, landslides, severe winds, storm surge and tsunami. The local wind effects on return period regional wind speeds were determined by assessing the effect of terrain at the structure height of interest, the shielding effect of up-wind buildings and the effect of topography. The estimation of the local wind speeds that would be equalled or exceeded within a given time period (commonly called return period wind speeds or return levels) were derived by combining the return period regional wind speeds with the local wind multipliers (terrain/height, shielding and topographic) for 8 cardinal directions on a 25 by 25 metre grid across each study region. The maximum wind value for all directions was sampled at each grid location and used to assess residential damage. This presentation explains the methodology employed by Geoscience Australia to evaluate the risk associated with peak wind gusts in Australian cities, including a concerted attempt to define the associated uncertainty with the predictions. Limitations with the present methodology are also examined. In particular, these results are thought to be useful as a guide to relative wind risk in the Australian region; however the absolute values are likely to be an overestimate. The production and future utilisation of an event-based hazard dataset for all regions of the Australian continent is discussed and illustrated by using case studies.

  • A study of the consistency of gust wind speed records from two types of recording instruments has been undertaken. The study examined Bureau of Meteorology's (BoM) wind speed records in order to establish the existence of bias between coincident records obtained by the old pressure-tube Dines anemometer and the records obtained by the new Synchrotac and Almos cup anemometers. This study was an important step towards assessing the quality and consistency of gust wind speed records that form the basis of the Australian Standards/NZ Standards for design of residential building (AS/NZS 1170.2:2002 and AS 4055:2006). The Building Code of Australia (BCA) regulates that buildings in Australia must meet the specifications described in the two standards. BoM has been recording peak gust wind speed observations in the Australian region for over 70 years. The Australia/New Zealand Wind Actions Standard as well as the wind engineering community in general rely on these peak gust wind speed observations to determine design loads on buildings and infrastructure. In the mid-1980s BoM commenced a program to replace the aging Dines anemometer with cup anemometer. During the anemometer replacement procedure, many localities had both anemometers recording extreme events. This allowed us to compare severe wind recordings of both instruments to assess the consistency of the recordings. The results show that the Dines anemometer provides higher severe gust wind speeds than the 3 cup anemometer when the same wind gust is considered. The bias varies with the wind speed and ranges from 5 to 17%. This paper presents the methodology and main outcomes from the assessment of coincident measurements of gust wind speed.

  • The annual cost of sudden onset natural hazards in Australia was estimated in 2001 to be more than 1.1 billion Australian dollars, and the cost of events since then indicates that ongoing efforts are required to manage the risks from bushfires, floods, tropical cyclones, storm surge, severe storms, earthquakes and tsunami in Australia. Tropical Cyclone Larry, which destroyed agricultural crops and property in North Queensland (April 2006), and the Hunter Valley floods (June 2007) are the latest events to each have caused more than a billion dollars of insured and uninsured damage, and they have triggered substantial government relief payments. In 2003 the Council of Australian Governments (COAG) published a review of natural disaster relief and mitigation arrangements in Australia, recommending the development and implementation of a national program of systematic and rigorous disaster risk assessments. The report advocated a `fundamental shift in focus towards cost-effective, evidence-based disaster mitigation. As a result, the Natural Disaster Mitigation Programme (NDMP) was implemented by the Australian Government in collaboration with the State and Territory Governments. The aim of the NDMP was to reduce the costs of natural disasters in Australia, including government disaster relief payments, by supporting risk assessment and mitigation efforts. Geoscience Australia has been engaged as a technical advisor as part of the programme, and has also undertaken a series of national risk assessments for a range of natural hazards. Geoscience Australia has also facilitated the development of a national risk assessment advisory structure and risk assessment framework. Significant progress has been made in developing methods, models and tools for application to impact and risk assessment studies. In this presentation we examine three risk/impact assessment models and associated case studies for earthquake, cyclone/severe wind and tsunami. Each risk/impact model consists of hazard, building and population exposure, and consequence/damage modules. The hazard component considers the probability of occurrence of events of different magnitudes (or categories) and locations, and the propagation of energy from the hazard source to sites of interest. The exposure information is captured in the National Exposure Information System (NEXIS), which captures key attributes of residential and commercial buildings, critical infrastructure, population statistics, and business information. Vulnerability models consider the relationship between hazard parameters (e.g., ground shaking, wind speed, or wave height and speed) and the resulting damage to buildings/infrastructure, and human casualties. Building damage is then linked to repair-cost models that have been developed using quantity survey data. Finally, the costs and repair times are used to evaluate direct and indirect economic impacts at a regional and national scale. Geoscience Australia is making these risk/impact assessment models and information available to the States and Territories and other stakeholders through the release of open source software, interoperable databases, web-based information access, and training of technical experts.

  • Evidence based disaster management enables decision makers to manage more effectively because it yields a better informed understanding of the situation. When based on evidence, the decision making process delivers more rational, credible and objective disaster management decisions, rather than those influenced by panic. The translation of fundamental data into information and knowledge is critical for decision makers to act and implement the decisions. The evidence from appropriate information helps both tactical and strategic responses to minimise impacts on community and promote recovery. The information requirements of such a system are quite comprehensive in order to estimate the direct and indirect losses; the short and long term social and economic resilience. Disasters may be of rapid onset in nature like earthquakes, tsunamis and blast. Others are slow onset such those associated with gradual climate change. Climate change has become a real challenge for all nations and the early adaptors will reduce risk from threats such as increased strength of tropical cyclones, storm surge inundations, floods and the spread of disease vectors. The Australian Government has recognised the threats and prioritised adaptation as an opportunity to enhance the nation's existing infrastructure and thereby reduce risk. A thorough understanding of the exposure under current and future climate projections is fundamental to this process of future capacity building. The nation's exposure to these increased natural hazards includes all sectors from communities to businesses, services, lifeline utilities and infrastructure. The development of a National Exposure Information System (NEXIS) is a significant national capacity building task being undertaken by Geoscience Australia (GA). NEXIS is collecting, collating, managing and providing the exposure information required to assess multi-hazard impacts.