Landslides, rockfalls, debris flows

The rise in the permafrost base (by 100-250 metres since 1850) increases the risk of landslides, rockfalls, and debris flows, since the loose material and rocks held in place by the permafrost may become detached in a thaw.

Examples here include the rockfall on the Matterhorn in the summer of 2003 and the Kolka-Karmadon (Caucasus) catastrophe on 20 September 2002, when a huge landslide tore off a glacier tongue, triggering an avalanche of rock and ice (volume: approx. 80 million m³) and claiming 120 lives.

Great ice avalanches may also occur, however, if a glacier retreats into steeper terrain, and the glacier tongue threatens to break off due to gravity.