The 2018 National Seismic Hazard Assessment for Australia – earthquake epicentre catalogue

Allen, Trevor I.; Leonard, Mark; Ghasemi, Hadi; Gibson, Gary

doi:10.11636/record.2018.030

Cited by 25 publications

(72 citation statements)

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“…This finding is consistent with an analysis of the expected relief generation rates by Leonard & Clark (2011) which imply that the historical catalogue of seismicity in the Southwest Seismic Zone (SWSZ) is ten times that required to build the scarps (see also Braun et al, 2009). However, revised earthquake rate estimates based on the remediation of catalogue magnitudes for the NSHA18 (Allen et al, 2018) suggest that long-term forecasts of large-earthquake rates in Precambrian crust may have been previously overestimated, which would provide an improved correspondence between the historical and pre-historical earthquake records.…”

Section: Migration Of the Locus Of Moment Release In The Southwest Sesupporting

confidence: 84%

“…Including eight of the nine earthquakes mentioned above, forty-two onshore earthquakes of magnitude MW ≥5.0 are located in the Australian Precambrian cratonic crust (cf. Allen et al, 2018). Given that hypocentres are typically extremely shallow in the cratonic areas (Clark et al, 2014a;Leonard, 2008), these events may also have ruptured the ground surface, in which case a landscape record may exist and could be investigated to help understand their structural context.…”

Section: Migration Of the Locus Of Moment Release In The Southwest Sementioning

confidence: 99%

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The 2018 Lake Muir earthquake sequence, southwest Western Australia: rethinking Australian stable continental region earthquakes

Clark¹,

Brennand²,

Brenn³

et al. 2019

Preprint

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Abstract. Modern geodetic and seismic monitoring tools are enabling the study of moderate-sized earthquake sequences in unprecedented detail. Here we use a variety of methods to examine surface deformation caused by a sequence of earthquakes near Lake Muir in southwest Western Australia in 2018. A shallow MW 5.3 earthquake on the 16th of September 2018 was followed on the 8th of November 2018 by a MW 5.2 event in the same region. Focal mechanisms for the events suggest reverse and strike-slip rupture, respectively. Interferometric Synthetic Aperture Radar (InSAR) analysis of the events suggests that the ruptures are in part spatially coincident. Field mapping, guided by the InSAR results, reveals that the first event produced an approximately 3 km long and up to 0.5 m high west-facing surface rupture, consistent with slip on a moderately east-dipping fault. Double difference hypocentre relocation of aftershocks using data from rapidly deployed seismic instrumentation confirms an east-dipping rupture plane for the first event, and shows a concentration located at the northern end of the rupture where the InSAR suggests greatest vertical displacement. The November event resulted from rupture on a northeast-trending strike-slip fault. UAV-derived digital terrain models (differenced with pre-event LiDAR) reveal a surface deformation envelope consistent with the InSAR for the first event, but could not discern deformation unique to the second event. New rupture length versus magnitude scaling relationships developed for non-extended cratonic regions as part of this study allow for the distinction between “visible” surface rupture lengths (VSRL) from field-mapping and “detectable” surface rupture lengths (DSRL) from remote sensing techniques such as InSAR, and suggest longer ruptures for a given magnitude than implied by commonly used scaling relationships.

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Section: Migration Of the Locus Of Moment Release In The Southwest Sesupporting

confidence: 84%

Section: Migration Of the Locus Of Moment Release In The Southwest Sementioning

confidence: 99%

The 2018 Lake Muir earthquake sequence, southwest Western Australia: rethinking Australian stable continental region earthquakes

Clark¹,

Brennand²,

Brenn³

et al. 2019

Preprint

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“…2. Development of a homogenised earthquake catalogue including conversion of local magnitudes to moment magnitudes (Ghasemi et al, 2016;Allen et al, 2018c); and 3. Inclusion of epistemic uncertainty in seismic source models (Griffin et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Expert elicitation of model parameters for the 2018 National Seismic Hazard Assessment: Summary of workshop, methodology and outcomes.

Griffin¹,

Gerstenberger²,

Allen³

et al. 2018

Self Cite

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“…Unless these conversions are time-dependent, they commonly assume that ML estimation has been consistent for the observation period. Consequently, for earthquakes in Australia, there is a need to correct pre-1990 magnitude estimates to ensure continuity with current observatory magnitude estimation methods [26]. Ideally, this could be achieved using original amplitude and period picks.…”

Section: Developing Consistent Cataloguesmentioning

confidence: 99%

Seismic Hazard Estimation in Stable Continental Regions: Does Psha Meet the Needs for Modern Engineering Design in Australia?

Allen

2020

BNZSEE

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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. 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 the context 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.

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The 2018 National Seismic Hazard Assessment for Australia – earthquake epicentre catalogue

Cited by 25 publications

References 0 publications

The 2018 Lake Muir earthquake sequence, southwest Western Australia: rethinking Australian stable continental region earthquakes

The 2018 Lake Muir earthquake sequence, southwest Western Australia: rethinking Australian stable continental region earthquakes

Expert elicitation of model parameters for the 2018 National Seismic Hazard Assessment: Summary of workshop, methodology and outcomes.

Seismic Hazard Estimation in Stable Continental Regions: Does Psha Meet the Needs for Modern Engineering Design in Australia?

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