using cluster analysis to optimize tsunami evacuation zones
DESCRIPTION
Using Cluster Analysis to Optimize Tsunami Evacuation Zones. William Power, Biljana Lukovi ć GNS Science, Lower Hutt, New Zealand. New Zealand tsunami sources. Distant/Regional Earthquakes. Local Earthquakes. Background Figures from: Integrated Tsunami Database for Pacific. - PowerPoint PPT PresentationTRANSCRIPT
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Using Cluster Analysis to Optimize Tsunami Evacuation Zones
William Power, Biljana Luković
GNS Science, Lower Hutt, New Zealand
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GNS Science
New Zealand tsunami sources
Background Figures from: Integrated Tsunami Database for Pacific
Distant/Regional EarthquakesLocal Earthquakes
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GNS Science
Tsunami warnings
• Divide the coast into zones
• Assign a threat level for each zone, based on maximum predicted water level
• Example is based on shipping forecast zones – not optimised for tsunami
Tsunami threat levels
Source: Mw 9.1 Southern Peru (1868)
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GNS Science
Tsunami threat levels Tsunami threat levels
Source: Mw 9.1 Southern Peru (1868)
Source: Mw 9.1 Southern Peru (1868)
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GNS Science
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GNS Science
The Basic idea
Fault 1 Fault 2Max water level Fault 1
Max
wat
er le
vel F
ault
2
Cluster 1
Cluster 2
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GNS Science
Source locations
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GNS Science
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GNS Science
Colours indicate clusters
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GNS Science
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GNS Science
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GNS Science
Problem
• The standard algorithms for computing clusters do not require the members of the cluster to be contiguous
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GNS Science
No relationship between separated clusters of the same colour
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GNS Science
Conclusions
• New Zealand is exposed to tsunami from many directions
• Different parts of the coast are more/less susceptible to different source regions
• In a warning system based around zones it is beneficial if the coast within each zone has a similar pattern of susceptibility
• Cluster Analysis is one route for classifying stretches of coast according to their susceptibility to different sources
• A drawback of conventional cluster analysis is that it does not constrain the clusters to be contiguous around the coast
• Approaches to adding the contiguity constraint are possible, but more work is required
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GNS Science
Acknowledgments
• NOAA – use of MOST and FACTS
• Diana Greenslade (BOM) – discussions about warning zones
• David Rhoades (GNS) – discussions about statistical analysis