Bay of Plenty tsunami risk zones shift inland as maps are updated

The Waihī Beach evacuation zone has extended further inland across parts of the town, which means some people might need to evacuate further inland to reach safety. Image / BOP Civil Defence

In contrast, parts of the evacuation zones in Katikati and Ōmokoroa have reduced, meaning fewer households are now included in the area required to evacuate.

Across Tauranga city, Miller said changes were generally more incremental, but some areas stood out.

In Ōtūmoetai, the evacuation zone now extends into additional low‑lying areas, including around the Woolworths supermarket and the local golf club.

One of the more prominent changes in Tauranga was in Ōtūmoetai where the evacuation zone has extended further into more low-lying areas, including the Woolworths supermarket and the golf club. Image / BOP Civil Defence

A notable shift across the region was the way evacuation zones now extended further inland along river and stream pathways.

Miller said rivers such as the Wairoa, Waimapu and Kaituna were good examples of this change.

He said the evacuation zones were largely informed by recent tsunami modelling, which takes into account factors such as ocean and harbour bathymetry (the study and mapping of underwater depth), coastal and inland landscapes, potential tsunami source locations and wave behaviour.

Modelling, however, was not the only consideration.

For example, whether people could practically and safely evacuate to certain locations.

People in Mount Maunganui are advised to head to Mount Drury or Blake Park / Bay Oval in the event of a tsunami, with Mauao closed due to landslide damage. Image / BOP Civil Defence

He said improvements in scientific knowledge and modelling technology were likely behind many changes now reflected in the maps.

“Our understanding of tsunami behaviour and our environment continues to improve, and the technology used for modelling is constantly being refined based on the latest research. All of that influences the evacuation zones we set.”

The updated maps replace versions introduced in 2023, when the region shifted from a red‑orange‑yellow system based on different tsunami scenarios to a single “blue zone” showing the areas that need to be evacuated.

More than 150 tsunami evacuation signboards across coastal Bay of Plenty were being updated to match the new maps.

Digital versions were published on the Bay of Plenty Civil Defence website and local council sites.

In a media statement, Emergency Management Bay of Plenty regional manager Jono Gracie urged residents to check the updated maps and ensure they understand what they mean for their household or workplace.

Bay of Plenty holidaymakers in Northland at Waitangi Golf Course during a tsunami evacuation in 2021. Photo / Peter De Graaf

People should consider the map in their household evacuation plan and practice their tsunami hīkoi or evacuation route, Gracie said.

“In an emergency, any means of evacuation that doesn’t add to traffic congestion should be considered, including walking or cycling where possible.”

He stressed that in a locally generated tsunami, there may be no time for an official warning.

“If an earthquake is long or strong, get gone,” Gracie said. “Natural warning signs such as sudden sea level changes or loud, unusual ocean noises mean people should act immediately.”

More information, including updated evacuation maps and tsunami preparedness advice, is available at bopcivildefence.govt.nz.