In 2017 Queensland Fire and Emergency Services (QFES) completed the State Natural Hazard Risk Assessment which evaluated the risks presented by seven in-scope natural hazards. The risks presented by earthquakes were evaluated as part of this assessment in broad terms. The assessment highlighted a number of key vulnerabilities and risks presented by earthquakes to the communities of Queensland requiring further analysis. As QFES matures the Queensland Emergency Risk Management Framework (QERMF) by working with Local and District Disaster Management Groups (LDMGs/DDMGs), opportunities have arisen whereby QFES, in collaboration with relevant Federal and State Government and industry partners, are in a position to provide State-level support to LDMGs and DDMGs, through the development of in-depth risk assessments. The State Natural Hazard Risk Assessment 2017 and the State Disaster Management Plan 2018 note that the QERMF, as the endorsed methodology for the assessment of disaster related risk, is intended to: • Provide consistent guidance in understanding disaster risk that acts as a conduit for publicly available risk information. This approach assists in establishing and implementing a framework for collaboration and sharing of information in disaster risk management, including risk informed disaster risk reduction strategies and plans. • Encourage holistic risk assessments that provide an understanding of the many different dimensions of disaster risk (hazards, exposures, vulnerabilities, capability and capacities). The assessments include diverse types of direct and indirect impacts of disaster, such as physical, social, economic, environmental and institutional. The assessment and its intended audience This risk assessment was developed using the QERMF to undertake a scenario-based analysis of Queensland’s earthquake risk. It is intended to complement and support LDMGs and DDMGs in the completion of their risk-based disaster management plans. The development of the State Earthquake Risk Assessment 2018 was supported by Geoscience Australia (GA) through the provision of expert advice, relevant spatial datasets and the development of the scenarios used through this assessment. Input has been sought from GA to help contextualise the findings of the National Seismic Hazard Assessment 2018 for Queensland. Consultation with the University of Queensland has been sought to provide the ‘Queensland Context’, capitalising on the 80-year history of earthquake research and study undertaken by the university. A robust scientific basis enhances the assessment and enables disaster management groups to inform their local level planning. Overall, the assessment and associated report seeks to complement and build upon existing Local and District earthquake risk assessments by providing updated and validated information relating to the changes in understanding Queensland’s earthquake potential.

This poster presents a summary of discussion topics following the 2018 Lake Muir, WA, Earthquake Sequence Community Engagement Workshop held in Frankland River, WA, on 28 November 2018

This paper explores the implementation of the Natural Resources Canada’s 5th Generation national seismic hazard model as developed for the National Building Code of Canada (NBCC), within the OpenQuake-engine. It also describes the reconciliation of the differences in hazard estimates relative to the published NBCC values, calculated using GSCFRISK. Source and ground-motion input models developed for the GSCFRISK software were translated to the OpenQuake-engine format for the hazard comparison. In order to successfully undertake this process, several adjustments to the OpenQuake code were needed to mimic the behavior of GSCFRISK. This required the development of new functions for earthquake rupture scaling and ground-motion interpolation. Hazard values estimated using the OpenQuake-engine are generally in good agreement with the 2015 NBCC national-scale hazard values, with differences less than 2-3% typically achieved. Where larger differences arise, they can be rationalized in terms of differences between the behaviours of the two software engines with respect to earthquake rupture length uncertainty and maximum ground-motion integration distance.

On the 4th September 2010 at 4:35am a magnitude 7.1 earthquake occurred near Darfield in Canterbury, New Zealand. The associated fault ruptured towards Christchurch, which is New Zealand’s second largest city, and haswith a population of 350,000 people. The ground shaking was severe and critical infrastructure suffered widespread damage. The earthquake represented the most damaging earthquake event since the 3rd Feb 1931 Napier earthquake and has provided and excellent opportunity to gain a better understanding of New Zealand infrastructure vulnerability. The similarity of older legacy assets in Christchurch to those in Australia, many of which haves been retrofitted, has made this event of interest to Australia as well.

Seismic risk assessment involves the development of fragility functions to express the relationship between ground motion intensity and damage potential. In evaluating the risk associated with the building inventory in a region, it is essential to capture ‘actual’ characteristics of the buildings and group them so that ‘generic building types’ can be generated for further analysis of their damage potential. Variations in building characteristics across regions/countries largely influence the resulting fragility functions, such that building models are unsuitable to be adopted for risk assessment in any other region where a different set of building is present. In this paper, for a given building type (represented in terms of height and structural system), typical New Zealand and US building models are considered to illustrate the differences in structural model parameters and their effects on resulting fragility functions for a set of main-shocks and aftershocks. From this study, the general conclusion is that the methodology and assumptions used to derive basic capacity curve parameters have a considerable influence on fragility curves.

The geological structure of southwest Australia comprises a rich, complex record of Precambrian cratonization and Phanerozoic continental breakup. Despite the stable continental cratonic geologic history, over the past five decades the southwest of Western Australia has been the most seismically active region in continental Australia though the reason for this activity is not yet well understood. The Southwest Australia Seismic Network (SWAN) is a temporary broadband network of 27 stations that was designed to both record local earthquakes for seismic hazard applications and provide the opportunity to dramatically improve the rendering of 3-D seismic structure in the crust and mantle lithosphere. Such seismic data are essential for better characterization of the location, depth and attenuation of the regional earthquakes, and hence understanding of earthquake hazard. During the deployment of these 27 broadband instruments, a significant earthquake swarm occurred that included three earthquakes with local magnitude (MLa) ≥ 4.0, and the network was supplemented by an additional six short-term nodal seismometers at 10 separate sites in early 2022, as a rapid deployment to monitor this swarm activity. The SWAN experiment has been continuously recording since late 2020 and will continue into 2023. These data are archived at the FDSN recognized Australian Passive Seismic (AusPass) Data center under network code 2P and will be publicly available in 2025. <b>Citation:</b> Meghan S. Miller, Robert Pickle, Ruth Murdie, Huaiyu Yuan, Trevor I. Allen, Klaus Gessner, Brain L. N. Kennett, Justin Whitney; Southwest Australia Seismic Network (SWAN): Recording Earthquakes in Australia’s Most Active Seismic Zone. <i>Seismological Research Letters </i><b>2023</b>;; 94 (2A): 999–1011. doi: https://doi.org/10.1785/0220220323

<p>The 2018 Australian Probabilistic Tsunami Hazard Assessment (PTHA18) was developed by Geoscience Australia to better understand Australia’s tsunami hazard due to earthquakes in the Pacific and Indian Oceans. The PTHA18 contains over a million hypothetical earthquake-tsunami scenarios, with associated return periods which are constrained using historical earthquake data and long-term plate tectonic motions. The tsunami propagation is modelled globally for 36 hours, and results are stored at thousands of sites in deep waters offshore of Australia. Average Return Interval (ARI) estimates are also provided, along with a representation of the associated uncertainties. ARI uncertainties tend to be large because of fundamental limitations in current scientific knowledge regarding the frequency of large earthquakes on global subduction zones. <p>The PTHA18 provides a nationally consistent basis for earthquake-tsunami scenario design, as required for inundation hazard assessments. The results and source-code are also freely available. The current paper aims to provide a short and accessible introduction to the PTHA18 methodology and results, while deliberately limiting technical details which are covered extensively in the associated technical report and code repository.

Seismicity in the intraplate southwest of Western Australia is poorly understood, despite evidence for potentially damaging earthquakes of magnitude>M6. Identifying stress-focusing geological structures near significant earthquake sequences assists in understanding why these earthquakes occur in seemingly random locations across a region of more than 250 000 km2. On 16 September 2018, an ML5.7 earthquake occurred near Lake Muir in the southwest of Western Australia and was followed by an ML5.4 aftershock. The main earthquake formed a mainly northtrending fault scarp ~5 km in length and with a maximum vertical displacement of ~40 cm. The main event was followed by a series of aftershocks, one of which had a magnitude of ML5.4. Using high-resolution aeromagnetic data, we analyse bedrock geology in a wide area surrounding the new scarp and map a series of major east–west-trending faults segmenting eight distinct geological domains, as well as a network of less prominent northwest-trending faults, one of which aligns with the southern segment of the scarp. Surface faulting, surface deformation and earthquake focal mechanism studies suggest movements on north- and northeast-trending structures. The main shock, the aftershocks, surface faulting and changes in InSAR-derived surface elevation all occur in a region bounded to the south by a prominent northwest-trending fault and to the north by a west-northwest-trending domain-bounding structure. Thus, we interpret the north-trending thrust fault associated with the main Lake Muir event as due to local stress concentration of the regional east–west stress field at the intersection of these structures. Further, we propose that a particularly large west-northwest-trending structure may be broadly focusing stress in the Lake Muir area. These findings encourage similar studies to be undertaken in other areas of Australia’s southwest to further the current understanding of seismic release in the region. <b>Citation: </b>S. Standen, M. Dentith & D. Clark (2021) A geophysical investigation of the 2018 Lake Muir earthquake sequence: reactivated Precambrian structures controlling modern seismicity,<i>Australian Journal of Earth Sciences</i>, 68:5, 717-730, DOI: 10.1080/08120099.2021.1848924

As part of the 2018 National Seismic Hazard Assessment (NSHA), we compiled the geographic information system (GIS) dataset to enable end-users to view and interrogate the NSHA18 outputs on a spatially enabled platform. It is intended to ensure the NSHA18 outputs are openly available, discoverable and accessible to both internal and external users. This geospatial product is derived from the dataset generated through the development of the NSHA18 and contains uniform probability hazard maps for a 10% and 2% chance of exceedance in 50 years. These maps are calculated for peak ground acceleration (PGA) and a range of response spectral periods, Sa(T), for T = 0.1, 0.2, 0.3, 0.5, 1.0, 2.0 and 4.0 s. Additionally, hazard curves for each ground-motion intensity measure as well as uniform hazard spectra at the nominated exceedance probabilities are calculated for key localities.

The local magnitude ML 5.4 (MW 5.1) Moe earthquake on 19 June 2012 that occurred within the Australian stable continental region was the largest seismic event for the state of Victoria for more than 30 years. Seismic networks in the southeast Australian region yielded many high-quality recordings of the moderate-magnitude earthquake mainshock and its largest aftershock (ML 4.4; MW 4.3) at a hypocentral range of 10 to 480 km. The source and attenuation characteristics of the earthquake sequence are analyzed. Almost 15,000 felt reports were received following the main shock, which tripped a number of coal-fired power generators in the region, amounting to the loss of approximately 1955 megawatts of generation capacity. The attenuation of macroseismic intensities are shown to mimic the attenuation shape of Eastern North America (ENA) models, but require an inter-event bias to reduce predicted intensities. Further instrumental ground-motion recordings are compared to ground-motion models (GMMs) considered applicable for the southeastern Australian (SEA) region. Some GMMs developed for ENA and for SEA provide reasonable estimates of the recorded ground motions of spectral acceleration within epicentral distances of approximately 100 km. The mean weighted of the Next Generation Attenuation-East GMM suite, recently developed for stable ENA, performs relatively poorly for the 2012 Moe earthquake sequence, particularly for short-period accelerations.