Authors / CoAuthors
Leonard, M. | Clark, D. | Burbidge, B. | Collins, C.
Abstract
The effect of ground motion models, site response and recurrence parameters (a, b, Mmax) on the uncertainty in estimating earthquake hazard have been widely discussed. There has been less discussion on the effect of the choice of source zones and the implied seismicity model. In the current Australian national seismic hazard map we have adopted a 3 layer source zone model. This attempts to capture the variability of the spatial distribution of the seismicity in the stable continental crust of Australia. PSHA has an implied assumption that the spatial distribution of earthquakes within a source zone is either uniform or random - with the random distribution approaching uniformity as it becomes sufficiently dense. At almost any scale in no area of Australia does the seismicity conform to either a random (single Poisson model) or a uniform distribution - it is more clustered. Generally, at least three Poisson models are required to match the observed spatial statistical distribution; typically zones of low, moderate and very high seismicity. Using the full (not declustered catalogue) at least 4 Poisson models are required. In all cases examined there are more bins than expected with <1 and >3 earthquakes and a deficit of bins with 1 or 2 earthquakes. This observaion is consistent with emerging models of earthquakes in stable continents being a non-stationary or episodic, rather than a steady state, process. In order to account for this observation, we use a three layer source zone model, consisting of: a Background layer, with three zones covering 100% of the continent, based on the geological and geophysical properties; a Regional layer, of 25 zones covering ~50% of the continent, based on the pattern of earthquake density; and a Hotspot layer, of 44 zones covering 2% of the continent, based on the areas of sustained intense seismicity. In the final hazard model the maximum of the three hazard values is used, not a weighted average of the three layers.
Product Type
nonGeographicDataset
eCat Id
73195
Contact for the resource
Custodian
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
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- GA PublicationAbstract
- ( Theme )
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- earthquakes
- ( Theme )
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- geohazards
- ( Theme )
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- seismology
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
Publication Date
2012-01-01T00:00:00
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geoscientificInformation
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