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.

Seismic hazard modelling is a multi-disciplinary science that aims to forecast earthquake occurrence and its resultant ground shaking. Such seismic hazard models consist of a probabilistic framework that models the flow of uncertainty across a complex system; typically, this includes at least two model-components developed from earth science: seismic source models, and ground motion prediction models. Although there is no scientific prescription for the length of the forecasting time-window, the most common probabilistic seismic hazard analyses (PSHA hereafter) consider forecasting probabilities of ground shaking in time windows of 30 to 50 years. These types of models are the target of this review paper. Although the core methods and assumptions of such a modelling have largely remained unchanged since they were first developed more than 50 years ago, we will review the most recent initiatives which are facing the difficult task of meeting both the increasingly sophisticated demands of society and keeping pace with advances in our scientific understanding. A need for more accurate and precise hazard forecasting must be balanced with increased quantification of uncertainty and new challenges such as moving from time-independent hazard to forecasts that are time-dependent and specific to the time-period of interest. Meeting these challenges requires the development of science-driven models which integrate at best all information available, the adoption of proper mathematical frameworks to quantify the different types of uncertainties in the source and ground motion components of the hazard model, and the development of a proper testing phase of the hazard model to quantify the consistency and skill of the hazard model. We review the state-of-the-art of the national seismic hazard modeling, and how the most innovative approaches try to address future challenges.

The Philippine archipalego is tectonically complex and seismically hazardous, yet few seismic hazard assessments have provided national coverage. This paper presents an updated probabilistic seismic hazard analysis for the nation. Active shallow crustal seismicity is modeled by faults and gridded point sources accounting for spatially variable occurrence rates. Subduction interfaces are modelled with faults of complex geometry. Intraslab seismicity is modeled by ruptures filling the slab volume. Source geometries and earthquake rates are derived from seismicity catalogs, geophysical datasets, and historic-to-paleoseismic constraints on fault slip rates. The ground motion characterization includes models designed for global use, with partial constraint by residual analysis. Shallow crustal faulting near metropolitan Manila, Davao, and Cebu dominates shaking hazard. In a few places, peak ground acceleration with 10% probability of exceedance in 50 years on rock reaches 1.0 g. The results of this study may assist in calculating the design base shear in the National Structural Code of the Philippines.

At its nearest, northern Australia is just over 400 km from an active convergent plate margin. This complex and unique tectonic region combines active subduction and the collision of the Sunda-Banda Arc with the Precambrian North Australian Craton (NAC) near the Timor Trough and continues through to the New Guinea Highlands. Ground-motions generated from earthquakes on these structures have particular significance for northern Australian communities and infrastructure projects, with several large earthquakes in the Banda Arc region having caused ground-shaking-related damage in the northern Australian city of Darwin over the historical period. There are very few, if any, present-day tectonic analogs where cold cratonic crust abuts a convergent tectonic margin with subduction and continent-continent collision. Ground motions recorded from earthquakes in typical subduction environments are highly attenuated as they travel through young sediments associated with forearc accretionary prisms and volcanic back-arc regions. In contrast, seismic energy from earthquakes in the northern Australian plate margin region are efficiently channelled through the low-attenuation NAC, which acts as a waveguide for high-frequency earthquake shaking. As such, it is difficult to select models appropriate to the region for seismic hazard assessments. The development of a far-field ground-motion model to support future seismic hazard assessments for northern Australia is discussed. In general, the new model predicts larger ground motions in Australia from plate margin sources than models used for the 2018 National Seismic Hazard Assessment of Australia, none of which were considered fully appropriate for the tectonic environment. Short-period ground motions are strongly dependent on hypocentral depth and are significantly higher than predictions from commonly-used intraslab ground-motion models at comparable distances. The depth dependence in ground motion diminishes with increasing spectra periods. <b>Cite this article as</b> Allen, T. I. (2021). A Far-Field Ground-Motion Model for the North Australian Craton from Plate-Margin Earthquakes, <i>Bull. Seismol. Soc. Am. </i><b> 112</b>, 1041–1059, doi: 10.1785/0120210191

A database of recordings from moderate-to-large magnitude earthquakes is compiled for earthquakes in western and central Australia. Data are mainly recorded by Australian National Seismograph Network (ANSN), complemented with data from temporary deployments, and covering the period of 1990 to 2019. The dataset currently contains 1497 earthquake recordings from 164 earthquakes with magnitudes from MW 2.5 to 6.1, and hypocentral distances up to 1500 km. The time-series data are consistently processed to correct for the instrument response and to reduce the effect of background noise. A range of ground-motion parameters in the time and frequency domains are calculated and stored in the database. Numerous near-source recordings exceed peak accelerations of 0.10 g and range up to 0.66 g, while the maximum peak velocity of the dataset exceeds 27 cm/s. In addition to its utility for engineering design, the dataset compiled herein will improve characterisation of ground-motion attenuation in the region and will provide an excellent supplement to ground-motion datasets collected in analogue seismotectonic regions worldwide. This paper was presented at the Australian Earthquake Engineering Society 2021 Virtual Conference, Nov 25 – 26.

The 22 September 2021 (AEST) moment magnitude MW 5.9 Woods Point earthquake was the largest in the state of Victoria’s recorded history. The ground motions were felt throughout the state of Victoria and into neighbouring states New South Wales and South Australia. Minor damage was reported in the city of Melbourne and in some regional towns close to the epicentre. This event was captured on many high-quality recorders from multiple sources, including private, university, and public stations. These recordings provide a rare opportunity to test the validity of some ground motion models thought to be applicable to the southeast region of Australia. This paper presents spectral acceleration and attenuation comparisons of the Woods Point earthquake event to some ground motion models. The results of this paper provide further evidence that the attenuation characteristics of southeastern Australia may be similar to that in central and eastern United States, particularly at shorter distances to the epicentre. This paper was presented at the Australian Earthquake Engineering Society 2021 Virtual Conference, Nov 25 – 26.

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 6th Generation Seismic Hazard Model of Canada (CanadaSHM6) provides the basis for seismic design values proposed by Natural Resources Canada for the 2020 edition of the National Building Code of Canada (NBCC 2020). This Open File includes OpenQuake compatible source model files that will generate seismic hazard values as currently being proposed. Once NBCC 2020 is finalized, this report will be superseded by a subsequent Open File, to document the final model used to generate seismic hazard values using CanadaSHM6 for NBCC 2020.

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)

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.