In 2009/2010 Environment Canterbury commissioned the National Institute of Water and Atmospheric Research (NIWA) to model inundation (flooding) along parts of the Canterbury coast from a 'worst-case' South American tsunami.
The project modelled how high above normal sea level a 'worst case' distant-source tsunami would be at the coast for the whole of Canterbury. This used a scenario based on the 1868 South American tsunami, which flooded a lot of land in Canterbury, and is one of the largest distant-source tsunamis we could expect.
The project then modelled how much land would be flooded from this sea level at the coast. Flooding on land was only modelled for areas where good topographic (land height) information was available. These areas were:
Christchurch City was not included in this modelling because distant-source tsunami models were already available for the area, and these had been used by Christchurch City Council and the New Zealand Police to determine coastal evacuation zones for Christchurch City in 2007. The 2009/2010 NIWA modelling concentrated on areas where there was no previous modelling available.
Download the report here - Modelling coastal inundation in Canterbury from a South American tsunami report (2011) (4.75 MB)
Following the 22 February 2011 earthquake Environment Canterbury, in collaboration with Christchurch City Council and Waimakariri District Council, decided to remodel the 1868 South American tsunami scenario (used for the above 2011 report) for Kaiapoi/Kairaki/Pines Beach, and to extend the modelling down the Christchurch coast to Taylors Mistake. This was done to see if changes were needed to the 2007 coastal evacuation plan for Christchurch due to earthquake-related subsidence in Christchurch, and to assist Waimakariri District Council to determine distant-source tsunami evacuation zones for Kaiapoi/Kairaki/Pines Beach using the most up-to-date land heights.
Download the report here - Modelling coastal inundation in Christchurch and Kaiapoi from a South American tsunami using topography from after the 2011 February earthquake report (2012) (2.35 MB)
Tsunami flooding from a 'worst case' distant-source tsunami was modelled for the Kaikoura coast from Oaro to Kekerengu in 2013. This used high resolution topographic (land height) data for the Kaikoura coast collected by Environment Canterbury in 2012, which wasn't available when the modelling for the rest of the Canterbury coast was done. This modelling uses the same scenario as other distant-source modelling done for the Canterbury coast - the 1868 South American tsunami. This is one of the largest distant-source tsunamis we would expect in Canterbury. The results show that expected flooding from this scenario is relatively minor compared to other parts of Canterbury, particularly Pegasus Bay and Banks Peninsula.
This report only looks at a distant-source tsunami from across the Pacific Ocean. Kaikoura is also vulnerable to local-source tsunamis created close to shore - see our Tsunami information for Kaikoura page for more information.
Download the report here - Tsunami inundation modelling for Kaikoura and North Canterbury report (2013) (1 MB)
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