Emergency Management Otago
11 October 2017
Communities around Otago’s coast now have more certainty about which areas they should leave when a tsunami threatens, after Emergency Management Otago released online maps of evacuation zones today.
The detailed maps show three zones, coloured red, orange and yellow. Group Controller Chris Hawker said that the maps should provide certainty and a level of reassurance to people who were unsure about when they should leave low-lying areas of the coast, and how far they would have to move to reach safety.
The maps can be viewed on any computer or mobile device. The scale ranges from a bird’s eye view of the whole Otago coastline to a close-up of an individual property. There is also a simple search function that allows users to type in an address and see whether it is in an evacuation zone.
Mr Hawker said that several sources of information had been used to compile the maps. They include detailed GIS data on the Otago coast, geological and seismic information about where a tsunami could be generated by offshore earthquakes, modelling, and what is known about the impact of historic tsunamis here and elsewhere in New Zealand.
The red zone includes the whole of the Otago shore and all beaches, including the Otago Harbour. This area is at risk from a tsunami of any size, including those designated a “beach and marine threat” rather than a “land threat”.
The orange zone includes land close to sea level including estuaries and the lower reaches of several rivers. These areas are at risk from tsunami with a wave height of between 1 and 3 metres above high tide level.
People in both the red and orange evacuation zones are advised to get out of the water, off beaches and move inland or uphill immediately they feel a long or strong earthquake, without waiting for an official warning.
The yellow zone is based on the area that would be affected by a wave height more than three metres above high tide level. Mr Hawker said that a very large tsunami coming from a distant source – for example, South America – would prompt evacuations in the yellow zones.
Mr Hawker said that the maps allowed people who lived or worked along the coast to be better prepared in the event of a tsunami. They built on the national tsunami awareness campaign, with its simple message of “Long, Strong – Get Gone” based on the natural warning signs of prolonged and severe shaking.
“Last November when we had the tsunami warning after the Kaikoura earthquake, there was a lot of confusion about who should evacuate and where they ought to go. The mapping project will give people much more certainty about what they should prepare for.
“We expect that the maps will start some conversations between neighbours and within communities about where their best evacuation routes are, and who might need help to move in a hurry. That sort of local knowledge is so important.”
Mr Hawker said that Emergency Management Officers working in the Waitaki and Clutha Districts and Dunedin City would be supporting coastal communities to develop their own response plans. “We’re expecting that the release of these maps will get a lot of people thinking about what this means for them.”