Massive landslide at the San Fernando crater of Nicaragua's Masaya volcano © Flickr/Ben Beiske 

Landslides and mudslides occur when heavy rain, rapid snow or ice melt or an overflowing crater lake sends large amounts of earth, rock, sand or mud flowing swiftly down hill and mountain slopes. Earthquakes, volcanic eruptions, heavy rain storms, and cyclones can trigger landslides. Land-use intensification and climate change are increasing landsliding in mountainous regions.

Shallow landslides typically have little impact on trees. Deep landslides, triggered by major earthquakes or volcanic activity, however can denude hundreds or even thousands of square kilometres of land. In such major landslides, all of the soil down to bedrock is carried downslope, taking all of the trees and other vegetation with it.

Because no soil is left for new plants to grow on, the bare tracks of landslides can remain visible for hundreds of years. Shallow landslides can be prevented by tree cover whereas deep landslides can not be prevented, even with high forest cover.