From 1 - 10 / 257
  • Severe wind damage accounts for about 40 percent of the total building damage observed in Australia during the 20th century. Climate change has the potential to significantly affect severe wind hazard and the resulting level of loss. W report on a nationally consistent assessment of severe wind hazard across the Australian continent, and also 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 modeling 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 modeling utilises both 'current climate' information and also simulations forced by IPCC SRES climate change scenarios (employed to estimate how the wind hazard may be influenced by climate change). Our analysis has identified regions where the design wind speed depicted in the Australian/New Zealand Wind Loading Standard (AS/NZS 1170.2, 2010) is lower than 'new' hazard analysis. In considering future climate scenarios, four case study regions are used to illustrate when the wind loading standard may be inadequate, and where retrofitting is indicated as a viable adaptation option at either the present or at a specified future time. The comparison of current and projected future risk, currently only considers direct costs (structural damage to houses) associated with severe wind hazard. A broader assessment methodology is discussed.

  • 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.

  • The tragic events of the Indian Ocean tsunami on 26 December 2004 highlighted shortcomings in the alert and response systems for tsunami threats to Western Australia's (WA) coastal communities. To improve community awareness and understanding of tsunami hazard and potential impact for Western Australia, the Fire and Emergency Services Authority of WA (FESA) established a collaborative partnership with GA in which science and emergency management expertise was applied to identified communities.

  • The development of climate change adaptation policies must be underpinned by a sound understanding of climate change risk. As part of the Hyogo Framework for Action, governments have agreed to incorporate climate change adaptation into the risk reduction process. This paper explores the nature of climate change risk assessment in the context of human assets and the built environment. More specifically, the paper's focus is on the role of spatial data which is fundamental to the analysis. The fundamental link in all of these examples is the National Exposure Information System (NEXIS) which has been developed as a national database of Australia's built infrastructure and associated demographic information. The first illustrations of the use of NEXIS are through post-disaster impact assessments of a recent flood and bushfire. While these specific events can not be said to be the result of climate change, flood and bushfire risks will certainly increase if rainfall or drought become more prevalent, as most climate change models indicate. The second example is from Australia's National Coastal Vulnerability Assessment which is addressing the impact of sea-level rise and increased storms on coastal communities on a national scale. This study required access to or the development of several other spatial databases covering coastal landforms, digital elevation models and tidal/storm surge. Together, these examples serve to illustrate the importance of spatial data to the assessment of climate change risk and, ultimately, to making informed, cost-effective decisions to adapt to climate change.

  • A review of the methods employed to collect 'buildings specific field data' following the impact of Tropical Cyclone Larry (March 2006) resulted in a plan to build a vehicular mounted rapid data inventory collection system to compliment post disaster surveys. The system assists to overcome issues related to restricted access, poor weather and difficult working conditions. The ability to quickly collect comprehensive information that is highly critical for both damage assessment and vulnerability model validation reduces assessment errors caused by rapid clearing of debris and repairs following the disaster, along with the use of tarpaulins which often obscure the level of damage viewed from the street. RICS consists of four 5-Megapixel Ethernet cameras attached to a tripod mounted on a vehicle, a GPS device and software written in C++. The images are compressed in jpeg format 'on-the-fly' and displayed in a Graphical User Interface (GUI) along with GPS location, bearing and speed. An additional display window shows the street-directory (UBD) roadmap and a GPS tracklog. Hot keys for instant damage assessment marking location and damage levels have been programed into the GUI. All images are geo-referenced and stored in a database.

  • Tropical cyclones, thunderstorms and sub-tropical storms can generate extreme winds that can cause significant economic loss. Severe wind is one of the major natural hazards in Australia. In this study, regional return period wind gust hazard (10 metre height over open terrain) is determined using a new methodology developed by Geoscience Australia over the past 3 years. The methodology developed for severe wind hazard (3-second peak gust) involves a combination of 3 models: - A Statistical Model (ie. data-based model) to quantify wind hazard using extreme value distributions. - A Monte Carlo method to calculate severe wind hazard produced by gust wind speeds using results from the Statistical Model. The method generates synthetic wind gust speeds by doing a numerical convolution of mean wind speeds and gust factors. - A high-resolution regional climate model (RCM) which produces gridded hourly 'maximum time-step mean- wind speed and direction fields. Area-averaged measurements from the RCM are 'corrected' for point measurement exposure by calibration with existing measurements. To assess model accuracy severe wind hazard return period levels (50, 100, 200, 500, 1000 and 2000 years) were determined for a number of locations where a long observation record is available. Comparisons are made between observational and RCM-generated return period of gust speeds; and also with the Australian/New Zealand wind loading standards (AS/NZS 1170.2, 2002).

  • Imagine you are an incident controller sitting in front of a computer screen that is showing you where a fire that's just started is likely to head. Not just that, but also what houses and other structures in the fire's path are likely to burn, and even the number and type of people living in the area - children, adults, elderly. In addition imagine that you can quantify the uncertainty in both the fire weather and also the state of the vegetation so as to deliver a range of simulations relating to the expected firespread which allow the incident controller to address 'what if' scenarios. Think of the advantages of such a program in making speedy, accurate decisions about where best to send fire trucks and fire-suppression aircraft; in being able to issue timely, locality-specific warning messages; in judging whether this fire will become so bad that it might warrant recommending not only an early, orderly evacuation of communities in its way, but also identifying the least risky roads for people to get to safety. A computer program that will not only be able to help with all this and more in a fire, but will also be capable of use at any time in identifying what structures, streets and communities would be at risk should a fire occur, enabling those at risk to undertake remedial work around their properties in advance to make them better fire-ready. This will be achieved by building up a library of possible / credible fire impact scenarios based on the knowledge of observed (historical) severe fire weather conditions as well as vegetation information (fuel type/amount/moisture).

  • The Rapid Inventory Collection System (RICS) is a vehicular data collection system (image and GPS) used for building/infrastructure damage and inventory assessment. The system consists of Ethernet cameras attached to a tripod mounted on a motor vehicle, a GPS receiver and software written in C++. The RICS data was used by the 2009 Victorian Bushfires Royal Commission for the impact assessment (field survey) which quantified the extent and severity of the damage caused by the fire-storm.

  • We develop globally applicable macroseismic Intensity Prediction Equations (IPEs) for earthquakes of moment magnitude MW 5.0 to 7.9 and intensities of degree II and greater for distances less than Rrup 300km. The IPEs are developed for two distance metrics: closest distance to rupture Rrup, and hypocentral distance, Rhyp. The key objective for developing the model based on hypocentral distance in addition to more rigorous and standard measure Rrup is to provide an IPE which can be used in near real-time earthquake response systems anywhere in the world, where information regarding the rupture dimensions of a fault may not be known in the immediate aftermath of the event. We observe that our models, particularly the model for the Rrup distance metric, generally have low median residuals with magnitude and distance. We provide distance-dependent intra-event uncertainties, in addition inter-event bias uncertainty. In particular, we address whether the direct use of IPEs lead to a reduction in overall uncertainties when compared to methods which use a combination of ground-motion prediction equations (GMPEs) and ground-motion to intensity conversion equations (GMICEs). Finally, we derive intensity-based site amplification factors given the predicted intensity and proxy estimates of near-surface shear-wave velocity. However, we find that these amplification factors lead to little, if any significant reduction of intensity residuals. This is in part due to the observation that the median site condition for intensity observations is approximately near the NEHRP site-class CD.

  • In order to calibrate earthquake loss models for the U.S. Geological Survey's Prompt Assessment of Global Earthquakes for Response (PAGER) system, two databases have been developed: an Atlas of ShakeMaps and a catalog of human population exposures to moderate to strong ground shaking (EXPO-CAT). The full ShakeMap Atlas currently contains over 5,600 earthquakes from January 1973 through December 2007, with almost 500 of these maps constrained by instrumental ground motions, macroseismic intensity data, community internet intensity observations, and published earthquake rupture models. The catalog of human exposures is derived using current PAGER methodologies. Exposure to discrete levels of shaking intensity is obtained by merging Atlas ShakeMaps with a global population database. Combining this population exposure dataset with historical earthquake loss data provides a useful resource for calibrating loss methodologies against a systematically-derived set of ShakeMap hazard outputs. Two applications of EXPO-CAT are illustrated: i) a simple objective ranking of country vulnerability to earthquakes, and; ii) the influence of time-of-day on earthquake mortality. In general, we observe that countries in similar geographic regions with similar construction practices tend to cluster spatially in terms of relative vulnerability. We find only limited quantitative evidence to suggest that time-of-day is a significant factor in earthquake mortality. Finally, we combine all the Atlas ShakeMaps to produce a global map of the peak ground acceleration (PGA) observed in the past 35 years, and compare this composite ShakeMap with existing global hazard models. In general, these analyses suggest that existing global and regional hazard maps tend to overestimate hazard.