Authors / CoAuthors
Allen, T.I.
Abstract
<div>An earthquake catalogue based on the moment magnitude scale (<em>M</em>W) is a prerequisite for global best practice seismic hazard analyses. The 2018 National Seismic Hazard Assessment (NSHA18) was the first national-scale seismic hazard assessment for Australia to apply magnitude conversions to express earthquake magnitudes uniformly in terms of <em>M</em>W. This approach led to the single-biggest change in seismic hazard estimates between Geoscience Australia-led national seismic-hazard models. Between the 2012 and 2018 assessments, the hazard reduced because of: 1) the general reduction in the number of earthquakes of magnitude 4.0 and larger due to the correction of local magnitudes (<em>M</em>L) and subsequent conversion to <em>M</em>W, and; 2) the increase in the Gutenberg-Richter <em>b</em>-value due to the non-linear conversion of local magnitudes <em>M</em>L to <em>M</em>W.</div><div>Using a new continental-scale attenuation model, independent assessment of <em>M</em>W has been performed for over 300 earthquakes recorded between 1990 and September 2024. After recalculating <em>M</em>L for the same earthquakes using improved filtering and time-domain windowing criteria, the <em>M</em>W catalogue is used to test and validate the <em>M</em>L to <em>M</em>W conversion equations used in the 2023 National Seismic Hazard Assessment (NSHA23). The earthquakes are partitioned into their regional magnitude polygons as applied by Geoscience Australia in its real-time operations; notionally central and western Australia, South Australia (Mt Lofty and Flinders Ranges) and eastern Australia. The performance NSHA23 <em>M</em>L to <em>M</em>W conversion equation is then assessed for each of these magnitude regions. Overall, the NSHA23 <em>M</em>L to <em>M</em>W conversion performs very well relative to continental-scale earthquake dataset. The sensitivity of this conversion to an earthquake’s static stress drop is also assessed. There is evidence that minor adjustments could be applied to the NSHA23 <em>M</em>L–<em>M</em>W conversion equation for larger-magnitude events with high stress drops.</div><div><br></div> Presented at the Australian Earthquake Engineering Society (AEES) National Conference 2024
Product Type
document
eCat Id
149927
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Keywords
- ( Project )
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- 2023 National Seismic Hazard Assessment
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- earthquake catalogue
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- magnitude conversion
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- seismic hazard assessment
- theme.ANZRC Fields of Research.rdf
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- Seismology and Seismic Exploration
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- Published_External
Publication Date
2024-12-16T23:45:29
Creation Date
2024-09-27T16:00:00
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completed
Purpose
Reviews the performance of the 2023 National Seismic Hazard Assessment's magnitude conversion equations
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geoscientificInformation
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Australian Earthquake Engineering Society (AEES) National Conference, Novermber 21-23 2024, Adelaide, SA
Lineage
<div>Reviews the performance of the 2023 National Seismic Hazard Assessment magnitude conversion equations</div>
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[-44.00, -9.00, 112.00, 154.00]
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