Landslide risk explained
Slopes, slips, rockfall, and mapped past landslide events across eight supported cities.
Slope-related hazards differ by region. Councils publish susceptibility modelling, slope management areas, and in Auckland a validated inventory of past landslide events. All are regional desktop data, not site-specific geotechnical assessments. iQHOME checks the layers available for Auckland, Wellington, Christchurch, Hamilton, Tauranga, Rotorua, Dunedin, and Queenstown Lakes. See What iQHOME checks for you for the layers in your city.
Shallow landslide susceptibility
Council mapping combines slope angle, geology, and historical slip patterns to flag areas where shallow landslides are more likely during heavy rain or after ground disturbance. This includes hillsides, steep driveways, cut slopes behind houses, and sections near cliffs or gullies.
In Auckland, the shallow landslide layer is refreshed weekly from council sources. Wellington uses Greater Wellington Regional Council mapping for the same hazard type. Susceptibility is shown in bands from very low through to very high. A result at your pin means the mapping applies directly to the property location; nearby means susceptibility is mapped within about 200 metres.
Large-scale landslide susceptibility
Auckland Council also publishes large-scale (deep-seated) landslide susceptibility mapping. This is separate from shallow landslide susceptibility and covers bigger, regional slope failures that can affect extensive hillside or bush areas, not just surface slips after heavy rain.
Large-scale mapping is most relevant on steep Waitākere Ranges terrain, bush-clad hillsides, and other areas where deep-seated movement has been modelled regionally. On an iQHOME report, susceptibility bands run from very low through to very high, the same broad categories as the shallow layer, but they describe a different type of hazard.
If both shallow and large-scale layers appear on a report, read them together: shallow mapping flags rain-triggered surface slips, while large-scale mapping flags deeper regional instability. Neither layer replaces a geotechnical report for a specific building platform, retaining wall, or excavation. Treat high or very high results as a serious flag and confirm with council records and qualified professionals before you buy, build, or remove vegetation.
Slope and rockfall hazard
Christchurch City Council publishes slope instability and rockfall management areas across the Port Hills and other steep terrain. If your pin intersects these zones, retaining walls, rockfall protection, insurance, and building rules may need closer review.
Earthquake-induced slope failure potential
Separate from shallow rain-triggered slips, this layer models how severely slopes may fail during earthquake shaking. It is most relevant on steep Wellington hillsides and cliff-top sites where ground movement could affect buildings or access.
Landslide inventory (mapped past events)
Separate from susceptibility modelling, Auckland Council publishes a validated landslide inventory of documented past events. This shows where landslides, debris areas, source areas, damaged structures, hummocky ground, or gully erosion have already been mapped. This is not where a slip might happen in future, but where one already has.
On an iQHOME report, inventory polygons appear alongside shallow and large-scale susceptibility layers. A hit means your pin intersects a mapped past event feature. Nearby means inventory mapping lies within about 200 metres. Treat any inventory hit as a strong flag to review council records and geotechnical advice before you buy, build, or remove vegetation on steep ground.
Slope hazard zones
Tauranga City Council publishes slope hazard zones including failure, regression, and runout areas on steep development land. Relevant for hillside sections and elevated sites around the harbour and hinterland.
Landslide susceptibility
Rotorua Lakes Council maps landslide susceptibility in bands from very low through very high, similar to Auckland's shallow layer. Most relevant on lakeside cliffs, geothermal margins, and steep volcanic terrain.
Land instability (2GP)
Dunedin City Council maps land instability under the district plan (2GP). This flags hillsides and coastal slopes where instability has been identified for planning purposes, including parts of the Otago Peninsula and harbour slopes.
Landslide areas
Queenstown Lakes District Council publishes detailed landslide areas mapping including debris flows, rockfall, shallow slips, and slope failures in schist terrain. Essential reading for alpine, lakeside, and steep Wakatipu / Wanaka sections.
A hazard at your pin means the mapping intersects the property location. Nearby means susceptibility is mapped close to the pin, for example on a slope or cliff behind the house. Both are worth understanding, but they mean different things for the building itself.
- Retaining walls, drainage, and insurance can cost more on slip-prone sites
- Recent storms and earthquakes have increased awareness of hillside failure
- Building and earthworks rules may be stricter in mapped areas
If landslide or slope mapping appears on a report, consider a geotechnical assessment before you buy, especially if you plan to build, excavate, or remove vegetation. Confirm LIM and council records with your lawyer and the appropriate council.