Mt Maunganui landslide: Council report warned slopes primed to fail
Friday, 23 January 2026
A July 2025 landslide study clearly flagged the danger across Mount Maunganui, using the volcanic peak as a case study to assess slope instability.
But the deadly slip this week, which buried at least six people, struck just outside the hazard zones officials had mapped.
Early warning signs came hours before the catastrophic 9.30 am slip, including a smaller slide around 5 am that prompted a camper to wake others at the Beachside Holiday Park. Questions are now swirling over why the area was not evacuated, with Tauranga Mayor Mahé Drysdale promising a full review of the response.
Last year’s report, commissioned by Tauranga City Council, clearly identified the volcanic peak as prone to landslides, using high-resolution terrain mapping to define high-risk slopes.
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However, the study area stopped at Adams Avenue, just east of the Beachside Holiday Park, leaving the zone where Thursday’s slip struck outside official hazard boundaries.
The combination of steep terrain and unstable soils in the region has created ongoing landslide risk for more than a century.
The city has recorded documented landslide damage since 1907, with major events triggered by storms in March 1979, May 1995, May 2005, April 2017, and January 2023.
A 2014 scientific paper by researchers in New Zealand and Canada included a graphic map showing the locations of all landslides on Mauao dating back to 1943, highlighting a massive slip in 1977 behind the campground and hot pools — the same area where Thursday’s catastrophic slide came down.
That history of instability prompted the council to launch a city-wide landslide mapping project in 2023.
Despite being off the study map, Mauao was the primary case study used to determine the risk levels for the rest of the area in the July 2025 report, written by consultants WSP.
Experts spoken to by The Post suggest it was left off the map because there are no permanent properties on the slopes requiring LIM notices, but leaving tourists and short-term visitors exposed to risk.
The authors highlighted rainfall as the primary trigger for landslides, noting that heavy storms can cause shallow slides on volcanic slopes.
They cited 2011’s ex-Cyclone Wilma, when intense rainfall triggered at least eight large landslides on Mauao. (An April 2017 slip, that took out the popular base track during ex-Cyclone Debbie is not referenced).
Debris flows were made up of “rhyolitic material and colluvium” – a destructive mix of volcanic rock fragments and loose soil.
The report also reduced safety buffers across Mount Maunganui and Pāpāmoa, shrinking runout zones (where landslide debris will travel after a slope fails).
WSP told The Post the council would not allow the report’s authors to speak with media. The council did not respond to questions on Friday night.
Tom Robinson, senior lecturer at the School of Earth and Environment, University of Canterbury, and an expert in disaster risk and resilience, explained the challenge for councils in areas like Mount Maunganui.
“It’s probably one of the more difficult tasks we have… to forecast when a landslide is going to occur, exactly where it’s going to occur, and then where it’s going to go. All three of those things are very, very, very difficult.”
He highlighted how nearly identical slopes can behave differently: “From [Cyclone] Gabrielle slopes that look absolutely identical, experiencing exactly the same amount of rainfall, one fails and one doesn’t. The runout is a few tens of meters on one, and hundreds on another.”
As climate changes increase, intense rainstorms and landslides are going to become more common. But Robinson emphasised the challenge of relying on historic hazard mapping in a changing climate. “Even areas that have never failed before could become vulnerable because a small amount of rain can push a slope over the edge.”
He noted that mapping studies are often based on historical rainfall patterns and observed failures – meaning that new extreme events can quickly exceed the assumptions those maps rely on. “What was considered a safe zone a few years ago might no longer be safe under current or future climate conditions,” Robinson said.
Robinson also put the human cost in perspective. “Since European settlement, landslides have killed around 1800 people in New Zealand – more than all earthquakes combined. We tend to focus on big events, but it’s these smaller, deadly slips that take lives one or two at a time, often in places people think are safe.”