Card Set Information
Avalanche Terrain Terminology
4. Deposition zone
5. Bed Surface
Upper margin where the slide broke away from the rest of the snow pack
The left and right borders of the slide.
The bottom (downslope) boundary of a slab where it rides up over the snow below. Usually difficult to impossible to identify after an avalanche.
4. Deposit zone
where the slide stops moving and ost debris is deposited
5. Bed surface
the surface on which the snow slides.
2 Main Avalanche Types:
1. Loose Snow
1. Loose Snow
: usually caused by fresh snow >12''. often referred as sluffs, can run fast and far depending on terrain.
: Similar to dry loose avalanche, however conditions are caused by rain or rapidly warming temperatures.
Most dangerous and devastating
: usually caused by rain or prolongd warming on dry snow.
: usually caused by >12'' of new snow in 24hrs or less
: usually caused from moderate winds (10-20mph) transporting snow which loads the leeward aspects.
: aused by persistent layers of strong hard slabs surrounded top and bottom by weak snow.
: caused by weak layer buried deep (3') in the snow pack. usually triggered by a large load such as a cornice fall or explosive.
Relative to Path:
: very small (0-20%)
: small (20-40%)
: medium (40-60%)
: Large (60-80%)
: Major (80-100%)
: Too small to injure of bury a person
: Could bury, injure or kill a person
: Could bury, destroy a car, damage a truck, destroy a small bldg., or break a few trees.
: Could destroy a truck railway car, several bldgs., or up to 10 acres of forest.
: could destroy a village or 100 acres or more of forest
Slope Angles: 0-25°
infrequent wet snow avalanche, green slopes
Slope Angles: 25-30°
Infrequent slabs in unstable conditions, blue slopes
Slope Angles: 30-35°
Slabs in unstable condition, Black diamond slopes
Slope Angles: 35-45°
frequent slabs of all sizes , double black diamond slopes
Slope Angles: 45-55°
many loose avalanches start, some small slabs, out of bounds
Slope Angles: 55°+
Few avalanches, climbing terrain