Landslides in New Zealand

Printer-friendly version
Listen: 

Landslides remove material from hills, mountains and coastlines. Landslides are common in New Zealand and can be small events or damaging large events.

Unstable land

New Zealand has a high number of landslides because:

  • land is still being pushed up by plate tectonics
  • rocks are often weak from this movement
  • there are lots of earthquakes
  • the land is hilly and cut by rivers
  • slopes can be unstable, weak layers of volcanic ash or loess
  • rainfall can be high

Some landslides move whole mountain sides, suddenly. Others are small or slow, moving only a few centimetres a year.

Causes

On unstable slopes, three things are important in causing large landslides:

  1. type of land, such as weak rock and steep slopes
  2. processes such as deforestation or stream erosion
  3. large rainstorms and large earthquakes

Human impact

Clearing forest has had the most impact on how stable the land is. Clearing land for farming has increased landslide activity. Building roads and subdivision earthworks can also increase landslide rates.

Types of landslides 

There are different types of landslides. Some are slow moving over many years such as creeping earthflows, while others happen suddenly such as rock avalanches in the mountains.

The most common landslide in New Zealand occurs when the loose rock and soil above bedrock slides. These slides are often seen on steep farmland. Landslides can even happen under the sea and if large enough can start tsunamis.

Cost

Each year millions of dollars is spent clearing slips from roads and railway lines. It is a never-ending task – there are always more floods or earthquakes to come, and there is plenty of rock and soil waiting to fall down.

In general, landslides are more common in New Zealand than many countries because of the steep land, weak layers and high rainfall. However, landslides cause few deaths in New Zealand because there are not many people living in steep, mountain areas.

Ready for a quiz?

activity

Audio Maori keywords: 


  • Samoan keywords

  • Tongan keywords

  • Cook Islands Māori keywords

  • Niuean keywords


You could find out if and where there has been a landslide in your local area and what caused it.

Previous
Earthquakes in New Zealand

Next
Tsunami in New Zealand

Standard

A massive rock avalanche changed the height of New Zealand's highest mountain, Aoraki Mount Cook, in December 1991. Can you find out about other large rock avalanches in New Zealand? Image: Loyd Homer, GNS Science.

Landslides are common in New Zealand. This landslide is in Whakatāne. Can you find out what large landslides there have been in New Zealand recently. Image: LEARNZ.

One of New Zealand's most well known landslides was the 1979 Abbotsford landslide in Dunedin which left 69 houses uninhabitable. What type of landslide was this and was anyone hurt? Image: GNS Science

Landslides are common in areas that have been cleared of trees for farmland, especially after heavy rain. Image: LEARNZ

There are different types of landslides. Sometimes landslides can be a combination of different types. What are the most common landslides in New Zealand? Image: United States Geological Survey. Art work by Margot Johnson.