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  • In plate boundary regions moderate to large earthquakes are often sufficiently frequent that robust estimates of fundamental seismic parameters such as the recurrence intervals of large earthquakes and maximum credible earthquake (Mmax) can be made. The same is not true for the Stable Continental Regions (SCRs) of the world. Large earthquakes are so infrequent that the data distributions upon which recurrence and Mmax estimates are based are heavily skewed towards magnitudes below Mw 5.0, and so require significant extrapolation up to magnitudes for which damaging ground-shaking might be expected. The rarity of validating evidence from palaeo-surface rupturing earthquakes limits the confidence with which extrapolated statistical parameters may be applied. Herein we present an earthquake catalogue containing, 150 palaeo-earthquakes, from 60 palaeo-earthquake features, based upon a >100 ka record of palaeo-earthquakes recorded in the Precambrian Shield of southwest Western Australia. From this data we show that Mmax for non-extended-SRC is well constrained at M7.22 and M7.65 for extended-SCR. In non-extended-SRC the earthquakes are likely episodic with periods of quiescence of 10-100ka in between active phases. The largest earthquakes are likely to occur on pre-existing faults. We expect these results might apply to most areas of non-extended-SCR worldwide.

  • One of the main outputs of the Earthquake Hazard project at Geoscience Australia is the national earthquake hazard map. The map is one of the key components of Australia's earthquake loading standard, AS1170.4. One of the important inputs to the map is the rate at which earthquakes occur in various parts of the continent. This is a function of the strain rate, or the rate of deformation, currently being experienced in different parts of Australia. This paper presents two contrasting methods of estimating the strain rate, and thus the seismicity, using the latest results from the seismology and geodynamic modelling programs within the project. The first method is based on a fairly traditional statistical analysis of an updated catalogue of Australian earthquakes. Strain rates, where measurable, were in the range of 10-16s-1 to around 10-18s-1 and were highly variable across the continent. By contrast, the second method uses a geodynamic numerical model of the Australian plate to determine its rate of deformation. This model predicted a somewhat more uniform strain rate of around 10-17s-1 across the continent. The uniformity of the true distribution of long term strain rate in Australia is likely to be somewhere between these two extremes but is probably of about this magnitude. In addition, this presentation will also give an overview of how this kind of work could be incorporated into future versions of the national earthquake hazard map in both the short and long term.

  • Natural hazards pose a serious threat to the lives and livelihoods of people living in developing countries throughout the Asia-Pacific region. One of the key mechanisms for reducing the impact of these events is to build capacity in these countries to mitigate for natural hazards. An improved understanding of natural hazards and the implementation of reliable, widely-tested computational models for assessing hazard will ultimately assist in disaster preparedness and response. Geoscience Australia (GA) in collaboration with the Australian Agency for International Development (AusAID) conducted a six day pre-IGC natural hazard modelling workshop for ASEAN and Pacific country delegates. The aim of the workshop was to improve their understanding of computational modelling techniques for volcanic ash, earthquake, tsunami and tropical cyclone hazards. The outcomes and lessons learnt will be discussed. Forty delegates from ASEAN and Pacific countries were invited to attend and receive training in one of four hazard modelling software programs relevant to the region: python-FALL3D (volcanic ash), ANUGA (tsunami), OpenQuake (earthquake) or TCRM (tropical cyclone). Relevance to their current employment area and the capacity to share the knowledge obtained through the training with colleagues were key criteria in selecting participants. Take home versions of the modelling software on USB stick and access to ongoing technical assistance from GA staff ensure that participants will be able to continue utilising the modelling software after the workshop. The knowledge gained will ultimately build the capacity of participants who have the responsibility of planning for potential natural hazards in their home countries.

  • Developed in consultation with Emergency Management Australia (EMA), this kit defines and maps major hazards affecting Australia - earthquakes, tsunamis, landslides, volcanoes, severe storms, cyclones, bushfires, floods and droughts. This kit helps students and teachers recognise risks from different natural hazards and the practical steps we can all take to reduce their effects. The Australian Natural Hazards Education Map Kit contains: - eight colour A3 poster maps with descriptive text - eight blackline A4 map masters - background information on each hazard - student activities - Emergency Management Australia hazard action cards Suitable for primary years 5-6 and secondary years 7-8.

  • The occurrence of the Indian Ocean Tsunami on 26 December, 2004 has raised concern about the difficulty in determining appropriate tsunami mitigation measures in Australia, due to the lack of information on the tsunami threat. A first step in the development of such measures is a tsunami hazard assessment, which gives an indication of which areas of coastline are most likely to experience tsunami, and how likely such events are. Here we present the results of a probabilistic tsunami hazard assessment for Western Australia (WA). Compared to other parts of Australia, the WA coastline experiences a relatively high frequency of tsunami occurrence. This hazard is due to earthquakes along the Sunda Arc, south of Indonesia. Our work shows that large earthquakes offshore of Java and Sumba are likely to be a greater threat to WA than those offshore of Sumatra or elsewhere in Indonesia. A magnitude 9 earthquake offshore of the Indonesian islands of Java or Sumba has the potential to significantly impact a large part of the West Australian coastline. The level of hazard varies along the coast, but is highest along the coast from Carnarvon to Dampier. Tsunami generated by other sources (e.g. large intra-plate events, volcanoes, landslides and asteroids) were not considered in this study, which limits our hazard assessment to recurrence times of 2000 years or less.

  • We have developed models for the prediction of bedrock ground motion response spectra in several regions of Australia. In Eastern Australia, we developed models for the Paleozoic Lachlan Fold Belt, and the Sydney Basin that lies within it, and in Western Australia we developed models for the Yilgarn Craton and the adjacent Perth Basin. The models are based on the broadband simulation of accelerograms using regional crustal velocity models and earthquake source scaling relations. For both the Lachlan Fold Belt and Yilgarn regions, we used comparison of synthetic seismograms with the recorded seismograms of small earthquakes to test and modify regional crustal velocity models. In Western Australia, we used the rupture models of the 1968 Mw 6.6 Meckering earthquake and the 1988 Mw 6.25, 6.4 and 6.5 Tennant Creek earthquakes to constrain the scaling relationship between seismic moment and rupture area. Other aspects of the source scaling relations were derived from our scaling relations for earthquakes in eastern North America (Somerville et al., 2001). In eastern Australia, the data available for historical earthquakes are insufficient to constrain earthquake scaling relations, so we have used the relations for Western Australia as well as the relations for the western United States (Somerville et al., 1999). We generated suites of broadband ground motion time histories using these source scaling relations and crustal structure models. These ground motion simulations were used to generate ground motion prediction models for each region. The ground motion models have been compared with the model of Liang et al. (2008) for Western Australia, with models for Eastern North America including Atkinson and Boore (2006), Somerville et al (2001), and Toro et al (1997), and with the NGA models.

  • The Joseph Bonaparte Gulf and Timor Sea region (JBG-TS) is an area of significance for multiple resource needs, from marine planning to offshore industry development. As such, information on seabed environments in this region is of interest to both industry and marine management. Geoscience Australia is focussed on the collation and preparation of regional pre-competitive environmental datasets, the outputs of which can be used for pre and post-bid environmental assessments and for emergency response planning. This report provides a spatial synthesis of seabed environments for the Joseph Bonaparte Gulf and Timor Sea region (JBG-TS) by identifying and describing significant habitats, communities, and potential geohazards. Data are sourced from existing literature, including publicly available industry data, as well as data collected from two seabed mapping surveys to the Van Diemen Rise in the eastern Timor Sea (GA-322 and GA-325).

  • This Australian volcanoes image set comprises 15 images on CD-ROM with accompanying descriptive text and student question/s for each image. Learn the history of Australia's hot spot volcanoes over 60 million years and examine 9 Australian volcanoes in detail. Suitable for primary levels Years 5-6 and secondary levels Years 7-10

  • Probabilistic seismic hazard analyses in Australia rely fundamentally on the assumption that earthquakes recorded in the past are indicative of where earthquakes will occur in the future. No attempt has yet been made to assess the potential contribution that data from active fault sources might make to the modelling process, despite successful incorporation of such data into United States and New Zealand hazard maps in recent years. In this paper we review the limited history of paleoseismological investigation in Australia and discuss the potential contribution of active fault source data towards improving our understanding of intraplate seismicity. The availability and suitability of Australian active fault source data for incorporation into future probabilistic hazard models is assessed, and appropriate methodologies for achieving this proposed.

  • Potential impacts of climate change present significant challenges for land use planning, emergency management and risk mitigation across Australia. Even in current climate conditions, the Rockhampton Regional Council area is subject to the impacts of natural hazards, such as bushfires, floods, and tropical cyclones (extreme winds and storm surge). All of these hazards may worsen with climate change. To consider future climate hazard within council practices, the Rockhampton Regional Council received funding from the National Climate Change Adaptation Research Grants Program Project for a project under the Settlements and Infrastructure theme. This funding was provided to evaluate the ability of urban planning principles and practices to accommodate climate change and the uncertainty of climate change impacts. Within this project, the Rockhampton Regional Council engaged Geoscience Australia to undertake the modelling of natural hazards under current and future climate conditions. Geoscience Australia's work, within the broader project, has utilised natural hazard modelling techniques to develop a series of spatial datasets describing hazards under current climate conditions and a future climate scenario. The following natural hazards were considered: tropical cyclone wind, bushfire, storm tide, coastal erosion and sea-level rise. Outputs of this project include a report, hazard maps and digital spatial data.