Landslides can happen without warning. They are often triggered by heavy rain, earthquakes and in some cases, human activity.
Landslides occur when sloping ground becomes unstable and rock, soil or vegetation fall down a slope. Landslides cause more deaths than any other geological hazard in Aotearoa New Zealand. They can cause significant damage to buildings, roads and other infrastructure. They can also dam rivers and if the dam fails, this can result in flooding downstream.
Find out what to do before, during and after a landslide.
Some areas are at a higher risk of landslides – including areas with existing old landslides, steep slopes, drainage channels on steep slopes, stream and riverbanks, or coastal cliffs.
- The best option is not to build or develop on unstable or hazardous/higher risk sites. Seek expert advice from a chartered professional geotechnical engineer if you are planning on excavating or building on steep slopes or believe the site may be affected by landslides. Council Land Use Planning plays an important part in this.
- Be aware that landslides on another property could affect you – for example, if you are in the path of a landslide runout.
- Find out from your council if they have information on landslide hazard and risk, if there have been landslides in your area before, and where they might occur again.
- Areas that are prone to landslide often include existing (old) landslides, steep slopes, streams or riverbanks or coastal cliffs.
- If you have a slope on your property, check drains are clear and adequate, and that retaining walls are in good condition.
- Learn the warning signs for unstable ground:
- Small slips, and rockfalls.
- Subsidence at the bottom of slopes.
- Doors and window frames that start to stick, or gaps developing around them.
- Outside fixtures like steps, decks and verandahs moving or tilting away from your house.
- New cracks or bulges on the ground, road or footpath.
- Trees, retaining walls or fences that start to tilt.
- Be alert when driving, especially where there are embankments along roadsides. Watch the road for collapses, mud and fallen rocks.
- Review your insurance regularly.
Get your household ready. Work out what supplies you might need and make a plan together.
✔️ Make and practise your emergency plan
✔️ Make a grab bag and have emergency supplies in case you need to evacuate
✔️ Know how to stay informed
Regularly inspect your property, especially after long dry spells, earthquakes or heavy rainfall.
- Look for signs of instability: doors and windows that start to stick, gaps appearing, decks moving or tilting away from the house, new cracks or bulges on the ground, leaning trees or fences, slope movement, etc.
- Watch the land around where you live for signs of increased threat. Look at the hillsides around your home for any signs of land movement (like rockfall, small landslides or debris flows) and any trees that start to “tilt” over time.
- Watch the patterns of storm water drainage on slopes near your home, and especially the places where runoff water converges, increasing flow over soil-covered slopes. Noticing small changes can alert you to an increased threat of a landslide.
If you notice any of these changes, seek professional advice as soon as possible. There may be some problems you can fix yourself, but many will require expert help.
Other things you can do:
- Keep gutters, downpipes and drains free of dirt, leaves and other blockages. Trim back or remove vegetation blocking drains and gutters.
- Inspect swimming pools regularly for leaks.
- Regularly empty septic tanks.
- Check retaining wall drainage for blockages and water build-up behind the wall.
- Regularly check and clear drains.
Recognise the warning signs and act quickly
Landslides can occur without any warning signs. Be aware of the potential for landslides, particularly in the weeks after potential triggering events, such as heavy rainfall, earthquakes, and previous landslides. If you see a landslide, move quickly out of its path and stay away from it. It is important to recognise the warning signs and act quickly.
Some warning signs before landslides occur:
- Small slips, rock falls, and sinking land, at the bottom of slopes.
- Sticking doors and window frames, which may mean the land is slowly moving under the house.
- Gaps where window frames are not fitting properly.
- Steps, decks, and verandas, moving or tilting away from the rest of the house.
- New cracks or bulges on the ground, road, footpath, retaining walls and other hard surfaces.
- Tilting trees, retaining walls, or fences.
If you learn or suspect that a landslide is occurring, or is about to occur in your area:
- Evacuate immediately if it is safe to do so. Seek higher ground outside the path of the landslide. Getting out of the path of a landslide or debris flow path is your best protection.
- If you cannot leave safely, move out of the path of the debris. The side of your house furthest from the landslide is likely to be the safest location within the property. Take your pets with you, and move livestock to safe paddocks, if you can do so without endangering yourself.
- Alert your neighbours. They may not be aware of the potential hazard. Advising them of a threat may save their lives. Help neighbours who need assistance to evacuate if you can do so without putting yourself in danger.
- Contact your local council or technical expert. Local council engineers or other geotechnical engineers are the people best able to assess the potential danger.
What to do if a landslide occurs
If you see a landslide, move quickly out of its path and stay away from it.
If lives are in danger, evacuate immediately and dial 111. Alert your neighbours if you can do so safely. If you can’t get outside, move away from the slide area and dial 111. Stay away from the landslide area. Further landslides may occur.
Check for injured and trapped persons and animals near the landslide, without entering the landslide area. Direct rescuers to their locations.
What to do during severe storms
During a severe storm, if you are in an area susceptible to landslides, you should:
- Evacuate if you can - move to higher ground and out of the path of potential landslides. Staying out of the path of a landslide can save your life.
- If you cannot evacuate, move to an upper floor in your whare/home, or the side furthest from the potential slide area. This is likely to be the safest location within the whare/home.
- Stay up-to-date with the latest weather information from MetService, Te Ratonga Tirorangi, New Zealand’s National Weather Service. Pay attention to heavy rain warnings. Short bursts of heavy rain may be particularly dangerous, especially after longer periods of wet weather.
- Watch for signs of slope movement, such as:
- small slips, rock falls, subsidence or bulges at the bottom of slopes
- cracks in the ground, plaster, brick work, tiles, foundations, retaining walls, driveways and other hard surfaces
- tilting trees, walls or fences
- building movement, such as doors or windows that stick or jam
- outside fixtures, such as steps, that are pulling away from buildings.
- If you are near a stream or waterway, be alert to any sudden increase or decrease in water flow, and to a change from clear to muddy water. Such changes may indicate landslide activity upstream, so be prepared to move quickly. Save yourself, not your belongings.
- Be especially alert when driving. Embankments along roadsides are particularly susceptible to landslides. Watch the road for collapsed areas, mud, fallen rocks, and other indications of a possible debris flow.
- Ensure livestock are in safe paddocks if there is heavy rain. Consider precautionary evacuation of livestock if you believe there is a risk of landslide.
Further landslides may occur, so stay away from the affected area.
- Stay away from the landslide area until it has been properly inspected and authorities give the all clear.
- Look for broken utility lines (power, telephone) and report them to appropriate authorities. Reporting potential hazards will get the utilities turned off as quickly as possible, preventing further hazard and injury.
- Help others if you can, especially people who may need extra help.
If your property is damaged:
- Do not do anything that puts your safety at risk or causes more damage to your property.
- Contact your insurance company as soon as possible.
- If you rent your property, contact your landlord and your contents insurance company.
- Take photos of any damage. It will help speed up assessments of your claim.