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.

Geoscience Australia provides rapid, event-specific, earthquake information from its 24x7 earthquake information centre. Information in this service includes basic earthquake parameters (time, location and magnitude) and information about local effects including ground shaking (modelled). This includes all historic data.

Coseismically displaced rock fragments (chips) in the near-field (less than 5 km) of the 2016 moment magnitude (MW) 6.1 Petermann earthquake (Australia) preserve directionality of strong ground motions. Displacement data from 1437 chips collected over an area of 100 km2 along and across the Petermann surface rupture is interpreted to record combinations of co-seismic directed permanent ground displacements associated with elastic rebound (fling) and transient ground shaking, with intensities of motion increasing with proximity to the surface rupture. The observations provide a proxy test for available models for directionality of near-field reverse fault strong ground motions in the absence of instrumental data. This study provides a dense proxy record of strong ground motions at less than 5 km distance from a surface rupturing reverse earthquake, and may help test models of near-field dynamic and static pulse-like strong ground motion for dip-slip earthquakes.

The 20 May 2016 surface-rupturing intraplate earthquake in the Petermann Ranges is the largest onshore earthquake to occur in the Australian continent in 19 yr. We use in situ and Interferometric Synthetic Aperture Radar surface observations, aftershock distribution, and the fitting of P-wave source spectra to determine source properties of the Petermann earthquake. Surface observations reveal a 21-km-long surface rupture trace (strike = 294°±29°) with heterogeneous vertical displacements ( <0:1–0:96 m). Aftershock arrays suggest a triangular-shaped rupture plane (dip ≈ 30°) that intersects the subsurface projection of the major geophysical structure (Woodroffe thrust [WT]) proximal to the preferred location of the mainshock hypocenter, suggesting the mainshock nucleated at a fault junction. Footwall seismicity includes apparent southwest-dipping Riedel-type alignments, including possible activation of the deep segment of the WT. We estimate a moment magnitude (Mw) of 6.0 and a corner frequency (fc) of 0.2 Hz, respectively, from spectral fitting of source spectra in the 0.02–2 Hz frequency band. These translate into a fault area of 124 km2 and an average slip of 0.36 m. The estimated stress drop of 2.2 MPa is low for an intraplate earthquake; we attribute this to low-frictional slip (effective coefficient of friction >0:015) along rupture-parallel phyllosilicate-rich surfaces within the host rock fabric with possible additional contributions from elevated pore-fluid pressures.

Set of old historical documents including, Adelaide Observatory Seismological Bulletins, historical events, Stations installations, SA Activity Bulletins, Regional Events, Maintence Reports, Seismometer Handbooks and Rainfall Observations.

Damaging earthquakes in Australia and other regions characterised by low seismicity are considered low probability but high consequence events. Uncertainties in modelling earthquake occurrence rates and ground motions for damaging earthquakes in these regions pose unique challenges to forecasting seismic hazard, including the use of this information as a reliable benchmark to improve seismic safety within our communities. Key challenges for assessing seismic hazards in these regions are explored, including: the completeness and continuity of earthquake catalogues; the identification and characterisation of neotectonic faults; the difficulties in characterising earthquake ground motions; the uncertainties in earthquake source modelling, and the use of modern earthquake hazard information to support the development of future building provisions. Geoscience Australia 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 have challenged notions of seismic hazard in Australia in terms of the recurrence of damaging ground motions. Consequently, this raises the question of whether current practices in probabilistic seismic hazard analysis (PSHA) deliver the outcomes required to protect communities and infrastructure assets in low-seismicity regions, such as Australia. This manuscript explores a range of measures that could be undertaken to update and modernise the Australian earthquake loading standard, in light of these modern seismic hazard estimates, including the use of alternate ground-motion exceedance probabilities for assigning seismic demands for ordinary-use structures. The estimation of seismic hazard at any location is an uncertain science, particularly in low-seismicity regions. However, as our knowledge of the physical characteristics of earthquakes improve, our estimates of the hazard will converge more closely to the actual – but unknowable – (time independent) hazard. Understanding the uncertainties in the estimation of seismic hazard is also of key importance, and new software and approaches allow hazard modellers to better understand and quantify this uncertainty. 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.

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

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

Damaging earthquakes in Australia and other regions characterised by low seismicity are considered low probability but high consequence events. Uncertainties in modelling earthquake occurrence rates and ground motions for damaging earthquakes in these regions imposes unique challenges on forecasting seismic hazard and the use of this information for improving seismic safety within our communities. Key challenges for these regions are explored, including: the quality and continuity of earthquake catalogues; the difficulties in characterising earthquake ground motions; the uncertainties in earthquake source modelling, and; the consideration of modern earthquake hazard information to support future building provisions.

This document reports on a Bushfire and Natural Hazards Collaborative Research Centre (BNHCRC) utilisation project that has sought to develop information on the most effective means to address York’s high risk buildings. It has also sought to develop a better understanding of the logistics that would be faced by the state emergency services and the local shire council in a rare but credible earthquake. The utilisation project is entitled “Earthquake Mitigation of WA Regional Towns: York Case Study”, and sits under the over-arching BNHCRC Project A9 “Cost-effective Mitigation Strategy Development for Building Related Earthquake Risk”. The work commenced in January 2018 and was undertaken over a two year period. It involved the University of Adelaide and Geoscience Australia as the CRC research partners, and DFES and the Shire of York as the end users. The WA DPLH has also been a participant, though not a formal BNHCRC end user. The project had the following key components:- • Develop a building, business and demographic exposure database for York with the attributes collected tailored for modelling earthquake impact and for quantifying avoided consequences in economic terms. • Examine the benefits and costs of retrofitting old URM buildings to improve the resilience of them to earthquake. This is to range in scale from individual households and businesses up to the community as a whole. • Prepare earthquake impact scenarios suitable for emergency management planning by DFES and the Shire of York.