Outline • • Who’s at risk • • Types of avalanches • • What causes avalanches • • Avalanche avoidance • • Companion/beacon rescue • • Educational resources • • Q and A
who’s at risk Snowmobilers lead North America in fatality statistics
who’s at risk Snowmobilers don’t understandthe causes of avalanches
types of avalanches Slab Avalanchescause almost all avalanche fatalities
types of avalanches Point Release Avalanchesmore easily predicted, usually less dangerous
what causes avalanches Understanding what causesavalanches will help you avoid them • Weather • Terrain • Snowpack • Human Factors
what causes avalanches − weather Most avalanches occur duringand after storms New snow adds weight (stress) to the snowpack. New snow takes time to bond to layer underneath.
what causes avalanches − weather Wind transports snow (weight) Loading Cornice Wind loading direction Crown Notice anything else?
what causes avalanches − weather Temperature, elevation & aspectall will affect snowpack stability • Rapidly warming temperatures can weaken the snowpack • You can have stability at one elevation but as you climb or descend the snow profile can change• Similarly, a slope at one aspect can be safe but at a slightly different aspect can be very unstable
what causes avalanches − terrain The majority of avalanches occuron slopes between 30°- 45°
what causes avalanches − terrain Slope shape is also a factor • Most slabs release on thebulge of convex slopes • Slabs can be triggeredfrom above and belowthe slope Convexity Concavity
what causes avalanches − terrain Dense trees can act as “anchors”and points of safety
what causes avalanches − snowpack Weak snowpackusually a strong layer over a weak layer • Learn to evaluate the snowpack • There’s no substitute for on-snow avalanche instruction • Take a Level I avalanche course • Practice
what causes avalanches − snowpack Some slab avalanches are huge
what causes avalanches − snowpack Killer avalanchesmost are small and human triggered 1. What triggered this slide? 2. Where did the slope fail? 3.What’s the slope angle? 4. Where did the debris flow? 5.Could this slide have killed you? 1. Skier 2. Slope convexity 3. Roughly 30 degrees 4. Debris slid into concavity 5. Yes!
what causes avalanches − snowpack Know before you go! • Call local avalanche forecast center • Know the snowpack history • Talk to others who have been out
what causes avalanches − human factors Human factors Attitude:People sometimes ignoredanger signs due to pride,ego and ambition.Time:Weekend warrior syndrome. Blue Sky:Sunny weather sometimesdraws people too soon aftera storm.Herding Instinct:People tend to think less in large groups.
avalanches avoidance Reducing your riskgood sledding habits 1. Expose only one person at a time 2. Stay out of avalanche run out zone 3. Never cross above your partner 4. Have an escape route planned 5. Travel in the same route when possible 6. Keep your partner in sight 7. Travel to points of safety
avalanches avoidance Consider the terrain consequences during route selection Will I get carried over a cliff? Will I get pinballed in the trees? Will I get dragged through sharp rocks? Will I be buried?
companion/beacon rescue Asphyxiation is the primary causeof avalanche fatalities 25% 75% Source: AAA
companion/beacon rescue …but if you get to them fast enough,you can save them If recovered within 15 minutes, chances of survival are almost 92% At 35 minutes, survival rate drops to 37% After that, the success rate is extremely low. Source:AAA (422 completely buried victims)
companion/beacon rescue …and most likely only if you havean avalanche transceiver Search Method Search Time Searchers beacon <15 minutes 1 person search dog 30 minutes 1 trained dog coarse probe 4 hours 20 person probe line fine probe 16-20 hours 20 person probe line Source: AAA Search times in 100mx100m area
companion/beacon rescue If an avalanche occursand you are the victim • If caught, yell so other people see you. Then close your mouth. • Try to ride to flanks of avalanche. Get away from sled if you lose control. • Fight with all of your effort, try to stay on the surface. • As the snow slows, try to thrust a hand upward above the snow surface. • Before the snow stops, try to clear an air space in front of your face. • If buried, do not panic! Stay calm and try to relax.
companion/beacon rescue If an avalanche occursand you are a rescuer • Watch the victim(s) as they are carried down the slope. Look for “last seen point.” • Make sure it is safe to begin a search. • Organize the search party. • Mark the area where the victim was last seen and begin search here. Look for any clues. • Begin beacon search. • When victim is located, confirm depth and location with a probe. Dig fast but carefully.
companion/beacon rescue What do you need for a rescue? 1. Avalanche beacon follows electronic signal to buried victim 2. Probe verifies depth and location of buried victim 3. Shovel removes snow 4. Backpack to carry your shovel and probe
educational resources Resources IASA Avalanche Education Repositorywww.snowiasa.org www.backcountryaccess.com/education www.avalanche.org www.avalanche.ca
Avalanche Avoidance and Companion Rescue Questions?