New Zealanders are not yet in the clear from landslide danger following the week’s severe weather in the upper North Island, the National Emergency Management Agency warns, with experts saying saturated slopes could continue to fail for several days.
Six people remained unaccounted for after a major landslide at a Mount Maunganui campground, including a 15‑year‑old.
Police were also seeking information on three individuals believed to be international tourists who may have since left the area.
In Pāpāmoa, two people have died and another was seriously injured after a separate slip destroyed a home on Thursday.
Emergency services continue to work through hazardous terrain, with access to several affected sites still limited by flooding, debris and unstable ground. Authorities say some areas remain too dangerous to enter, and further slips could hamper search efforts.
Agencies today revealed six people were unaccounted for, the youngest aged 15. (Source: 1News)
NZ's deadliest natural hazards
Landslides have historically been New Zealand’s most deadly hazard, killing more people in the past 200 years than all earthquake disasters combined, said Dr Tom Robinson, senior lecturer at the University of Canterbury.
"As our climate continues to warm, the warmer atmosphere can hold more moisture leading to more frequent and heavier rainfall, which in turn is likely to cause more frequent landslides," he said.
"Unfortunately, this means we should expect these kinds of storm events to become more common over the coming years. The risk from landslides in New Zealand is only likely to increase."
Mitigation options were "often expensive and not always possible”, and avoiding building in high risk areas remained the most effective long term strategy, Robinson said, although this was a challenge for existing properties.
Scientist cautions: 'little slips can turn into a very big one very quickly' - Watch on TVNZ+
University of Auckland applied geology professor Martin Brook said Bay of Plenty, Coromandel, Northland and Tairāwhiti were consistently susceptible to slope failures in heavy rain.
"The water weakens the surface soils and underlying highly weathered rock, causing shallow landslides to occur,” he said.
Brook said this week’s rainfall aligned with the tail end of a La Niña pattern, which generally brought wetter conditions to northern parts of the country.
Scale of Mt Maunganui slip shocks scientist
Geomorphologist Brenda Rosser, leading the scientific response to this week’s landslides, said the large slip at Mount Maunganui was striking in its size.
"I was surprised how big it was… I want to acknowledge the people that have been affected. It's pretty devastating," she said.
Rosser said Tauranga and Bay of Plenty had experienced occasional coastal slips, but historically hadn’t seen large numbers, although the region was “on the radar” as storms intensified.
Landslides were New Zealand’s most common geohazard, occurring more frequently than earthquakes or volcanic events, Rosser said.
In major storms, the numbers can be extreme.
"In Cyclone Gabrielle, we estimate there were upwards of 800,000 landslides triggered by that one event," she said.
During this week’s weather, only slips that hit roads, people or social media were mapped — around 100 so far — although many more were expected in remote areas.
Rosser said small slips could be reduced through land management, such as tree planting, where root systems helped stabilise soil and forest canopies softened rainfall impact.
But large, deep-seated failures, such as those seen during Cyclone Gabrielle or the 2016 Kaikōura earthquake, could not be stopped by surface interventions.
"Once they are initiated, there's nothing we can do about it."
Rosser urged residents near cliffs, escarpments or steep hills to have a plan for heavy rain, know the warning signs, and act quickly.
“If you see a small slip happening, just get prepared to get out of the way,” she said. “Some of those little slips can turn into a very big one very quickly.”
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