Authors / CoAuthors
Allen, T.I.
Abstract
Prior to the development of Australian-specific magnitude formulae, the 1935 magnitude corrections by Charles Richter – originally developed for southern California – was almost exclusively used to calculate earthquake magnitudes throughout Australia prior to the 1990s. Due to the difference in ground-motion attenuation between southern California and much of Australia, many historical earthquake magnitudes are likely to be overestimated in the Australian earthquake catalogue. A method has been developed that corrects local magnitudes using the difference between the original (inappropriate) magnitude corrections and the Australian-specific corrections at a distance determined by the nearest recording station likely to have recorded the earthquake. These corrections have reduced the rates of local magnitudes of 4.5 in the historical catalogue by about 30% since 1900, while the number of magnitude 5.0 earthquakes has reduced by about 60% in the same time period. The reduction in the number of moderate-to-large-magnitude earthquakes over the instrumental period yields long-term earthquake rates that are more consistent with present-day rates, since the development of Australian-specific magnitude formulae. The adjustment of historical earthquake magnitudes is important for seismic hazard assessments, which assume a Poisson distribution of earthquakes in space and time.
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document
eCat Id
140159
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Keywords
- theme.ANZRC Fields of Research.rdf
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- Seismology and Seismic ExplorationEarthquake EngineeringEARTH SCIENCESNatural Hazards
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- Published_External
Publication Date
2021-06-01T05:08:39
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completed
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External Publication
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notPlanned
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geoscientificInformation
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Journal of Seismology
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[-44.00, -9.00, 112.00, 154.00]
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Spatial Resolution
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