Landslides (ground slides, debris flows, rockfalls) occur when soil or rock on slopes moves under gravity. Causes include intense rainfall, earthquakes, steep terrain, rising groundwater, and artificial slope modification.
Intense rainfall is the most common landslide trigger. As rain infiltrates soil, friction between soil particles decreases and slopes become unstable. Earthquakes similarly disturb bedrock and destabilize slopes.
Mountainous regions, especially those with steep terrain, have high landslide risk. Deforestation and mountain development lower slope stability. Countries like Indonesia, Philippines, Japan, and Mexico with heavy rainfall and mountainous terrain face especially dangerous landslides.
Personal risk management includes checking historical landslide maps, avoiding slope properties, and improving drainage if living on or below slopes.