Style and timing of late Quaternary faulting on the Lake Edgar Fault, southwest Tasmania, Australia: implications for hazard assessment in intracratonic areas

Geomorphic mapping of the ~30 km Lake Edgar fault scarp in SW Tasmania suggests that three large surface-rupturing events with vertical displacements of 2.4 - 3.1 m have occurred in late Quaternary times. Optically stimulated luminescence (OSL) chronology from a sequence of three periglacial fluvial terraces associated with scarp incision provides constraint on the age of these events. The ages of alluvial/colluvial fans derived from the youngest fluvial terraces constrain the most recent event to ca 17 - 18 ka. The chronology of the two preceding events is more poorly constrained. The near coincidence of ages from the base of the youngest terrace and the penultimate terrace suggest that penultimate faulting might have occurred during active fluvial deposition ca 25 - 28 ka. The oldest recognised event occurred subsequent to the ca 61 ka deposition of gravels on the highest of the three terraces and prior to the deposition of ca 48 ka gravels exposed in the footwall fan. The vertical displacement implies earthquake magnitudes in the order of MW 6.8 - 7.0. Estimates for the average slip rate calculated for the two complete seismic cycles range from 0.17 - 0.20 mm/yr (unweighted mean). This sequence represents the first recurrence data for surface-rupturing earthquakes on an eastern Australian Quaternary fault. The Lake Edgar Fault, which originally formed in the Palaeozoic, is undoubtedly susceptible to reactivation under conditions imposed by the contemporary Australian intraplate stress field. While displaying episodic rupture behaviour, the fault appears to rupture with a "characteristic" magnitude. These findings are significant for seismic hazard assessment both in Australia and in intracratonic areas worldwide.

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Date (Publication)
2004-06-22T00:00:00
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Geoscience Australia Persistent Identifier/https://pid.geoscience.gov.au/dataset/ga/61364

Cited responsible party
Role Organisation / Individual Name Details
Author

Clark, D.

 1
Author

Cupper, M.

 2
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Sandiford, M.

 3
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Kiernan, K.

 4
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MNHD
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Commonwealth of Australia (Geoscience Australia)

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  • Geoscientific information

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Product data repository: Various Formats

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FILE:DATA-DIRECTORY

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Data Store directory containing the digital product files

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Data Store directory containing one or more files, possibly in a variety of formats, accessible to Geoscience Australia staff only for internal purposes

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  • climate

  • earthquakes

  • geohazards

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Australian and New Zealand Standard Research Classification (ANZSRC)

  • Earth Sciences

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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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http://creativecommons.org/licenses/

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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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Non geographic dataset
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Australian Government Security ClassificationSystem

Edition date
2018-11-01T00:00:00
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https://www.protectivesecurity.gov.au/Pages/default.aspx

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Unclassified

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English
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UTF8
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Commonwealth of Australia (Geoscience Australia)

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nonGeographicDataset

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Geoscience Australia - short identifier for metadata record with

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eCatId/61364

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https://ecat.ga.gov.au/geonetwork/srv/eng/catalog.search#/metadata/a05f7892-c1e8-7506-e044-00144fdd4fa6

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https://ecat.ga.gov.au:80/geonetwork/srv/eng/catalog.search#/metadata/a05f7892-c1e8-7506-e044-00144fdd4fa6

Date info (Revision)
2018-04-10T11:27:42
Date info (Creation)
2004-06-22T00:00:00

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AU/NZS ISO 19115-1:2014

Metadata standard

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ISO 19115-1:2014

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ISO 19115-3

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Geoscience Australia Community Metadata Profile of ISO 19115-1:2014

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Version 2.0, September 2018

Citation identifier
https://pid.geoscience.gov.au/dataset/ga/122551

 
 

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climate earthquakes geohazards

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