masses of snow , ice and rocks that move downhill at speeds pof up to 300kmph
loose snow avalanche
a powdery avalanche operating from a single point
slab avalanche
a large scale avalanche formed when a slab of ice and snow breaks away from the main ice pack
causes of avalanche
heavy snowfall
steep slopes
tree removal
temperature rise
heavy rainfall
human factors
if there is heavy snowfall this can cause an avalanche because
this adds to weight of earlier snowfalls
uneven rates of freezing , together with occasional melting can create distinct layers within the snow and ice making slab avalanches more likely to happen as one layer can slip other the other
avalanches are more likely to occur on steep slopes in acess of
30 degrees
the removal of trees for ski developments enables
avalanches to move downhill unimpeded . When present on a hillside , trees can break up an avalanche and prevent it from becoming large
sudden rises in temperature and associated to
melting lead to avalanches in the spring
heavy rainfall can
lubricate a slope and trigger an avalanche
almost all deaths from avalanches kill the people who actually triggered them . Off piste skiing is a major cause of avalanches because it often involves skiing in
areas of fresh snow that have not been assesed for the avalanche
to reduce the avalanche hazard we use
avalanche gully
fences
walls
breaking or retardent mounds
afforestation
wedge
direct protection
avalanche shed
fences and walls
break up the snow
avalanche gully allows
snow to build in the trench before affecting the land
afforestation
roots stop the ice sliding
avalanche shed
acts as a bridge or shelter so that everything underneath it will be protected
breaking or retardant moulds and direct protection
slow down the avalanche and break it up into smaller pieces