From 1 - 10 / 217
  • 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.

  • System will not accept abstract. See TRIM link: D2011-143376

  • Natural disasters are a frequent occurrence in the Asia-Pacific region because of the combination of very dense population and very hazard-prone areas. Australia has recently been called upon to play a leadership role in responding to natural disasters, especially in recent years, with earthquakes in Pakistan and Indonesia, landslides in the Philippines, tsunami events in Indonesia and the Solomon Islands, cyclone related flooding in Papua New Guinea, and the regular occurrence of cyclones in the southwest Pacific and southeast Asia. Furthermore, there is an increasing trend in the number and size of disasters as the effects of climate change are felt and as rapid population growth and urbanisation results in increasingly large and vulnerable populations in areas exposed to natural hazards. An activity undertaken by Geoscience Australia (GA) for AusAID made a preliminary assessment of natural hazard risk across all Asia-Pacific countries. The objective was to gain a better understanding of disaster risks across the AusAID portfolio and support AusAID to better target disaster risk reduction and humanitarian response activities. This project sought to broadly identify the characteristics, frequency, location and potential consequences of rapid-onset natural hazards, including: earthquake, tsunami, landslide, flood, cyclone, flood, wildfire and volcanic eruptions. Subsequently GA has partnered with AusAID to implement programs in the Asia-Pacific region aimed at building the capacity Government agencies to assess natural hazard risk.

  • The role of neotectonism in the recent landscape evolution of the Eastern Blue Mountains, NSW Dan Clark, Andrew McPherson and Kerrie Tomkins Faults of the Lapstone Structural Complex (LSC) underlie 100 km, and perhaps as much as 160 km, of the eastern range front of the Blue Mountains, west of Sydney. More than a dozen major faults and monoclinal flexures have been mapped along its extent. The Lapstone Monocline is the most prominent of the flexures, and accounts for more than three quarters of the deformation across the complex at its northern end. Opinion varies as to whether recent tectonism, erosional exhumation of a pre-existing structure, or a combination of both, best accounts for the deeply dissected Blue Mountains plateau that we see today. We present results from an ongoing investigation of Mountain Lagoon, a small fault-bound basin bordering the Kurrajong Fault in the northern part of the LSC. Drilling has identified 15 m of fluvial, colluvial and lacustrine sediments overlying shale bedrock trapped behind a sandstone fault barrier corresponding to the Kurrajong Fault. Dating of pollen grains preserved in the basal sediments overlying shale suggest that the fault angle depression began trapping sediment in the Early to Middle Miocene. Strongly heated Permo-Triassic gymnosperm pollen in the same strata provides circumstantial evidence that sediment accumulation postdates the emplacement of basalts at Green Scrub at ca. 18.8 Ma. Our results indicate that only 15 m of the 130 m of throw across the Kurrajong Fault is Neogene in age. From this it may be deduced that erosional exhumation is the dominant process responsible for formation of the deeply dissected Blue Mountains landscape. However, it is also possible to demonstrate the influence of ongoing tectonism on stream channel over-steepening, knick point initiation, and the continuing dissection of the plateau.

  • This paper discusses two of the key inputs used to produce the draft National Earthquake Hazard Map for Australia: 1) the earthquake catalogue and 2) the ground-motion prediction equations (GMPEs). The composite catalogue used draws upon information from three key catalogues for Australian and regional earthquakes; a catalogue of Australian earthquakes provided by Gary Gibson, Geoscience Australia's QUAKES, and the International Seismological Centre. A complex logic is then applied to select preferred location and magnitude of earthquakes depending on spatial and temporal criteria. Because disparate local magnitude equations were used through time, we performed first order magnitude corrections to standardise magnitude estimates to be consistent with the attenuation of contemporary local magnitude ML formulae. Whilst most earthquake magnitudes do not change significantly, our methodology can result in reductions of up to one local magnitude unit in certain cases. Subsequent ML-MW (moment magnitude) corrections were applied. The catalogue was declustered using a magnitude dependent spatio-temporal filter. Previously identified blasts were removed and a time-of-day filter was developed to further deblast the catalogue.

  • Decision making on community, government and business vulnerability and risk requires a reliable understanding of the nature of the assets at risk. These include people, buildings, economic activity and critical infrastructure. Collectively they are termed 'exposure' and Geoscience Australia (GA) has developed a system which now defines a wide range of exposure types in a current and consistent way on a national scale. The capability is called the National Exposure Information System and is now widely known by the acronym NEXIS. This investment was prompted initially by the agency's own information needs, but more recently development resources have been supplemented with contributions made by other stakeholders to meet their information needs.

  • Probabilistic seismic hazard assessment (PSHA) is an important tool for reducing earthquake fatalities through land use planning, emergency management training based on credible earthquake scenarios, and improved building codes. The application of PSHA in Indonesia has seen rapid developmetn in the last few years, with development of a PSHA for Sumatra by Petersen et al. (2004), followed by PSHA of Java and Sumatra by Irsyam et al. (2008) and the most recent all-Indonesia PSHA developed by a group of Indonesian scientists known as "Team-9". These recent PSHA's for Indonesia show a generally increasing level of earthquake hazard, with the increase mainly associated with the new information avaialble on the earthquake activity of crustal faults, and, too a lesser extent, on intraslab earthquake activity. As part of a project to strengthen the Government of Indonesia's capacity to produce better PSHA's, we have used some of teh most recent information availble on earthquake activity and site response in the Indonesia province of Central Java. Our PSHA is implemented using an event-based approach to the calculation of seismic hazard, and it relised on geologic information on the slip rates of active crustal faults to define earthquake sources, and also on topography and surface geology informaiton to estimate site amplification. We will discuss our results in the context of extending its application to all of Indonesia.

  • This education resource comprises earthquake images with background information and descriptions of each image - includes world plate boundaries and earthquake distribution, distribution of earthquakes in Australia and examples of earthquake events, Australia's Seismological Network that is managed by Geoscience Australia, how earthquakes are measured, a case study of Tennant Creek and a map indicating Australia's earthquake hazard. Suitable for primary level Years 5-6 and secondary level Years 7-12.