East Coast Lab has developed an emergency planning toolbox to identify the consequences of a large earthquake in the Hikurangi subduction zone.

The Hikurangi subduction zone is located off the east coast of New Zealand and runs all along the Hawke's Bay coast.

"There's no avoiding the fact that all of Aotearoa New Zealand is at risk of earthquakes, and all of our coasts are at risk of tsunami," Hikurangi response planning project leader Natasha Blunden said.

"We know the Hikurangi subduction zone can produce large earthquakes and tsunami, and that these events have occurred in the past.

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"Planning for this certainty will help lift our country's readiness for, and resilience to, a future earthquake and tsunami on this fault."

The two-year Hikurangi response planning project was developed to support the five Civil Defence Emergency Management groups that would be most affected by a large Hikurangi event – Tairawhiti, Bay of Plenty, Hawke's Bay, Manawatu-Whanganui and Wellington.

"While scientists are carrying out more research to build a clearer picture of the hazard posed by the Hikurangi subduction zone, we know a rupture of some size in the future is certain."

The resource is intended to give emergency managers, local authorities and central government a greater understanding of the risk and inform regional response planning for such event.

It is based on a credible 8.9 magnitude earthquake and tsunami scenario developed by GNS Science.

Blunden said credible scenarios help in considering impact on things such as key infrastructure, communities and emergency services but while this scenario is scientifically credible, it is just one of the many possibilities and scientists cannot predict when or how a real event will occur.

It contains information about the hazard, its likelihood, vulnerability and consequences and a planning section with regional response planning considerations, recommendations key messages/resources for community engagement about the subduction zone.

The toolbox says that subduction zones are known for producing the largest earthquakes in the world such as the 2011 magnitude 9.1 earthquake and tsunami in Japan.

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Some of the consequences of such an event which are recognised in the toolbox are that there would be hundreds to thousands of fatalities, potentially tens of thousands of injuries, and tens of thousands of damaged buildings.

Blunden said that although the project was being driven by Civil Defence Emergency Management groups, people still need to make sure they understand the risks they face and prepare themselves.

"We are all responsible for ourselves and our families – we are all part of Civil Defence in New Zealand. And remember, if you feel a long or strong earthquake, don't wait for an official warning – if it's long or strong, get gone."

To access the toolbox, visit: https://www.eastcoastlab.org.nz/our-science/our-projects/hikurangiresponseplan/