risk assessment
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FIRE NOTE 4 page article for the BCRC/AFAC information series.
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Australian building codes through the Australia/New Zealand Wind Actions Standard as well as the wind engineering community in general rely to a significant extent on the peak wind gust speed observations collected over more than 60 years by the Bureau of Meteorology (BoM). The current wind loading code and the performance of our infrastructure (residential, commercial, industrial and critical infrastructure) is based primarily on the Dines anemometer interpretation of the peak gust wind speed. In the early 1990's BoM commenced a program to replace the aging pressure tube Dynes anemometer with the Synchrotac and Almos cup anemometers. As of October 2008 only six Dynes anemometers remain in operation.
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The impacts of climate change, including sea level rise and the increased frequency of storm surge events, will adversely affect infrastructure in a significant number of Australian coastal communities. In order to quantify this risk, Geoscience Australia in collaboration with the Department of Climate Change and Energy Efficiency, have undertaken a first-pass national assessment which has identified the extent and value of infrastructure that are potentially vulnerable to impacts of climate change. We have utilised the best available national scale information to assess the vulnerability of Australia's coastal zone to the impacts of climate change. In addition to assessing coastal vulnerability assuming the current population, we also examined the changes in exposure under a range of future population scenarios provided by the Australian Bureau of Statistics. Continuation of the current trend for significant development in the coastal zone increases the number and value of residential buildings potentially vulnerable by 2100. We found that over 270,000 residential buildings are potentially vulnerable to the combined impacts of inundation and recession by 2100. This equates to a replacement value of approximately AUD$72 billion. Nearly 250,000 residential buildings were found to be potentially vulnerable to inundation only, which equates to AUD$64 billion. Queensland and New South Wales have the largest vulnerability (considering both value and number of buildings affected). Nationally, approximately 33,000 km of road and 1,500 km of rail infrastructure are potentially at risk by 2100. These results are influencing policy and adaptation planning decisions made by federal, state and local government.
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CSIRO climate change projections based on the IPCC Fourth Assessment Report indicate that Tasmania is one of the areas within the Australian region that will experience an increased magnitude of severe winds. This study utilises the Climate Futures for Tasmania (CERF project) fine scale climate projections which provide spatial detail of the increasing wind hazard derived through dynamic-downscaling utilizing a regional climate model forcing by 5 GCM's and two climate change scenarios (detailed by Sanabria and Cechet; this conference). These wind hazard estimates are used to determine the impact of the wind hazard on residential infrastructure in the Tasmanian region. Two regions of Tasmania were assessed, one in the north and one in the south. The risk assessment involves an understanding of exposure and wind vulnerability. Built environment exposure information was provided by the National EXposure Information System (NEXIS) developed by Geoscience Australia. Wind vulnerability relationships (relating gust wind speed to damage) were developed by Geoscience Australia through a series of expert workshops and the analysis of wind damage data. Return periods of exceedence loss levels were evaluated at buildings level across each region. These were subsequently used to evaluate annualised losses, which represent the average annual cost to the region of exposure to the wind hazard if viewed through a very wide window in time. Expressing the annualised loss as a percentage of the total reconstruction value gives a measure of the intensity of the risk to the studied community that is not as evident from simple dollar values. Risk projections for the Tasmanian region will be presented and the relationship between wind hazard and risk explored. These outputs will be crucial to informing climate change adaptation options regarding severe winds which should be of significant concern to planning, construction, emergency services and the community as a whole.
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Geographical information systems (GIS) have been used to model building flood damage in South East Queensland. The research shows that if a flood with a 1% annual exceedence probability (AEP) occurred simultaneously in all rivers in the region, 47 000 properties would be inundated, with about half of the properties likely to experience overfloor flooding. 90% of affected properties are located in the Brisbane-Bremer River system and the Gold Coast catchment. 89% of properties affected by flooding are residential. Nearly 60% of the residential flood damage is located in the Brisbane-Bremer River system, with damage estimated to be highest in those areas which historically have suffered high flood losses. Equivalent average damage per residential building is highest in the Gold Coast catchment. If the cost of the actual damages were to be spread among all residential buildings in South East Queensland, than the equivalent flood damage would be 1.09% damage from a flood with a 1% AEP.
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No abstract available
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The tectonic setting of Australia has much in common with North America east of the Rocky Mountains because stable continental crust makes up the whole continent. The seismicity is still sufficient to have caused several damaging earthquakes in the past 50 yr. However, uncertainties in the earthquake catalogue limit the reliability of hazard models. To complement traditional hazard estimation methods, alternative methods such as paleoseismic, geodynamic numerical models and high-resolution global positioning system (GPS) are being investigated. Smoothed seismicity analysis shows that seismic recurrence varies widely across Australia. Despite the limitations of the catalogue, comparisons of regional strain rates calculated from the seismicity are consistent with data derived from geodetic techniques. Recent paleoseismic studies, particularly those examining high-resolution digital elevation models, have identified many potential prehistoric fault scarps. Detailed investigation of a few of these scarps suggests that the locus of strain release is migratory on a time scale an order of magnitude greater than the instrumental seismic catalogue, consistent with Australia's low-relief landscape. Numerical models based on the properties of the Australian plate provide alternative constraints on long-term crustal deformation. Two attenuation models for Australia have recently been developed. Because Australiais an old, deeply weathered continent that has experienced little Holocene glaciation, it has very little material comparable to North American "hard rock" site classification. The combination of relatively low attenuation crust under widespread thick weathered regolith makes the use of ground-motion and site response models derived from Australian data vital for Australian hazard assessment. Risk modeling has been used to assess sensitivities associated with variations in both source and ground-motion models. Systematic analyses allow the uncertainty in these models to be quantifi ed. Uncertainty in most input models contributes a 30%-50% variation in the predicted loss. Where a city lies in a thick sedimentary basin, such as Perth, uncertainties in the behavior of the basin can result in a 500% variation in predicted loss.
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The Asia-Pacific region is home to well over half the world's population and is also the focus of some of earth's most intense geological activity. It is no surprise therefore that geological hazards, in particular earthquake and volcano hazards, make the Asia-Pacific region the scene of som e of the worlds most lethal natural disasters. While this is evident form a perusal of historical data relating to natural disasters, it is not clear how well such historical data can be used as a guide for high -impact events that might be expected in the future. This uncertainty is due to (1) how poorly extreme geological events having long recurrence intervals are represented in the relatively short historical record, and (2) the failure of the historical record to account for recent demographic trends, in particular the explosive growth of population in the Asia -Pacific region and its rapid urbanisation during the 20 th century. We present here two novel techniques for assessing the potential impacts of volcanic and earthquake events on human population in the Asia Pacific region. For volcanic risk, we have calculated the frequency of large eruptions, aggregated for the countries of the Asia -Pacific region, using data provided by the Smithsonian Institution's Global Volcanism Program. These eruption frequ encies have been combined with an analysis of population data for the region to estimate the average number of people who might be affected, in the broad sense of death, injury or loss of essential services, by a major volcanic eruption. For earthquake, risk, we have considered that the potential future high -impact events will be driven by the probability that an earthquake might occur in or adjacent to one of the many megacities of the Asia -Pacific region. Earthquake probabilities near megacities are cal culated from catalogue data, and these are combined with a rough criterion for damage based on earthquake ground motion, to asses potentially affected populations. We present preliminary results of these analyses, which suggest the potential for earthquakes and volcanoes in the Asia-Pacific region to cause future `mega-disasters', for which affected populations may be much larger than the numbers indicated by the historical record.
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This booklet identifies different types of volcanoes, and the dangers associated when volcanic materials are ejected in an eruption. It explains the importance of why we should study volcanoes and the effects these eruptions have on the atmosphere and climate. It also identifies where volcanoes are located in Australia. Student activities are included.
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As part of its response to the Indian Ocean tsunami of 26 December 2004, the Australian Government funded the establishment of the Australian Tsunami Warning System (ATWS). The ATWS has three objectives: (i) provide a comprehensive warning system for Australia, (ii) contribute to international efforts to establish an Indian Ocean Tsunami Warning System, and (iii) facilitate tsunami warnings in the Pacific Ocean. The ATWS has been issuing warnings for Australia since July 2006, and in 2007 started sharing advisories with other warning centres. It expects to begin issuing advisories directly to other countries during 2009. To be successful, an end-to-end warning system must develop mitigation strategies to prepare communities for tsunami. Mitigation strategies include taking steps to minimise the impact of a tsunami, eg., avoiding building in the likely inundation zone and building sea walls when this can't be avoided, and response procedures, such as evacuations, when an event occurs. The warning system must monitor for tsunami and issue warnings; and it must implement response strategies when a tsunami approaches the coastline and a recovery phase afterwards (Figure 1). In Australia, responsibility for these phases is shared by Commonwealth, State/Territory and Local Governments. Etc ...