In considering the effects and impacts of landslides and snow avalanches, the following special features of these hazards should be kept in mind.
(a) These disasters occur in remote mountain areas with difficult terrain and adverse weather conditions.
(b) The communities (villages and hamlets) are small entities with weak housing, makeshift structures and poor resources.
(c) Landslides and snow avalanches give almost no notice in most cases and enormous amount of rock, soil or snow come crashing with fantastic speed on the often-unprepared communities.
In the light of the above three considerations, the effects and impacts of landslides and snow avalanches may be divided into:
i) Direct effects-physical damage
Anything in the top of a landslide or in its path or at its bottom will suffer severe damage. The same is the case with a snow avalanche when anything in its path or falling areas will suffer severe damage. In case of a snow avalanche of “slab type” where massive slabs of hardened snow come hurtling down, the hit is very hard and devastating where as the “loose snow’ type of snow avalanche may engulf and cover larger area.
Blockages of roads, mountain passes and streams and damage to electric and communication lines are among the direct effects of landslides and snow avalanches apart from injuries and fatalities to human and cattle lives. Blockage of streams and later release of the impounded water create flash floods with disastrous effects. Falling of large volumes of debris from landslides or snow avalanches in mountain lakes can generate flash floods. Snow avalanches create additional suffering due to extremely low temperatures and the associated freezing effect. Even if there are survivors among the victims, they may suffer hypothermia and frost-bite before help arrives.
ii) Indirect Effects and long –term Impacts
Apart from loss of houses, destruction of property and shattering of family life due to death or injury to kith and kin, the indirect effects and long-term impacts of landslides and snow avalanches lead to further loss of productivity (agriculture, poultry, small scale cottage industry, forest produce) in an already marginal productivity scenario.