Advice for homeowners

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Is your home at risk?

Accurately predicting future landslides is not yet practical. However, there are some steps you can take to help identify landslides:

Look for indications around the site
Check with the Natural Hazards Commission
Check with your local council
Check online landslides databases
If in doubt, get advice from a geoprofessional

1. Look for indications around the site

These are some common indications of land instability:

Pavements sinking or finding new rocks, soil, or other debris on or around your house and property.
Changes in your landscape such as patterns of storm-water drainage on slopes (especially the places where runoff water converges) land movement, small slides, flows, or progressively leaning trees.
Doors or windows stick or jam for the first time.
New cracks appear in plaster, tile, brick, or foundations.
Outside walls, walks, or stairs begin pulling away from the building.
Slowly developing, widening cracks appear on the ground or on paved areas such as streets or driveways (these can also be caused by seasonal wetting and drying of soils)
Underground utility lines break.
Bulging ground appears at the base of a slope.
Water breaks through the ground surface in new locations.
Fences, retaining walls, utility poles, or trees tilt or move.

2. Check with the Natural Hazards Commission

Check that there haven’t been any historical claims made to the Natural Hazards Commission Toka Tū Ake for the home, or neighbouring properties. You can see these on a map here, and find out more from the Natural Hazards Commission here.

3. Check with your local council

Most councils have a set of planning maps that show areas that might be at risk of natural hazards, and sometimes these include landslides. These are often not detailed enough to be reliable to give a precise answer for a single house. You can read more about these maps here.

Past landslides are a good indication of the risk, so you can sometimes find out if your property is at risk by contacting your local council to see if there are historical landslides on or near your property. Councils maintain some records, but they’re rarely complete because council’s are often not informed about landslides. You’re just as likely to identify the warning signs yourself.

4. Check online landslide databases

Past landslides are a good indication of the risk, so you can sometimes find out if your property is at risk by looking at records of old landslides. Common resources are:

Look for recorded landslides near your property. Bear in mind that none of these records are complete as there’s not always an obligation for landslides to be reported.

5. Get advice

If in any doubt get advice from a geoprofessional.

Before a landslide occurs

If you know your land is unstable, there are a number of things you can do to prevent slips occurring.

Get advice

While the ideas below give a useful starting point, it’s essential that if you have concerns that you contact a local engineering consultancy to provide advice. Ask for a Professional Engineering Geologist or Geotechnical Engineer. They are trained to recognise signs of serious problems that you might not see – a quick site inspection could save your house. Find out more here.

Control the water

Many landslides are triggered by excess water, either flowing over the surface or in the soil. Make sure that storm water from your property doesn’t discharge or overflow towards any unstable land. Check your pipes, irrigation systems or stormwater soakage.

If stormwater does flow over the slope, try to direct it away from the least stable areas, and avoid it soaking in through cracks by filling them with clay. Be wary of digging drainage swales which may control the flow direction but could encourage water to soak in, and may form a line of weakness.

If a landslide has occurred, cover bare surfaces and cracks in the ground with tarpaulins to reduce the impact of rain. Take care – only do this if you can do it safely. Avoid if it’s still raining.

Reduce the load

If the slip has a heavy load at the top, it’s more likely to fail. Keep heavy mobile objects (such as cars) away from the top of unstable slopes.

Do some planting

Plants can be very effective at sucking the excess moisture out of a slope, adding to the stability, and reinforcing the slope with their roots. This useful guide gives suggestions for suitable species in coastal environments, and more general landslide planting guidance (mostly appropriate to North Island conditions) is at the bottom of this page.

If a landslide happens

Responsibilities for helping out in a landslide depends on a number of factors. This page should help you find the right advice.

Immediately after the landslide occurs

If a building or public road is at imminent risk…

In the event of an imminent or actual landslide where lives are in danger, evacuate, warn your neighbours, then dial 111.
If a road is at risk, or is blocked, dial 111. If you are confident that it is a low risk, contact your local council instead.
If there is property damage (i.e. damage to buildings, not land) but no injuries call your local council Building Compliance team to assess if the buildings are safe to occupy. Normally a phone call is the best way to get a quick response. They can normally visit at short notice. You can find the contact number for your council here.
Stay away until authorities give the all-clear, as further landslides are likely. Landslides can occur progressively, often some time (hours or days) after a the first movement. Be aware of any changes to your property/ground following a landslide or major rainstorm/earthquake. In particular you should look for new cracks or ground bulging.
Check for injured and trapped persons and animals near the landslide, without entering the landslide area. Direct rescuers to their locations.
Report broken utilities (water, gas, electricity) to the appropriate companies. Reporting potential hazards will get the utilities turned off as quickly as possible, preventing further damage or injury.
If you can do it safely, take photographs of the damage – this may help with an insurance claim later.
Report the landslide here.

If no homes or roads are at immediate risk…

If there is private land damage but no immediate risk, contact a local engineering consultancy to provide advice. Ask for a Professional Engineering Geologist (with PEngGeol registration) or Geotechnical Engineer (with CPEng registration).
Report the landslide here
If their is public land damage but no immediate risk, contact your local council call centre.

If council land (e.g. a park or reserve) is affecting your land…

Report the landslide here
Contact your local council call centre.
Note that while adjacent landowners have some responsibility to keep their land in reasonable condition, they aren’t automatically obliged to prevent landslides, or to repair landslides caused by natural events. You may need to work with them to get a mutually acceptable outcome.

If a waterway is blocked…

Report the slip here
Contact your local council call centre.
Remember that most streams are privately owned, and it is the responsibility of the owner to keep them clear, so you may need to get a contractor to help you.

Making it safe

If you need to urgently protect your land from further failures, it’s often best to take some quick actions to prevent the situation deteriorating or becoming unsafe. This may mean spending money before you know if any insurance claim is successful. If you do this, it is at your own risk, so take care.

Remember that your life is more important that your property, so stay well away from unstable land.

Divert water away from the landslide. This may include laying sandbags to intercept rainwater runoff, or diverting damaged pipes – you may need to engage a plumber or drainlayer to help.
Move any heavy loads away from the crest of the slope (eg parked cars)
Drape plastic sheeting over the slip from the crest to stop rain soaking into the slip or eroding the surface. Tie it in well at the top so that water running over the ground doesn’t run under the sheets.
Put barriers in place if there’s any risk of people getting too close.

Get professional advice

Once these are in place, get professional advice.

You can also get some useful advice from the Ministry of Business, Innovation and Employment here.

Getting it fixed

Who is responsible?

In general the owner of the land is responsible for their land. However, this doesn’t mean that a neighbour has to repair a landslide to protect your home. If your neighbours land has moved and caused damage, they don’t automatically have an obligation to repair it, even if it affects you, unless they caused the slip by their own negligence. Each case has it’s own circumstances, so there’s no fixed rule.

All landowners have a general duty of care to act reasonably to prevent or mitigate damage to a neighbour’s property due to a hazard on their land once they are aware of it – so if you have concerns about a neighbouring property, you get professional advice and should inform them in writing.

This summary from a High Court case may help explain the legal situation where a landslide crosses a property boundary.

Inform your insurer

If your house or land is damaged, you may be able to make a claim with your insurance company or NHC. You can find out more about what’s covered here. NHC have a set of rules and criteria, so you will need to lodge a claim with them to find out if you’re covered.

Get advice

Contact a local engineering consultancy to provide advice. If you have insurance, and the claim is valid, they should arrange this for you. Find out more here.

Detailed advice from MBIE

You can find out more here: https://www.building.govt.nz/assets/Uploads/managing-buildings/slope-stability-quick-guide.pdf

Planting to stabilise slopes

As long as a landslide doesn’t imminently threaten a house or other critical assets, one of the easiest and sometimes most effective ways to prevent a landslide getting worse is to re-plant it. The guide below gives a useful starting point. The recommendations are focused on Auckland, so speak to your local garden centre for advice about which species might suit your climate in other regions.

slip-remediation-guidance_planting-advice-2_april2023 Download

Getting professional advice

If you’re looking for a professional to help solve a geotechnical problem it is important that you use appropriately qualified geotechnical professionals. You’ll need either a Chartered Professional Engineer who specialises in geotechnical engineering, or a Professional Engineering Geologist. Look for the qualifications CPEng (Geotechnical) or PEngGeol. These are the quality marks administered by Engineering New Zealand, and the holders of these certifications are held to a high standard of professionalism and follow the Engineers New Zealand Code of Ethical Conduct, available here.

Large consulting engineering firms might not work for private residential property owner because of concerns about the unlimited warranty associated with the Consumer Guarantees Act. Many small to medium firms are technically capable and are more comfortable working in the space.

Do I need a Geotechnical Engineer (CPEng Geotechnical) or Engineering Geologist (PEngGeol)?

Engineering Geology is the profession responsible for defining the geotechnical problem, and identifying and characterising the hazards and material properties. Geotechnical Engineers then take this information to design the appropriate solution. These two functions work together to ensure a safe design. If you’re not sure which you need, ask a professional. You can check if the person you’re getting advice from is suitably qualified by checking the list here – you can search for them by name.

Geotechnical engineers should have “Geotechnical engineering” in their Practice Field and should have “CPEng” as their post-nominal.
Engineering geologists should have “PEngGeol” as their Membership.

Not everyone that works on your project needs to be registered, but you should insist that the person responsible for signing any formal documentation is on one of these two registers to protect your interests.