Landslides are common in Iceland, presumably due to the physical characteristics of the terrain and the natural environment. Key contributing factors are the interactions between climate, the lithology of the region, soil erosion, and soils on hills and mountain slopes.
Landslides can transport soil, scree, or even chunks of the bedrock down a slope. Landslides occur for various reasons. Intense rainfall or rapid melt of the snow pack can trigger landslides. Other potential triggers include frost action and frost-weathering, melting and retreat of the permafrost, changes to groundwater currents, seismic activity, and undercutting of mountain slopes by ocean waves or glaciers. Landslides can even be caused simply by the effects of gravity. In Iceland, the highest landslide risk occurs in connection with the low-pressure systems that pass through Iceland from around August to November, bringing high winds and heavy rain, and the spring snowmelt in May and June.
The most common types of landslides in Iceland are rockfalls, mud or debris flows, earthflows, rock falls, rockslides, and gradual creep.
Rockslides are the largest and most dangerous form of landslides. Icelandic geologists have used the term berghlaup to describe a major rockslide event occurring in bedrock. Most of these massive rockslides likely occurred in the early Holocene, shortly after the retreat of the Ice-Age glaciers that covered Iceland. At the time, Iceland was uninhabited. Landslides occur in all regions of Iceland, but they are most common in Central North Iceland (the Skagafjörður region), the Eastfjords, and the Westfjords. The highest landslide risk occurs in connection with the low-pressure systems that pass through Iceland from around August to November, bringing high winds and heavy rain, and the spring snowmelt in May and June.
Landslides and other mass wasting events have caused great loss of life, serious accidents, and enormous economic damage from the time of Iceland’s settlement to the present day, see Avalanches and landslides.