The 2018 Lake Muir earthquake sequence, southwest Western Australia: rethinking the relationship between magnitude and surface rupture length for Australian stable continental region earthquakes
Modern geodetic and seismic monitoring tools are enabling the study of moderate-sized earthquake sequences in unprecedented detail. Discrepancies are apparent between the surface deformation envelopes ‘detectable’ using these tools, and ‘visible’ to traditional ground-based methods of observation. As an example, we compare the detectible and visible 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 and deformed the Earth’s surface over ~ 12 km in an east-west direction and ~ 8 km in a north-south direction. 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. No surface deformation unique to the second event was identifiable on the ground. 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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- Date (Publication)
- 2019-11-29
- Date (Revision)
- 2020-01-06T02:51:23
- Citation identifier
- Geoscience Australia Persistent Identifier/https://pid.geoscience.gov.au/dataset/ga/132519
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Digital Object Identifier
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Role Organisation / Individual Name Details Author Clark, D.J.
Author Allen, T.I.
Author Brennand, S.
Author Brenn, G.
Author Garthwaite, M.C.
Author Standen, S.
- Purpose
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Australian Earthquake Engineering Society Conference 2019 Newcastle NSW
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- Final
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Role Organisation / Individual Name Details Point of contact Commonwealth of Australia (Geoscience Australia)
Voice Point of contact Clark, D.J.
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- Geoscientific information
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EARTH SCIENCES
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Earthquake Engineering
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Natural Hazards
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Creative Commons Attribution 4.0 International Licence
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CC-BY
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4.0
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Australian Government Security ClassificationSystem
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- 2018-11-01T00:00:00
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- English
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Link to the paper (pdf)
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pdf
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Australian Government Security Classification System
- Edition date
- 2018-11-01T00:00:00
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- Unclassified
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urn:uuid/1d52afcf-55c7-480d-b73a-9510a7e01adc
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- English
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Role Organisation / Individual Name Details Point of contact Commonwealth of Australia (Geoscience Australia)
Voice Point of contact Clark, D.J.
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GA publication: conference paper
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Geoscience Australia - short identifier for metadata record with
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- 2019-04-08T01:55:29
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- 2019-04-08T01:55:29
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AU/NZS ISO 19115-1:2014
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ISO 19115-1:2014
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ISO 19115-3
- Title
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Geoscience Australia Community Metadata Profile of ISO 19115-1:2014
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Version 2.0, September 2018
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- https://pid.geoscience.gov.au/dataset/ga/122551