A landslide is the movement of rock and/or soil, down a slope. Landslides can vary from one or two boulders to massive hillside failures covering many square kilometres. The different types of landslides include rock falls, avalanches, mud flows, debris flow and slope failures. They are a naturally occurring phenomenon and can be caused by natural events including storms with heavy rain, or earthquakes. Landslides can be made worse, or triggered, by human activities including vegetation removal, leaking pipes or earthworks.
Effects of landslide
Small slips after heavy rain are common and may impact their immediate surroundings, such as paths, roads and even houses. Larger landslides, such as the 2003 Paekakariki landslide may cause extensive damage to roads, buildings and other infrastructure, and may block access to or from parts of the region.
Warning signs of a landslide can include:
- Small slips, rock falls and subsidence at the bottom of slopes.
- Sticking doors and window frames.
- Gaps where frames are not fitting properly.
- Outside fixtures such as steps, decks, and verandahs 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.
Risk of landslide
Landslides will most often happen at or near the site of previous landslides. If these are identified, development can be restricted on the site or engineering solutions can be put in place.
Wellington region’s rugged landscape and climate make it prone to landslides.