Product catalogue
From offshore to onshore probabilistic tsunami hazard assessment via efficient Monte-Carlo sampling
Offshore Probabilistic Tsunami Hazard Assessments (offshore PTHAs) provide large-scale analyses of earthquake-tsunami frequencies and uncertainties in the deep ocean, but do not provide high-resolution onshore tsunami hazard information as required for many risk-management applications. To understand the implications of an onshore PTHA for the onshore hazard at any site, in principle the tsunami inundation should be simulated locally for every scenario in the offshore PTHA. In practice this is rarely feasible due to the computational expense of inundation models, and the large number of scenarios in offshore PTHAs. Monte-Carlo methods offer a practical and rigorous alternative for approximating the onshore hazard, using a random subset of scenarios. The resulting Monte-Carlo errors can be quantified and controlled, enabling high-resolution onshore PTHAs to be implemented at a fraction of the computational cost.
This study develops novel Monte-Carlo sampling approaches for offshore-to-onshore PTHA. Modelled offshore PTHA wave heights are used to preferentially sample scenarios that have large offshore waves near an onshore site of interest. By appropriately weighting the scenarios, the Monte-Carlo errors are reduced without introducing any bias. The techniques are applied to a high-resolution onshore PTHA for the island of Tongatapu in Tonga. In this region, the new approaches lead to efficiency improvements equivalent to using 4-18 times more random scenarios, as compared with stratified-sampling by magnitude, which is commonly used for onshore PTHA. The greatest efficiency improvements are for rare, large tsunamis, and for calculations that represent epistemic uncertainties in the tsunami hazard.
To facilitate the control of Monte-Carlo errors in practical applications, this study also provides analytical techniques for estimating the errors both before and after inundation simulations are conducted. Before inundation simulation, this enables a proposed Monte-Carlo sampling scheme to be checked, and potentially improved, at minimal computational cost. After inundation simulation, it enables the remaining Monte-Carlo errors to be quantified at onshore sites, without additional inundation simulations. In combination these techniques enable offshore PTHAs to be rigorously transformed into onshore PTHAs, with full characterisation of epistemic uncertainties, while controlling Monte-Carlo errors.
Appeared online in Geophysical Journal International 11 April 2022.
Simple
Identification info
- Date (Creation)
- 2022-04-11
- Date (Publication)
- 2022-05-02T07:45:51
- Citation identifier
- Geoscience Australia Persistent Identifier/https://pid.geoscience.gov.au/dataset/ga/146012
Identifier
- Codespace
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Digital Object Identifier
- Cited responsible party
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Role Organisation / Individual Name Details Author Davies, G.
PSCD Internal Contact Author Weber, R.
PSCD Internal Contact Author Wilson, K.
PSCD Internal Contact Author Cummins, P.
PSCD Internal Contact
- Purpose
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External Publication Journal Article
- Status
- Completed
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Role Organisation / Individual Name Details Point of contact Commonwealth of Australia (Geoscience Australia)
Voice Point of contact Davies, G.
PSCD Internal Contact Resource provider Place, Space and Communities Division
External Contact
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- Geoscientific information
Extent
Extent
))
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- As needed
Resource format
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Product data repository: Various Formats
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Data Store directory containing the digital product files
Data Store directory containing one or more files, possibly in a variety of formats, accessible to Geoscience Australia staff only for internal purposes
- theme.ANZRC Fields of Research.rdf
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EARTH SCIENCES
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- GCMD Keywords
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Earth Science | Oceans | Ocean Waves | Tsunamis
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Earth Science | Human Dimensions | Natural Hazards | Tsunamis
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Earth Science | Solid Earth | Tectonics | Earthquakes | Earthquake Magnitude/Intensity
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- Keywords
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Tsunamis
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- Keywords
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Statistical Methods
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- Keywords
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Numerical approximations and analysis
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Published_External
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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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Australian Government Security ClassificationSystem
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- 2018-11-01T00:00:00
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- Unclassified
- Language
- English
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- UTF8
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Role Organisation / Individual Name Details Distributor Commonwealth of Australia (Geoscience Australia)
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Link to Article
Link to Article
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Metadata constraints
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Australian Government Security Classification System
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Metadata
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urn:uuid/5dd4531d-2c07-44ab-b1af-d6ba3530e25c
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GeoNetwork UUID
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Role Organisation / Individual Name Details Point of contact Commonwealth of Australia (Geoscience Australia)
Voice Owner Davies, G
Geoscience Australia Internal Contact Point of contact Davies, G.
PSCD Internal Contact
Type of resource
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- Document
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External Publication
Alternative metadata reference
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Geoscience Australia - short identifier for metadata record with
uuid
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- Date info (Creation)
- 2019-04-08T01:55:29
- Date info (Revision)
- 2019-04-08T01:55:29
Metadata standard
- Title
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AU/NZS ISO 19115-1:2014
Metadata standard
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ISO 19115-1:2014
Metadata standard
- Title
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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
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