These three phenomena are being discussed together because these are basically the hazards of mountain areas. Furthermore, rainfall (or snowfall) plays a crucial role although man-made causes increase these hazards to a very large extent.
Landslides are in fact downslide movement of soil and rock under the influence of gravity. Erosion due to rainfall and floods, or excess loading due to heavy snowfall, or weakening of ground due to stream erosion, mining quarrying, or earthquake tremors create landslides. In case of avalanches, snow loading and strong winds are the basic causes. Lack of rainfall and the resulting dryness over large forest areas sustain forest fires triggered by natural causes such as lightning strike or friction, or by man-made causes such as a burning matchstick or cigarette. Strong winds fan the forest fire and spread it.
While rain, snow, dryness and winds are predictable, factors such as erosion, excess loading and man-made causes are not predictable. Thus, the overall predictability of disasters such as landslides, avalanches and forest fires is less as compared to floods and droughts.