Stochastic Ground-Motion Simulation of the 2021 Mw 5.9 Woods Point Earthquake: Facilitating Local Probabilistic Seismic Hazard Analysis in Australia

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Abstract

The 2021 Mw 5.9 Woods Point event is the largest onshore earthquake that has occurred in the recorded history of southeastern Australia since European settlement. To study its source and ground-motion characteristics and to extract information for local seismic hazard analysis, we employ a stochastic finite-fault simulation approach to simulate ground motions for this event based on the observations collected from 36 onshore stations. We determine the regional distance-dependent attenuation parameters using the horizontal Fourier acceleration amplitude spectrum in the frequency range of 0.1–20 Hz. We parameterize path parameters using different models to consider uncertainties and sensitivities. To investigate local site effects, we construct a VS30-based site amplification model. Source parameters are then determined by fitting the theoretical Brune’s ω2 model with a reference Fourier source spectrum at 1.0 km. The κ0 value for the reference rock site is estimated as κ0=0.01 s, and dynamic stress drop is found to be 41.0 MPa by minimizing the overall absolute residual of 5% damped pseudospectral acceleration. We validate the simulations by comparing simulated and observed ground motions in terms of various intensity measurements; analyses of residuals show that the simulations are in good agreement with observations (average residual is close to 0). To facilitate future probabilistic seismic hazard analysis, six selected ground-motion models are ranked using the deviance information criteria based on an independent data set consisting of field observations and simulated ground motions.
Original languageEnglish (US)
JournalBulletin of the Seismological Society of America
DOIs
StatePublished - May 31 2023

Bibliographical note

KAUST Repository Item: Exported on 2023-06-07
Acknowledged KAUST grant number(s): BAS/1/1339-01-01
Acknowledgements: The authors thank David Boore for the insightful suggestions on data analysis and result illustrations as well as the general discussions about several topics related to this article, which help to improve the quality of this article. The authors thank Trevor Allen (Geoscience Australia), Adam Pascale (Seismology Research Center), and Ryan Hoult (Université Catholique de Louvain in Belgium) for providing the recorded data of this event. The authors especially thank Trevor Allen for his general guidance on several topics, including raw data processing, site response determination, and so forth. The authors thank Adam Pascale, Januka Attanayake, and Abraham Jones (The University of Melbourne) for their help in removing the instrument response from the raw data. The authors thank David Love (Seismological Association of Australia Inc.) and Wayne Peck (Seismology Research Center) for their help in determining the source mechanism. Thanks also are given to Sigurjón Jónsson (King Abdullah University of Science and Technology [KAUST]), Milad Kowsari from Háskóli Íslands, Birgir Hrafnkelsson and Benedikt Halldórsson (University of Iceland) for sharing the Deviance information criterion (DIC) code. The three anonymous reviewers are thanked for their thoughtful and constructive comments to improve the quality of this article. The authors appreciate the assistance from the associate editor Ivan G. Wong for processing this article and his comments about the language editing. The research presented in this article is supported by King Abdullah University of Science and Technology (KAUST) in Thuwal, Saudi Arabia, Grant Number BAS/1/1339-01-01.

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics

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