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  • <p>Geoscience Australia has recently released its 2018 National Seismic Hazard Assessment (NSHA18). Results from the NSHA18 indicate significantly lower seismic hazard across almost all Australian localities at the 1/500 annual exceedance probability level relative to the factors adopted for the current Australian Standard AS1170.4–2007 (R2018). These new hazard estimates, coupled with larger kp factors, have challenged notions of seismic hazard in Australia in terms of the recurrence of damaging ground motions. As a consequence, the new hazard estimates have raised questions over the appropriateness of the prescribed probability level used in the AS1170.4 to determine appropriate seismic demands for the design of ordinary-use structures. Therefore, it is suggested that the ground-motion exceedance probability used in the current AS1170.4 be reviewed in light of the recent hazard assessment and the expected performance of modern buildings for rarer ground motions. <p>Whilst adjusting the AS1170.4 exceedance probability level would be a major departure from previous earthquake loading standards, it would bring it into line with other international building codes in similar tectonic environments. Additionally, it would offer opportunities to further modernise how seismic demands are considered in Australian building design. In particular, the authors highlight the following additional opportunities: 1) the use of uniform hazard spectra to replace and simplify the spectral shape factors, which do not deliver uniform hazard across all natural periods; 2) updated site amplification factors to ensure continuity with modern ground-motion models, and; 3) the potential to define design ground motions in terms of uniform collapse risk rather than uniform hazard. Estimation of seismic hazard at any location is an uncertain science. However, as our knowledge improves, our estimates of the hazard will converge on the actual – but unknowable – (time independent) hazard. It is therefore prudent to regularly update the estimates of the seismic demands in our building codes using the best available evidence-based methods and models.

  • 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.

  • On 23 March 2012, at 09:25 GMT, a MW 5.4 earthquake occurred in the eastern Musgrave Ranges region of north-central South Australia, near the community of Ernabella (Pukatja). This was the largest earthquake to be recorded on mainland Australia for the past 15 years and resulted in the formation of a 1.6 km-long surface deformation zone comprising reverse fault scarps with a maximum vertical displacement of over 50 cm, and extensive ground cracking. Numerous small communities in this remote part of central Australia reported the tremor, but there were no reports of injury or significant damage. The maximum ground shaking is estimated to have been in the order of MMI VI. The earthquake occurred in Stable Continental Region (SCR) crust, over 1900 km from the nearest plate boundary. Fewer than fifteen historic earthquakes worldwide are documented to have produced coseismic surface deformation (i.e. faulting or folding) in the SCR setting. The record of surface deformation relating to the Ernabella earthquake therefore provides an important constraint on models relating surface rupture length to earthquake magnitude. Such models may be employed to better interpret Australia's rich prehistoric record of seismicity, thereby improving estimates of seismic hazard.

  • A compilation of short animations, describing the key processes involved in tsunami generation.

  • Understanding risk is a key tenet of the National Disaster Resilience Strategy and inherent to this is the discoverability, accessibility and availability of risk information. Access to this information is critical for land use or infrastructure planning decisions. Not only if this information required prior to the decision is made, but at some future date when investment is required to mitigate any created or residual risk. The community affected by these decisions also require the risk information so they can understand the hazard and risk and make decisions accordingly. Here, we showcase a suite of risk information developed by Geoscience Australia that can support land use and infrastructure planning decisions. GA officially adopted the Creative Commons 4.0 licence in 2009, recognising the investment made by the Australian Government in its development and the value it can serve to a range of stakeholders in government, industry, academia and the public. We contrast this with the case-study of the National Flood Risk Information Project where procurement practices of flood hazard and risk data have failed in delivering on the requirement of improving the community’s understanding of flood hazard and risk. We show how these challenges can be overcome so that ultimately decisions (for example in land use and infrastructure planning) can be made to minimise risk to the Australian community.

  • Indonesia is one of the most disaster prone countries in the world due to its hazard profile and high population exposure. Despite its risk profile, disaster management has not traditionally been informed by best available information. Since 2008, the Australian and Indonesian governments have partnered to increase the use of science and technology in Indonesia to support decision making in disaster management. Our partnership has concentrated on strengthening the evidence base for informed disaster management by improving: - hazard information for earthquake, tsunami, volcano and flood - spatial data for exposure (population, building, roads and infrastructure) - decision support tools such as InaSAFE that assist disaster managers to combine hazard and exposure data to inform disaster response and management. We have worked alongside technical and disaster management agencies, universities, non-government organisations and the private sector to develop Indonesian capacity to manage disasters and institutionalise best-practices. Partnerships have facilitated science-to-policy and science-to-programming outcomes in disaster management that help people prepare for, respond to and recover from crises. Ten years is a good time for a partnership to form, blossom and deliver effective and sustainable changes. The achievements over this time are too many to list in entirety. Science and Technology for Disaster Management merely scratches the surface to highlight the most significant achievements. There is a tendency in doing so to focus on achievements over the last three years. In most cases the achievements of this later period of the program have only been possible because they have built on and extended the achievements of the former seven years. Science and Technology for Disaster Management demonstrates how our collaboration has increased the use of science and technology in Indonesian disaster management by developing new knowledge and enhancing capacity, both within the scientists and within policy and decision makers. In doing so, tangible policies have been developed and implemented and practices have changed. The program has helped to strengthen relationships between agencies within Indonesia and also between Indonesia and Australia in the areas of disaster management and science more broadly. New relationships manifest as distinct government-to-government collaborations and strong peer-to-peer links.

  • The use of Interferometric Synthetic Aperture Radar (InSAR) to monitor volcano hazards by detecting ground deformation has been demonstrated in numerous cases around the world. This report presents an investigation of the feasibility of using InSAR as a broad scale volcano-monitoring tool in Papua New Guinea (PNG). This type of ongoing broad-scale monitoring would be a significant leap forward compared to the majority of past applications of InSAR for volcano monitoring, which have been sporadic and often conducted in hindsight. A major focus of this study was the development of open-source InSAR analysis software which makes it easier to implement in developing countries where resources may be limited. The environmental conditions of PNG, such as steep topography, dense vegetation and the moist, turbulent atmosphere pose significant challenges to volcano monitoring using InSAR. On the other hand, the remoteness of many of the volcanoes and the limited geophysical resources currently employed to monitor them, makes a broad-scale InSAR monitoring system an attractive proposition. The viability of InSAR as an ongoing tool for broad-scale volcano monitoring in PNG is constrained by the future availability of L-band Synthetic Aperture Radar (SAR) satellite imagery. The ALOS-2 mission should meet the data requirements of a broad-scale volcano monitoring programme. However, the present cost of ALOS data is prohibitive to ongoing monitoring, given the large volume of data required. The planned ALOS-2 mission will acquire SAR data with even higher temporal resolution, but this will be of little use to InSAR monitoring unless it is available at a cost conducive to regular access. At present, the greatest single barrier to a broad-scale InSAR monitoring system is the prohibitive cost of obtaining the required SAR imagery. To improve the accessibility of InSAR processing software to those in developing countries, the InSAR processing workflow that has been developed in this study is open source, being based on the GMTSAR package. In addition the interface has been simplified and a greater level of automation has been implemented to reduce the training required to become operational. The system has been designed to deal with the large volume of data processing required in a broad-scale volcano monitoring operation by parallelizing the most computationally intensive parts of the workflow. A case study of the Rabaul caldera demonstrates that L-band SAR interferometry can overcome many of the challenges of applying InSAR in PNG. However, continued development is required to enable time-series InSAR analysis. This would help to resolve the nonlinear nature of volcano deformation events and reduce the impact of spurious atmospheric delay signals. Commercial software is available to meet this requirement but the development of an open source alternative would be desirable to make the platform inclusive of developing countries.

  • This document presents a new set of earthquake hazard maps for consideration in the next revision of the earthquake loading code AS1170.4 "Structural design actions: Part 4 Earthquake actions in Australia". The earthquake catalogue used here includes events up until 2011. It is a combined version of several catalogues provided by external agencies. This represents the most complete catalogue of earthquakes compiled for Australia. The catalogue is more consistent through conversion of various magnitude measurements into a 'pseudo ML' scale. A systematic logic is used to select preferred magnitude types. Aftershocks, foreshocks and mine blasts have been identified and the declustered catalogue used here is cleaner than any previous Australian catalogue. Earthquake source zones applied in the hazard map use a unique combination of three different layers, which capture seismic characteristics at sub-national, regional and high-activity point scales. The map is one of the first in the world to apply a semi-quantitative measure of Mmax for majority of the source zones in the map. We apply recently developed ground motion prediction equations based on modern methods and data. These equations were used to calculate the ground motion at a range of response spectral accelerations, rather than just calculating the hazard for peak ground acceleration (PGA). A suite of maps is calculated using GA's Earthquake Risk Model (EQRM). The EQRM is open-source, allowing the results to be tested or modified independently. The final 2012 Australian earthquake hazard maps for a range of return periods and response spectral periods are presented herein.

  • This document is intended to provide a record of the participants, program, and discussions held at the Fire Weather and Risk Workshop, held at Peppers Craigieburn in Bowral, from 1st -4th September 2011. The workshop was attended by 77 delegates and was sponsored by the ACT Emergency Services Agency, Geoscience Australia, the Bureau of Meteorology, and the Federal Attorney Generals Department. These proceedings include the: - workshop program - executive summary by the workshop organizers - presentation abstracts (optional) - summaries of presentations and discussions (compiled at the workshop by the session chairs and scribes) - survey of participants- expectations of the workshop (received prior to the workshop) - results of a post-workshop evaluation - list of participants. This document also includes an invited journalistic-styled article by science journalist, Nick Goldie (Senior Deputy Captain, Colinton Rural Fire Brigade, NSW RFS) which provided an independent view on the activities that occurred over the three days.

  • A community Safety Capbility Flyer was produced to showcase the work undertaken in the Community Safety Value Stream. The flyer includes an introduction to the Community Safety Value Stream, case studies of the work Geoscience Australia does in this space and information on how to engage with Geoscience Australia via the products, tools, models and applications that are produced. This flyer is intended for use a conferences and where promotional material would beneficial to showcase the work undertaken at Geoscience Australia such as the Floodplain Management Association Conference on 19-22 May 2015.