The Earthquake Scenario Selection is an interactive tool for querying, visualising and downloading earthquake scenarios. There are over 160 sites nationally with pre-generated scenarios available. These represent plausible future scenarios that can be used for earthquake risk management and planning (see https://www.ga.gov.au/about/projects/safety/nsha for more details).

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.

Damaging earthquakes in Australia and other regions characterised by low seismicity are considered low probability, high consequence events. Uncertainties in modeling earthquake occurrence rates and ground motions pose unique challenges to forecasting seismic hazard in these regions. In 2018 Geoscience Australia released its 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 (AEP) relative to the factors in the Australian earthquake loading standard; the AS1170.4. Due to concerns that the 1/500 AEP hazard factors proposed in the NSHA18 would not assure life safety throughout the continent, the amended AS1170.4 (revised in 2018) retains seismic demands developed in the early 1990s and also introduces a minimum hazard design factor of Z = 0.08 g. The hazard estimates from the NSHA18 have challenged notions of seismic hazard in Australia in terms of the probability of damaging ground motions and raises questions as to whether current practices in probabilistic seismic hazard analysis (PSHA) deliver the outcomes required to protect communities in low-seismicity regions, such as Australia. By contrast, it is also important that the right questions are being asked of hazard modelers in terms of the provision of seismic demand objectives that are fit for purpose. In the United States and Canada, a 1/2475 AEP is used for national hazard maps due to concerns that communities in low-to-moderate seismicity regions are considerably more at risk to extreme ground-motions. The adoption of a 1/2475 AEP seismic demands within the AS1170.4 would bring it in to line with other international building codes in similar tectonic environments and would increase seismic demand factors to levels similar to the 1991 hazard map. This, together with other updates, may be considered for future revisions to the standard. Presented at the Technical Sessions of the 2021 Seismological Society of America Annual Meeting (SSA)

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.

One-dimensional shear-wave velocity (VS ) profiles are presented at 50 strong motion sites in New South Wales and Victoria, Australia. The VS profiles are estimated with the spectral analysis of surface waves (SASW) method. The SASW method is a noninvasive method that indirectly estimates the VS at depth from variations in the Rayleigh wave phase velocity at the surface.

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.

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.

The Mwp 6.1 Petermann Ranges earthquake that occurred on 20 May, 2016 in the Central Ranges, NT, is the largest onshore earthquake to be recorded in Australia since the 1988 Tennant Creek sequence. While geodetic and geophysical analyses have characterized the extent of surface rupture and faulting mechanism respectively, a comprehensive aftershock characterization has yet to be performed. Data has been acquired from a 12-station temporary seismic network deployed jointly by the ANU and Geoscience Australia (GA), collected from five days following the mainshock to early October. Taking advantage of enhanced automatic detection techniques using the SeisComP3 real-time earthquake monitoring software within the National Earthquake Alerts Centre (NEAC) at GA, we have developed a comprehensive earthquake catalogue for this mainshock-aftershock sequence. Utilising the NonLinLoc location algorithm combined with a Tennant Creek-derived velocity model, we have preliminarily located over 5,800 aftershocks. With additional spatio-temporal analyses and event relocation, our objective will be to use these aftershocks to help delineate the geometry of the headwall rupture along the Woodroffe Thrust. These high-resolution aftershock detection techniques are intended to be implemented in real-time within the NEAC following future significant Australian intraplate earthquakes. This paper was presented at the Australian Earthquake Engineering Society 2021 Virtual Conference, Nov 25 – 26.

The preliminary 6th Generation seismic hazard model of Canada (CanadaSHM6-trial) provides the basis for design values proposed for the 2020 edition of the National Building Code of Canada (NBCC2020). Seismic hazard values at a probability level of 2% in 50 years for 679 Canadian localities are provided in an accompanying spreadsheet to supplement the public review of the seismic hazard portion of NBCC2020 scheduled from January to March 2020. The spreadsheet tool provides the ability to select a Canadian locality and visualize seismic hazard values for any value of VS30 (140 - 3000 m/s) and Site Class (E-A). In this document we provide detailed instructions on the use of this spreadsheet. This work will be superseded by a forthcoming Open File, once NBCC2020 is finalized to reflect the final seismic hazard values calculated using CanadaSHM6.

Geoscience Australia and the NSW Department of Industry undertook seismic monitoring of the NSW CSG extraction area in Camden as well as baseline monitoring in the region between 2015 and 2019. Geoscience Australia established and maintained seismic stations to identify of events of greater than ML2.0 within the CSG fields. Three new seismic stations were located near Camden CSG area with two baseline stations in North-West Sydney. This poster details the station builds and seismic monitoring of both the Camden CSG production area and the wider region during the project.