Landslides, landslips or just "slips"; whatever you call them, New Zealand has lots of them!

If a landslide happens on your property, your first concern should be your own safety and the safety of others at the site.

1. In the event of a landslip where lives are in danger, evacuate, warn other people, then dial 111.
2. Stay away until authorities give the all-clear. Landslides are often active for hours, or days after the initial slip.
3. Check for injured and trapped people, without entering the landslide area.
4. Report broken utilities (water, gas, electricity) to the appropriate companies.
5. Be aware of any changes to the ground after a  major rainstorm or earthquake. Specifically, look for ground cracks or ground bulging.
6. Put barriers in place if there’s any risk of people getting too close (danger tape, if you have it!)
7. Safely, take photographs of the damage and lodge a claim with EQC by phone (0800 326 243) or online here. 

Preventing further damage

When it's safe to do so you can try to prevent any further damage:

• Move any heavy loads (cars, firewood piles, etc) away from the area above the landslip if you can
• Divert water flowing towards the slip.
  • • You could use sandbags or dig shallow trenches to intercept rainwater runoff 
    • Divert damaged pipes or extend these to below the landslip
• Drape plastic sheeting over the slip from the crest to stop rain soaking into the slip or eroding the surface. 

Once these are in place, contact a local engineering consultancy to provide advice on the next steps.  Ask for a Suitably Qualified Person such as an Engineering Geologist or Geotechnical Engineer.

Other things you can do yourself

When the landslip is safe:

• Remove any loose material from the headscarp area by hand (the top of the landslip)
• If ground cracks are present above the landslip these can be filled with clay (usually from the debris)
• Take care when removing debris that you do not destabilise any more ground (particularly if using a digger) 
• Replant the exposed ground with native seedlings to help stabilise the ground and prevent erosion

IMPORTANT: Retaining walls designed to stop any further landslip motion should be designed by a Chartered Engineer and a Building Consent granted by a District Council before construction begins.  

It's not possible to accurately predict landslides, but there are ways to identify and reduce landslide risk at your property:

Have a look around and identify the risks:

• Look up:
  • • Are there cliffs above your property? If so you may be at risk of rockfall.
    • Is there steep ground (particularly fill slopes, gullies and exposed soils) above your property? If so, you may be at risk from debris flows.
    • Are there old or damaged retaining walls above your property? Talk to your neighbours if you are concerned about these.
• Look down:
  • • Is your property supported by fit-for-purpose retaining walls?
    • Does your stormwater discharge onto an unprotected slope? Poorly managed stormwater is a very common cause of landslips in NZ.
    • Is the slope below your property artificially steepened, or modified? This can cause instability if not done sensibly
    • Is there a creek or river below your property that could cause erosion of the slope?
• Look around:
  • • Look for damaged or poorly built retaining walls around your property. Failed retaining structures are a very common cause of landslips in NZ. 
    • Look for blocked or poorly maintained drainage ditches or stormwater pipes. Point-loading of water onto a steep slope is a very common cause of landslides in NZ.
    • Look for evidence of creep (this can eventually lead to more catastrophic failure):
      • • Cracks or bulges in the ground.
        • Deformed fences or buildings.
        • Settled foundations.
        • Cracks in steep driveways.
• Check with your local Council to find out if there is a history of landslips in the area.
• Check the GNS landslide database for local historical landslip information 

Reducing the risk of landslips

There are two broad categories for risk reduction: Reduce the likelihood of the event happening, or reduce the consequences if it does occur.

Ideally, you'll prevent landslips from happening by:

• Ensuring that retaining structures are fit-for-purpose.
• Maintaining or installing effective drainage to avoid point-loading of storm-water onto a slope.
• Replanting cleared slopes with native vegetation (even just throwing collected flax seeds will help). Coastal area planting info is here. Forest replanting info is here.
• Constructing retaining walls (expensive option, but sometimes the best option). Get a Chartered Engineer for this.
• Avoid making steep cuts into a slope
• Avoid creating large fill slopes when excavating 
• Avoid placing heavy loads onto a slope (vehicles, firewood piles, water tanks, etc.) 
• Protect river or stream banks from erosion

Or, you can reduce the consequences by: 

Rock fall from above:

• Plant fast growing trees between the rockfall source area and your property to act as a barrier to rockfall.
• Construct engineered rockfall barriers, or "catch fences".
• Construct earth bunds 

Debris flows from above:

• Construct deflection fences to channel debris away from your house.
• Construct diversion ditches to channel debris away from your house.

If you're still concerned about the risk of landslips at your property, make an evacuation plan or consider moving to a safer location.

IMPORTANT: Retaining walls designed to prevent landslips  should be designed by a Chartered Engineer and a Building Consent granted by a District Council before construction begins.