Authors / CoAuthors
Leonard, M.
Abstract
<p>The hazard factors in every version of AS 1170.4 since 1993 have been based on a seismic hazard map published in 1991. In this paper I statistically test the validity of that 1991 map. <p>Two methods are used to calculate the hazard for 24+ sites across Australia. Firstly, for each site I calculate how many standard deviations (?1) separate the 1991 hazard value from the calculated PSHA value. Secondly, the magnitude frequency distribution (MFD; i.e. a and b values) is adjusted so that the calculated hazard matches the 1991 hazard value. The number of standard deviations (?2) in the MFD that separate the adjusted MFD differs from the best estimate MFD is subsequently calculated. The first method was applied using four seismic source models (AUS6, DIM-AUS, NSHM13 and these combined), while the second method used NSHM13 only. The average number of standard deviations was calculated from the best 20 of the 24 sites. These statistics are considered a test the validity of the 1991 map. The two methods using five models in total all give similar results. The 1991 map is found, on average, to overestimate the hazard by 3 standard deviations. This suggests that the 1991 map is best described as a 95th+ percentile map. <p>Practitioners using this map, whether for setting building standards or assessing insurance exposure, need to be conscious that the seismic design values are not scientifically valid relative to modern mean probabilistic seismic hazard assessments.
Product Type
document
eCat Id
123888
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Keywords
- ( Sub-Topic Category )
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- earthquake hazard
- theme.ANZRC Fields of Research.rdf
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- EARTH SCIENCES
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- Published_External
Publication Date
2020-05-12T00:36:48
Creation Date
2018-11-01T00:00:00
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completed
Purpose
Conference Paper
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notPlanned
Topic Category
geoscientificInformation
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Extents
[-44, -9, 112, 154]
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Spatial Resolution
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