Landslides – New Zealand’s deadliest natural hazard
In January 2026 a series of storms brought severe weather to the upper North Island of Aotearoa New Zealand. The intense rainfall caused a number of major landslides with devastating results. Landslides can happen without warning. They are often triggered by heavy rain, earthquakes and, in some cases, human activity.
This article has been republished from The Conversation under Creative Commons licence CC BY-ND 4.0 and was written by Martin Brook, Professor of Applied Geology, University of Auckland, Waipapa Taumata Rau. This article was originally titled: The Mount Maunganui tragedy reminds us landslides are NZ’s deadliest natural hazard.
January 2026 tragedy
The tragic events in the Bay of Plenty this week [26 January 2026] are a stark reminder that landslides remain the deadliest of the many natural hazards New Zealand faces.
On Thursday morning, a large landslide swept through the Mount Maunganui Beachside Holiday Park at the base of Mauao, triggering a major rescue and recovery operation that will continue through the weekend.
Landslide damage on Pāpāmoa hills
In January 2026 severe weather caused multiple destructive landslides. One area significantly impacted was Pāpāmoa, where two people died after a landslip hit a house.
Hours earlier, two people were killed when a separate landslide struck a home in the Tauranga suburb of Welcome Bay. As of Friday evening, six people remain missing at Mount Maunganui. [Their bodies were subsequently recovered.]
These events occurred at the tail end of a weak La Niña cycle, which typically brings wetter conditions to northern New Zealand. At the same time, unusually warm sea-surface temperatures have been loading the atmosphere with extra moisture, helping to fuel heavier downpours.
In parts of northern New Zealand, more than 200 millimetres of rain fell within 24 hours in the lead-up to last week’s events – well above the typical thresholds known to trigger landslides.
Regions such as the Bay of Plenty, Coromandel, Northland and Tairāwhiti are especially vulnerable to intense rainfall, which weakens surface soils and the highly weathered rock beneath them, allowing shallow landslides to detach and flow downslope.
Landslide warning
The National Emergency Management Agency is the New Zealand’s Government’s lead for emergency management. It issues warnings (sometimes under New Zealand Civil Defence) on various social media channels. For example, this one from Facebook: “Landslides can happen without warning...”.
Most landslides in New Zealand are triggered by heavy rainfall, through a complex interplay of intrinsic factors – such as slope angle, soil and rock strength, and vegetation cover – and extrinsic factors, including rainfall intensity and how wet the ground already is from prior rainfall when a storm arrives.
Much of this risk is invisible, accumulating quietly beneath the surface until a sudden collapse occurs.
This helps explain why landslides have long proved so dangerous. Since written records began in 1843, they have been responsible for more deaths than earthquakes and volcanic eruptions combined.
Much of New Zealand’s steep, geologically young landscape is pockmarked by the evidence of millions of past landslides, most occurring on pasture and remote areas, far from people.
When landscapes tell a story
At Mount Maunganui, the shape of the land itself tells a story. The surrounding hill slopes are riddled with the scars of past landslides, revealing a landscape that has been repeatedly reshaped by slope failure over time.
New high-resolution mapping now allows scientists to see this in unprecedented detail. A 2024 LiDAR-derived digital elevation model, which effectively strips away vegetation to reveal the bare land surface, shows numerous landslide features across the slopes.
Many cluster along the coastal cliffs, but two particularly large ancient landslides can be seen directly above the holiday park.
High-resolution elevation map of Mount Maunganui
A high-resolution elevation map of Mauao and surrounding land at Mount Maunganui, drawn from Land Information New Zealand data, showing landslide features. Two ancient landslides, or paleolandslides, above the campground site are labelled L1 and L2.
These older slips left behind prominent head scarps – steep, crescent-shaped breaks in the hillside – indicating where large volumes of material once detached and flowed downslope onto flatter ground below.
Subsurface evidence reinforces this picture. A geotechnical investigation carried out in 2000, near the northern end of the campground’s toilet block, found a 0.7 metre layer of colluvium – loose debris deposited by earlier landslides and erosion – buried beneath the surface.
In other words, the site itself sits atop the remnants of past slope failures.
Mauao landslide slope analysis
This image provides two views of the slopes above the campground at Mauao (Mount Maunganui). On the left (A) is a 2023 aerial photo showing the steep hillside and the location of earlier ground testing. On the right (B) is a detailed elevation map revealing two ancient landslides (L1 and L2) hidden in the landscape. The star marks the approximate starting point of the 22 January 2026 landslide.
The January 22 landslide appears to have initiated in the narrow zone between the two earlier slips. This is a particularly vulnerable position: when neighbouring landslides occur, the remaining wedge of land between them can lose lateral support, becoming unstable, like a rocky headland jutting out from a cliff face.
Over long timescales, this kind of progressive slope collapse is a normal part of landscape evolution. But when it unfolds in populated areas, it can turn an ancient geological process into a human disaster.
From prediction to prevention
Predicting how far a landslide will travel, and which areas it might inundate, is critically important – but it remains an inexact science.
At its simplest, this can involve rough rules of thumb that estimate how far a landslide is likely to run based on slope height and angle. More sophisticated approaches use advanced computer models, such as Rapid Mass Movement Simulation (RAMMS) which simulate how landslide material might flow across the landscape.
These models were used, for example, to assess landslide risk at Muriwai, Auckland, following Cyclone Gabrielle.
By adjusting inputs such as rainfall intensity and soil properties, scientists can explore a range of possible scenarios, generating estimates of how far future landslides could travel, how deep the debris might be, and which properties could be affected.
The results can then be translated into landslide hazard maps, showing areas of higher and lower risk under different rainfall conditions. These maps are not predictions of exactly what will happen, but they provide crucial guidance for land-use planning, emergency management and public awareness.
New Zealand has made major progress in mapping floodplains, and most councils now provide publicly accessible flood hazard maps that influence building rules and help communities understand their exposure.
In the future, developing similarly detailed and widely available maps for landslide hazards would be a logical – potentially life-saving – next step.
Related content
Discover more about extreme weather and cyclones, typhoons and hurricanes.
Land-use decisions and extreme weather examines the consequences of land-use and management decisions in Aotearoa.
Evidence of climate change in Aotearoa notes further examples of extreme weather events.
Ice melt in Greenland and Antarctica predicted to bring more frequent extreme weather is another article from The Conversation.
The articles Sensing the Earth and Satellite sensing look at how satellites sensors are used to gather data for a wide range of purposes, including storm damage.
For more on landslides, see our Pinterest board.
Activity ideas
Use the Home disaster kit activity to help prepare for an emergency.
Discover how scientists and others help us stay safe in Who's on your team?
Useful links
Find out more about some of the research and resources mentioned in this article:
The Conversation hosts a range of articles under their Landslides topic.
On the Australian Bureau of Meteorology Southern Hemisphere Monitoring page there is information on the broader hemispheric climate state, including the status of the El Niño–Southern Oscillation and the Indian Ocean Dipole.
Sea surface temperatures are a key influence on weather and climate. Record ocean heat in the summer of 2025/2026 was a factor causing Aotearoa’s very wet summer.
The Natural Hazards Portal is a tool for exploring Aotearoa New Zealand’s natural hazard risk. It provides information on natural hazard risk, and what to do about it including landslides.
This Brief report of fatal rainfall‑triggered landslides from record‑breaking 2023 storms in Auckland, written in 2023, helps explain why landslides have long proved dangerous.
High-resolution mapping from Land Information New Zealand (LINZ) National Elevation Programme provides open source LiDAR based elevation data for most of New Zealand. The 3D representations of environments allow scientists to see previously hidden details.
Advanced computer models, such as Rapid Mass Movement Simulation (RAMMS) can simulate how landslide material might flow across the landscape.
The RAMMS models were used by the authors in this 2024 article in the New Zealand Journal of Geology and Geophysics: Landslide hazard and loss-of-life risk assessment for Muriwai, New Zealand following Cyclone Gabrielle in February 2023.
Additional links
Professor Brooks wrote a follow up article for The Conversation Do trees prevent landslides? What science says about roots, rainfall and stability. This looks at how landslides typically reflect a complex combination of factors – from geology and long-term slope evolution to weather, climate and land use.
This interactive map from Dragonfly Data Science, reveals more than 11,000 slips caused by storm.
Download the Landslides Pukapuka PDF in the resources section of Hono – The Māori Emergency Management Network.
Explore information and research into geological hazards from Earth Sciences New Zealand, including a section on landslides.
The National Emergency Management Agency is the New Zealand’s Government’s lead for emergency management.
Find out what to do before, during and after a landslide emergency on the Get Ready website.
This Wikipedia article has information about the January 2026 storms in Aotearoa.
Acknowledgements
This article was written by Martin Brook, Professor of Applied Geology, University of Auckland, Waipapa Taumata Rau. The article was originally published in The Conversation on 23 January 2026. Read the original article.
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