Landslides

A landslide is the movement of rock and soil down a slope. Landslides range in size from a single boulder in a rock fall to a debris avalanche, which may have huge volumes of rock and soil capable of covering many kilometres.

Heavy rain, floods, or earthquake shaking can cause landslides. They can also be caused or made worse by human activity - such as removal of trees and plants, steep roadside cuttings or leaking water pipes.

The Wellington region has a rugged landscape with numerous houses built on landslide-prone hillsides. Many roads are cut into slopes or pass through steep gorges and are vulnerable to surface slips or larger landslides.

A storm in 1976 caused widespread landslides in Wellington City and the Hutt Valley. One landslide took out 3 houses in Ngahere St, Stokes Valley.

An old landslide triggered by the 1855 Wairarapa earthquake can be seen on the western side of the Hutt motorway, just north of the BP service station. The 1855 earthquake also triggered a very large landslide that temporarily blocked the Ruamahanga River and formed the Hidden Lakes at Kopuaranga, north of Masterton.