4.3 KiB
| title | tags | |
|---|---|---|
| avalanche |
link: https://www.youtube.com/watch?v=-luspmL_f1o
- Lower risk
- Avoid avi terrain
- safety gear
- what to consider
- using a guide
Reducing risk
- total avoidance (dont go backcountry at all)
- avoidance lite (avoid all avalanche terrain)
- recognising risk, accepting it, minimizing exposure
- use bulletin
avoidance
- stay in bounds/on piste
- use low angle slopes
- steep: 30-45 degrees
minimize exposure to risks
- know if you are in avalanche terrain
- maps, guidbooks, photos
- clinometers
- quality level 1 course
Use the bulletin forecast
- low
- moderate : natural avalanches not likely, man made avalanches possible if you ski in the wrong spot
- considerable: if you ski in the wrong spot, human triggered avalances are likely
no overhead hazard: not below a large face or something
avalanche problem:
- persistent weak layer
- wind drifted snow
whoomps under skis: collapsing snow, avalanches likely
Video 2
link: https://www.youtube.com/watch?v=1r0YIgdjm6M
lots of different types of avalanche. loose vs slab, wet vs dry.
usually: strong snow over weak snow.
strong: often wind effect: ltighly bonded grains weak: light snow with no wind and cold clear nights
important: slope angle
Snowpack tests
link: https://www.youtube.com/watch?v=OvwhuP4qtQg
-
compression test
- locating instabilities near surface
- 30(upslope not horixontal) x30cmx110cm ()
- tap 10 times with finger tips
- mark factures as easy
- level column
- tap 10 times with finger tips from elbow
- level
- tap with hand or fist from shoulder
- facture types video: http://vimeo.com/30996756
-
deep tap test
- similar to compression test but tests only for weak persistent layer relatively deep in the snowpack
-
extended column test
- same as compresion test but 90cm wide not just 30cm
-
rutschblock test
-
propagation saw test
-
shovel shear test
-
hand shear test
equipment
- shovel
- probe
- snow saw
- ruler
- cord
uptracking and route selection
link:https://www.youtube.com/watch?v=RAXgSoSUD3Y
avalanche triangle: snowpack, terrain, weather.
terrain
- 5 red flags: "natures freebies"
- recent avalanches
- shooting cracks
- recent wind loading
- recent snow
- thaw, snow snails
- debris in creeks
snowpack
weather
alptruth
stay far apart so you dont all get trapped.
uptracking
- use google earth
steepness
- caltopo
- hill map
100 with hand vs 1 snow pit
human factor
- familiarity: assuming this are safe because they have been in the past
- acceptance: allowing desire for acceptance (of others) to override decision making process
- consistency: fear of appearing indecisive,
- expert halo: deferring automatically to the expert
- tracks/scarcity:allowing desire to have your day out to influence decisions
develop a routine
Weather and snowpack: slab avalanche formation
avalanches are about timing: know when to go terrain is like a railway track: safe or not safe
snowpack
- can the snow slide
- layered snowpack
- ingredients
- slope
- slab
- weak layer
- trigger
- also
- initiation
- propagation
- weak layers
- new snow
- storm
- wind
- direct-action: hours-days
- persistent weak layer
- depth hoar
- surface hoar
- near-surface facets
- persisten: weeks-months
- new snow
- temp changes during storm can create instabiliies
- upside down: cold then warms up
- right side up: warm then cools
- weak layers between storms
- more persitent hazard
- depth hoar
- easy to see when you dig deep enough
- fall apart in hands
- sugary
- deep in the snowpack
- forms the base of the snowpack
- forms early season
- formed by thin early season snowpack and cold temps
- creates vapour pressure gradient / temperature gradient
- easy to see when you dig deep enough
- near surface facets
- surface hoar