hazards
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Tropical Cyclone (TC) Yasi crossed Queensland's Cassowary Coast during the night of the 2nd and 3rd of February, 2011. The cyclone was forecast by BoM (2011) to be a severe storm with wind gusts forecast to exceed the design gust wind speeds for houses set out in AS4055. Following the passage of the cyclone, it was evident that the severe wind and large coastal storm surge had caused significant damage to the region's building stock. Geoscience Australia (GA), together with collaborators from the National Institute of Water and Atmospheric Research, New Zealand (NIWA), Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) and Maddocks & Associates, undertook a survey of damage to the region's buildings caused by severe wind and storm surge.
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Geoscience Australia is currently drafting a new National Earthquake Hazard Map of Australia using modern methods and models. Among other applications, the map is a key component of Australia's earthquake loading code AS1170.4. In this paper we provide a brief history of national earthquake hazard maps in Australia, with a focus on the map used in AS1170.4, and provide an overview of the proposed changes for the new map. The revision takes advantage of the significant improvements in both the data sets and models used for earthquake hazard assessment in Australia since the original maps were produced. These include: - An additional 20+ years of earthquake observations - Improved methods of declustering earthquake catalogues and calculating earthquake recurrence - Ground motion prediction equations (i.e. attenuation equations) based on observed strong motions instead of intensity - Revised earthquake source zones - Improved maximum magnitude earthquake estimates based on palaeoseismology - The use of open source software for undertaking probabilistic seismic hazard assessment which promotes testability and repeatability The following papers in this session will address in more detail the changes to the earthquake catalogue, earthquake recurrence and ground motion prediction equations proposed for use in the draft map. The draft hazard maps themselves are presented in the final paper.
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Manila is one of the world's megacities, and the Greater Metro Manila Area is prone to natural disasters. These events may have devestating consequences for individuals, communities, buildings, infrastructure and economic development. Understanding the risk is essential for implementing Disaster Risk Reduction programs. In partnership with AusAID, Geoscience Australia is providing technical leadership for risk analysis projects in the Asia-Pacific Region. In the Philippines, Geoscience Australia is engaging with Government of the Philippines agencies to deliver the "Enhancing Risk Analysis Capacities for Flood, Tropical Cyclone Severe Wind and Earthquake in the Greater Metro Manila Area" Project.
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Geoscience Australia is currently drafting a new National Earthquake Hazard Map of Australia using modern methods and models. Among other applications, the map is a key component of Australia's earthquake loading code AS1170.4. In this paper we provide a brief history of national earthquake hazard maps in Australia, with a focus on the map used in AS1170.4, and provide an overview of the proposed changes for the new map. The revision takes advantage of the significant improvements in both the data sets and models used for earthquake hazard assessment in Australia since the original maps were produced. These include: - An additional 20+ years of earthquake observations - Improved methods of declustering earthquake catalogues and calculating earthquake recurrence - Ground motion prediction equations (i.e. attenuation equations) based on observed strong motions instead of intensity - Revised earthquake source zones - Improved maximum magnitude earthquake estimates based on palaeoseismology - The use of open source software for undertaking probabilistic seismic hazard assessment which promotes testability and repeatability The following papers in this session will address in more detail the changes to the earthquake catalogue, earthquake recurrence and ground motion prediction equations proposed for use in the draft map. The draft hazard maps themselves are presented in the final paper.
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Interactive Maps is a discovery and exploration view of Geoscience Australia's geospatial services. The following scientific and decision support themes have curated content comprised of maps and functions. Each map has queries and functions with linked access to OGC (Open Geospatial Consortium) web services and metadata. This system replaces MapConnect and AMSIS applications.
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Stochastic finite-fault ground-motion prediction equations (GMPEs) are developed for the stable continental region of southeastern Australia (SEA). The models are based on reinterpreted source and attenuation parameters for small-to-moderate magnitude local earthquakes and a dataset augmented with ground-motion records from recent significant earthquakes. The models are applicable to horizontal-component ground-motions for earthquakes 4.0 <= MW <= 7.5 and at distances less than 400 km. The models are calibrated with updated source and attenuation parameters derived from SEA ground-motion data. Careful analysis of well-constrained earthquake stress parameters indicates a dependence on hypocentral depth. It is speculated that this is the effect of an increasing crustal stress profile with depth. However, rather than a continuous increase, the change in stress parameter appears to indicate a discrete step near 10 km depth. Average stress parameters for SEA earthquakes shallower and deeper than 10 km are estimated to be 23 MPa and 50 MPa, respectively. These stress parameters are consequently input into the stochastic ground-motion simulations for the development of two discrete GMPEs for shallow and deep events. The GMPEs developed estimate response spectral accelerations comparable to the Atkinson and Boore (2006) GMPE for eastern North America (ENA) at short rupture distances (less than approximately 100 km). However, owing to higher attenuation observed in the SEA crust (Allen and Atkinson, 2007), the SEA GMPEs estimate lower ground-motions than ENA models at larger distances. A correlation between measured VS30 and ?0 was developed from the limited data available to determine the average site condition to which the GMPEs are applicable. Assuming the correlation holds, a VS30 of approximately 820 m/s is obtained assuming an average path-independent diminution term ?0 of 0.006 s from SEA seismic stations. Consequently, the GMPE presented herein can be assumed to be appropriate for rock sites of B to BC site class in the National Earthquake Hazards Reduction Program (NEHRP, 2003) site classification scheme. The response spectral models are validated against moderate-magnitude (4.0 <= MW <= 5.3) earthquakes from eastern Australia. Overall the SEA GMPEs show low median residuals across the full range of period and distance. In contrast, ENA models tend to overestimate response spectra at larger distances. Because of these differences, the present analysis justifies the need to develop Australian-specific GMPEs where ground-motion hazard from a distant seismic source may become important.
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The Philippine Institute of Volcanology and Seismology (PHIVOLCS) and Geoscience Australia (GA) have developed a long-term partnership in order to better understand and reduce the risks associated with earthquake hazards in the Philippines. The Project discussed herein was supported by the Australian Agency for International Development (AusAID). Specifically, this partnership was designed to enhance the exposure and damage estimation capabilities of the Rapid Earthquake Damage Assessment System (REDAS), which has been designed and built by PHIVOLCS. Prior to the commencement of this Project, REDAS had the capability to model a range of potential earthquake hazards including ground shaking, tsunami inundation, liquefaction and landslides, as well as providing information about elements at risk (e.g., schools, bridges, etc.) from the aforementioned hazards. The current Project enhances the exposure and vulnerability modules in REDAS and enable it to estimate building damage and fatalities resulting from scenario earthquakes, and to provide critical information to first-responders on the likely impacts of an earthquake in near real-time. To investigate this emergent capability within PHIVOLCS, we have chosen the pilot community of Iloilo City, Western Visayas. A large component of this project has been the compilation of datasets to develop building exposure models, and subsequently, developing methodologies to make these datasets useful for natural hazard impact assessments. Collection of the exposure data was undertaken at two levels: national and local. The national exposure dataset was gathered from the Philippines National Statistics Office (NSO) and comprises basic information on wall type, roof type, and floor area for residential buildings. The NSO census dataset also comprises crucial information on the population distribution throughout the Philippines. The local exposure dataset gathered from the Iloilo City Assessors Office includes slightly more detailed information on the building type for all buildings (residential, commercial, government, etc.) and appears to provide more accurate information on the floor area. However, the local Iloilo City dataset does not provide any information on the number of people that occupy these buildings. Consequently, in order for the local data to be useful for our purposes, we must merge the population data from the NSO with the local Assessors Office data. Subsequent validation if the Iloilo City exposure database has been conducted through targeted foot-based building inventory surveys and has allowed us to generate statistical models to approximate the distribution of engineering structural systems aggregated at a barangay level using simple wall and roof-type information from the NSO census data. We present a comparison of the national and local exposure data and discuss how information assembled from the Iloilo City pilot study - and future study areas where detailed exposure assessments are conducted - could be extended to describe the distribution of building stock in other regions of the Philippines using only the first-order national-scale NSO data. We present exposure information gathered for Iloilo City at barangay level in a format that can be readily imported to REDAS for estimating earthquake impact.
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Coastal communities in Australia are particularly exposed to disasters resulting from the coincidence of severe wind damage, storm surge, coastal flooding and shoreline erosion during cyclones and extra-tropical storms. Because the climatic drivers of these events are stronger during or across specific years (e.g. during La Nina periods), they can repeatedly impact the coast over periods of weeks, months or up to a few years. The consequences of individual events are therefore exacerbated with little or no opportunity for recovery of natural systems or communities. This poster summarises the objectives, approach and methodology for this storm surge project. A contribution to the Bushfire and Natural Hazards CRC.
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The Greater Metro Manila Area is one of the world's megacities and is home to about 12 million people. It is located in a region at risk from earthquakes, volcanic eruptions, tropical cyclones, riverine flooding, landslides and other natural hazards. Major flooding affected the Greater Metro Manila Area in September 2009 following the passage of Typhoon Ketsana (known locally as Typhoon Ondoy). Following this event, the Australian Aid Program supported Geoscience Australia to undertake a capacity building project with its partner agencies in the Government of the Philippines. The output of this project has been a series of risk information products developed by agencies in the Collective Strengthening of Community Awareness for Natural Disasters (CSCAND) group. These products quantify the expected physical damage and economic loss to buildings caused by earthquakes, tropical cyclone severe wind and riverine flooding across the Greater Metro Manila Area. Spatial data is a key input to the development of hazard models and information on exposure, or the 'elements at risk'. The development of a spatially enabled exposure database was a crucial element in the construction of risk information products for the Greater Metro Manila Area. The database provides one central repository to host consistent information about the location, size, type, age, residential population and structural characteristics of buildings within the area of interest. Unique spatial analysis techniques were employed to quantify and record important aspects of the built environment, for inclusion in the database. The process of exposure data development within the Greater Metro Manila Area, including a new application developed by Geoscience Australia for estimating the geometric characteristics of buildings from high resolution elevation data and multi-spectral imagery, will be presented.
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A compilation of short animations, describing the key processes involved in tsunami generation.