From 1 - 10 / 139
  • Public concerns have been raised about the potential for induced seismicity as state and territory governments lift moratoriums on hydraulic stimulation activities for the exploration and extraction of unconventional hydrocarbons. The Scientific Inquiry into Hydraulic Fracturing in the Northern Territory articulated the need for a traffic-light system “to minimise the risk of occurrence of seismic events during hydraulic fracturing operations” within the Beetaloo Sub-basin. A temporary seismic network (Phase 1) was deployed in late 2019 to monitor baseline seismic activity in the basin. Based on the data analysed herein (November 2019 – April 2021), no seismic events were identified within the area of interest suggesting that the Beetaloo Sub-basin is largely aseismic. Observations to date indicate that there is potential to identify events smaller than ML=1.5 within the basin. The recent installation of ten semi-permanent stations for continuous real-time monitoring will contribute to ongoing baseline monitoring efforts and support the implementation of an induced seismicity traffic-light system. The outcome of this study will be used to build knowledge about potential human-induced seismic activity in the region that may be associated with unconventional hydrocarbon recovery. This paper was presented at the Australian Earthquake Engineering Society 2021 Virtual Conference, Nov 25 – 26.

  • Four of Australia's largest five population centres are topographically constrained by prominent escarpments (i.e. Sydney, Melbourne, Perth, Adelaide). These escarpments are underlain by faults or fault complexes capable of hosting damaging earthquakes. Paleoseismological investigations over the last decade indicate that the seismogenic character (e.g. recurrence and magnitude) of these structures varies markedly. Uplift rates on range bounding faults in the Mount Lofty Ranges suggest average recurrence times on individual faults for Mmax earthquakes (MW 7.1-7.4) in the order of 10-20 ka. A high density of faults with demonstrated Late Quaternary surface rupture occurring proximally to Adelaide suggests recurrence times for damaging ground shaking at a given location from earthquakes on these faults in the hundreds to low thousands of years. Uplift rates on faults proximal to Melbourne (and the Latrobe Valley, where much of Melbourne's power is generated) in some cases exceed those of the Mount Lofty Ranges. However, a lower relative density of seismogenic faults proximal to the conurbation of Melbourne is suggestive of a lesser hazard than for Adelaide. In contrast to Melbourne and Adelaide, paleoseismological investigations on the Darling Fault near Perth, and the Lapstone Structural Complex near Sydney, indicate average recurrence for Mmax events in the hundreds of thousands to millions of years. Of course, distal larger events and proximal sub-Mmax events have been demonstrated to be damaging in these areas (e.g. 1968 Ms6.8 Meckering, 1989 ML5.6 Newcastle). The same is true for Adelaide and Melbourne (e.g. 1954 ML5.4 Adelaide, 2012 ML 5.4 Moe). Further research is required to demonstrate that earthquakes of sub-morphogenic and morphogenic magnitude might be modelled on the same Guttenberg-Richter distribution curve.

  • Tropical cyclones are the most common disaster in the Pacific, and among the most destructive. In December 2012, Cyclone Evan caused over US$200 million damage in Samoa, nearly 30 percent of Samoan GDP. Niue suffered losses of US$85 million following Cyclone Heta in 2004-over five times its GDP. As recently as January 2014, Cyclone Ian caused significant damage throughout Tonga, resulting in the first payout of the Pacific Catastrophe Risk Insurance Pilot system operated by the World Bank (2014). According to the Intergovernmental Panel on Climate Change (IPCC), intense tropical cyclone activity in the Pacific basin will likely increase in the future (IPCC 2013). But such general statements about global tropical cyclone activity provide little guidance on how impacts may change locally or even regionally, and thus do little to help communities and nations prepare appropriate adaptation measures. This study assesses climate change in terms of impact on the human population and its assets, expressed in terms of financial loss. An impact focus is relevant to adaptation because changes in hazard do not necessarily result in a proportional change in impact. This is because impacts are driven by exposure and vulnerability as well as by hazard. For example, a small shift in hazard in a densely populated area may have more significant consequences than a bigger change in an unpopulated area. Analogously, a dense population that has a low vulnerability to a particular hazard might not need to adapt significantly to a change in hazard. Even in regions with high tropical cyclone risk and correspondingly stringent building codes, such as the state of Florida, a modest 1 percent increase in wind speeds can result in a 5 percent to 10 percent increase in loss to residential property. Quantifying the change impact thus supports evidence-based decision making on adaptation to future climate risk.

  • Tsunami hazard modelling for Tonga shows the potential impacts of tsunami generated by a very large earthquake on the nearby Tongan Trench.

  • 40 years atmospheric reanalysis for Australia region. http://www.ecmwf.int/products/data/archive/descriptions/e4/index.html

  • The datasets created to produce the emergency mapping support products which contributed to fulfilling GA's arrangements in supporting the outcomes sought by the Australian Government during disaster events.

  • Tsunamis pose considerable risk to coastal communities around the globe and understanding this risk is a key aspect of emergency management and risk reduction. This paper explores the nature and extent of tsunami hazard to NSW coastal communities and informs tsunami emergency planning and management. We outline the results of recent risk scoping which have examined sources of tsunami hazard, and tsunami history together with results of inundation studies for selected sites and discuss the level of tsunami risk to these NSW communities. We also outline how the results have complimented research by the Australian Bureau of Meteorology in confirming tsunami warning thresholds for NSW. Work undertaken to date indicates the coast of NSW has a moderate tsunami hazard level. Whilst historical impact of tsunami inundation in NSW has been relatively minor, and generally restricted to marine based events, the modelling of selected earthquake generated events indicates the potential for land inundation particularly at high (rare) return periods. Low lying populated communities around estuary foreshores are particularly at risk although results also indicate the potential for inundation of open coast sites at very high (very rare) return periods. The results confirm the need for and support the ongoing collaborative development of emergency management arrangements for tsunami.

  • During the last five years, the Australian aid program has supported a series of successful capacity-building activities for natural disaster risk assessment within neighboring Southeast Asian countries. Although the modality of engagement between the agencies has varied in each country context, the successes have been uniformly underpinned by strong, long-term bilateral government-to-government (G2G) relationships between Geoscience Australia (GA) and partner technical agencies.

  • The disasters caused by tsunamis the last 10 years have highlighted the need for a thorough understanding of the global and regional tsunami hazard and risk. At present, the 2004 and 2011 tsunamis hint that their induced risk are dominated by large infrequent events with possibly long return periods. However, an in-depth understanding of how individual contributions from sources of different strength and frequency govern the hazard and risk is presently not clear. A first global analysis of tsunami hazard using earthquake sources was conducted in 2008 on behalf of the UN-ISDR Global Assessment Report (GAR). Recently, this initiative has resulted in the first, fully probabilistic global tsunami hazard assessment. Economic loss calculations based on building fragility curves largely derived from recent major tsunamis have also been included to assess the risk. Still, this complex assessment is premature. Further efforts are needed, requiring joint expertise covering a wide range of topics such as the understanding of sources, hydrodynamics, probability and statistics, as well as vulnerability and exposure. Therefore, there is a dire need for a joint interdisciplinary effort delivering data and tools that may help decision makers in assessing their tsunami hazard and risk. To this end, we propose to establish a Global Tsunami Model (GTM) that will emphasize tsunami hazard and risk analysis on a global scale. The GTM will be based on the initial work in GAR, but should eventually involve a broader community. The motivation, the needs, and the possible contributors for such a GTM will be discussed.

  • Seismic hazard models, commonly produced through probabilistic seismic hazard analysis, are used to establish earthquake loading requirements for the built environment. However, there is considerable uncertainty in developing seismic hazard models, which require assumptions on seismicity rates and ground-motion models (GMMs) based on the best evidence available to hazard analysts. This paper explores several area-based tests of long-term seismic hazard forecasts for the Australian continent. ShakeMaps are calculated for all earthquakes of MW 4.25 and greater within approximately 200 km of the Australian coastline using the observed seismicity in the past 50 years (1970-2019). A “composite ShakeMap” is generated that extracts the maximum peak ground acceleration “observed” in this 50-year period for any site within the continent. The fractional exceedance area of this composite map is compared with four generations of Australian seismic hazard maps for a 10% probability of exceedance in 50 years (~1/500 annual exceedance probability) developed since 1990. In general, all these seismic hazard models appear to be conservative relative to the observed ground motions that are estimated to have occurred in the last 50 years. To explore aspects of possible prejudice in this study, the variability in ground-motion exceedance was explored using the Next Generation Attenuation-East GMMs developed for the central and eastern United States. The sensitivity of these results is also tested with the interjection of a rare scenario earthquake with an expected regional recurrence of approximately 5,000 - 10,000 years. While these analyses do not provide a robust assessment of the performance of the candidate seismic hazard for any given location, they do provide—to the first order—a guide to the performance of the respective maps at a continental scale. This paper was presented at the Australian Earthquake Engineering Society 2021 Virtual Conference, Nov 25 – 26.