Updated scientific information about the likely impacts of a tsunami on Christchurch has prompted a revision of the city’s evacuation zones.
The zones have been re-drawn because computer modelling commissioned by Environment Canterbury and Christchurch City Council shows that flooding from a tsunami may extend further inland than allowed for under the existing evacuation zones.
“The modelling done by GNS Science and NIWA was based on conservative, worst-case scenarios and shows there is potential for flooding further inland than previously envisaged from large tsunamis generated from the South and Central American coasts or the Kermadec subduction zone. Based on the modelling, we have extended the evacuation zones,’’ says Christchurch City Council Acting Head of Civil Defence and Emergency Management Rebecca Newton.
“The release today of the new evacuation zones is a stepping stone towards ensuring that people are aware of the tsunami risk and how they may be impacted.
“We have been working closely with at-risk communities over the past two years to ensure their evacuation planning is under way and we will be escalating that work in the new year.
“Our goal is to empower communities to develop their own evacuation plans and to make sure they understand what the new evacuation zones mean for them.
“In the meantime, I would encourage everyone to check our online map to see whether they are living or working in an evacuation zone so they can find out what they need to do if there is an emergency,’’ Ms Newton says.
In Christchurch, there are three evacuation zones – the red evacuation zone, the orange evacuation zone, and the yellow evacuation zone.
People who are in the red or orange evacuation zones should evacuate if they feel a long or strong earthquake, are told to by Civil Defence, or if they hear the tsunami sirens sound.
They should head immediately to the nearest high ground or well inland, and out of all the evacuation zones.
“If you live or work in an evacuation zone, you should have an evacuation plan in place. Talk to your family, neighbours and work colleagues about where you would go and which route you would take. An emergency can happen at any time so you need to be prepared,’’ Ms Newton says.
The Land Information Memorandums (LIMs) that Council holds for all properties across Christchurch will be updated to reflect the changes to the evacuation zones.
The Council will also be reviewing the Banks Peninsula evacuation zones once ECan-commissioned computer modelling of tsunami scenarios for that area have been completed.
Community drop-in sessions where people can learn more about the evacuation zones will be held on:
The Red evacuation zone covers areas that could be affected by a small tsunami that is unlikely to flood land but could cause strong surges or currents in the water. This includes the estuary, rivers, beaches and harbours.
The Orange evacuation zone covers low-lying coastal areas that are likely to be flooded in a large tsunami.
You should leave both the red evacuation zone and the orange evacuation zone if you:
Stay out of these zones until you are told it is safe to go back.
You can expect to evacuate the orange zone maybe a few times in your lifetime.
The Yellow evacuation zone covers areas that could potentially be flooded in a very large tsunami.
You do not need to leave this zone if you feel a long or strong earthquake.
If you hear the tsunami sirens, check to see if there is a Civil Defence official tsunami evacuation warning for the yellow zone. The warning is given on the radio, television, social media or through an Emergency Mobile Alert to your phone.
If there is an announcement to evacuate the yellow zone you must leave immediately.
If evacuated, stay out of this zone until you are told that it is safe to go back.
Areas outside the tsunami evacuation zones do not need to evacuate in a long or strong earthquake.