Tsunami Modelling Leads to Review of Evacuation Zones

Waimakariri Civil Defence will be reviewing tsunami evacuation zones following the completion of modelling that shows in worse-case scenarios, flooding could travel further inland than previously thought.

Environment Canterbury (ECan) commissioned GNS Science to model the impacts of various tsunami scenarios for North Pegasus Bay, after work completed for Christchurch last year resulted in larger evacuation zones for the city.

The report shows that the largest tsunami threats could affect areas of the District that are outside of the current evacuation zones, including parts of the Kaiapoi and Pegasus townships.

Waimakariri District Emergency Management Advisor, Brennan Wiremu is welcoming the modelling and says it will help the District be better prepared for tsunami risks.

“It was really important to have a full picture of how it could affect our District before making any changes,” Brennan Wiremu. “We’re now able to make decisions based on the latest and most accurate science available.”

Civil Defence are working with ECan, neighbouring Councils and local emergency services to draw up new tsunami evacuation zones and response plans. Brennan says they’re planning to have the new zones ready early in the New Year and they’ll be accompanied by a large public education campaign for the community.

“While it’s too early to say exactly what the new zones will look like, it’s likely to change from four distinct zones centred on our beach communities to a larger rectangle that extends the length of the coast,” said Brennan.

Modelling shows that the largest tsunami scenario that could affect the Waimakariri coast would be a large, rare tsunami from South America in which the District would have more than 12 hours of warning. Large, rare tsunamis from offshore North Island and Fiordland are also possible and could arrive in one to three hours, however most tsunami scenarios, including those from South America, would flood much less land than these ‘worst cases’.

Brennan says that Civil Defence is ready to respond to the threat of a tsunami but encourages residents to also have their own preparations in place at home.

“Our message hasn’t changed, if you feel an earthquake that is long or strong, get gone. Don’t wait for an official warning,” he says. “In all other cases, check the Council’s website or Facebook page for up-to-date information.”

He also encourages people who work or spend time in Christchurch to familiarise themselves with the city’s tsunami evacuation zones. More information can be found on the Christchurch City Council website.

The Council will update Waimakariri residents once the tsunami evacuation zones are reviewed and announced early next year. More information about the recent report can be found on ECan’s website.

Tsunami Safety:

  • Long or strong, get gone – if you feel a rolling-motion earthquake for longer than a minute or a strong earthquake that makes it hard to stand up, you need to leave. When the shaking stops, head immediately to the nearest high ground or as far inland as you can.
  • Stay Informed – keep checking official Civil Defence channels for up-to-date information. These include the Waimakariri District Council website and Facebook page, and radio stations such Compass 104.9 FM and Radio NZ.
  • Be prepared – emergencies can happen anytime, anywhere. Check out getready.govt.nz for tips to make sure you’re prepared.
  • Have a plan – have an evacuation plan and escape route for your household, including pets. Think about where you would go and, if possible, make arrangements with family or friends who live outside the tsunami zone to stay with them if you need to evacuate. Share any official warnings you hear with family and friends near the coast.
  • Think about - what your family would do if it happened during working hours or when the kids are at school. Does you know your school or preschool’s plan?