Sure, speeding down well-groomed ski runs can be
fun, but if you like your wilderness wild, the
resort scene may not be your cup of cocoa. Out in
the back country, there are no crowds or
high-priced lift tickets, but there are plenty of
majestic views and wondrous solitude.
Unfortunately, the winter mountains are also home
to one of nature's most violent and deadly
phenomena: avalanches. Knowledge, preparation,
and caution are the keys to survival in avalanche
country.
!! Steps !!
_ Know the avalanche types. There are several
types of avalanches possible, each dependent on the terrain,
steepness, and weather:[1]
* Loose dry-snow avalanches – These can be very large. They start
at a single point and can move at 40 mph / 64.3 km/h, and at that
speed can easily become airborne.
* Airborne powder avalanches – Once airborne at a speed of around
40 mph / 64.3 km/h, these are very destructive and can reach
speeds up to 175 mph / 280 km/h.
* Slab avalanches – If a slab of snow ceases to be supported, it
is easy for it to fall away. Snow accumulates on leeward slopes
due to wind and unsettled snow creates soft slabs that are easily
triggered by avalanche victims. Hard slabs form on lee slopes
where winds are over 30 mph / 48.2 km/h and the slab turns as hard
as concrete. The breaking of such a slab can be heard as a huge
cracking noise.
* Wet avalanches – These are common during spring months or
following thaws, as water weakens any layers of snow, including
down to the ground level. Wet avalanches can be loose or slab,
fast or slow, and set like concrete once they stop making rescue
time for victims extremely short. These often occur following
heavy rain or a snowstorm that starts cold but ends warm.
* Ice avalanches – Ice peels off a crag and falls down the
mountainside.
* Cornice collapse – Cornices (deposits of wind-drifted snow) can
collapse under their own weight, or following a heavy snowfall.
Take an avalanche safety training course and
read up on avalanches. Knowledge is your best
defense against the danger of avalanches, and
there's no better way to gain firsthand
knowledge than by taking an avalanche safety
course. It is also a very good use of time to
read widely on avalanche safety, as there are a
number of good books devoted solely to the
topic, along with many case studies that make
for grim but sobering reading. It has been
shown by research that most victims caught by
avalanches were either unaware of avalanches or
safe route travel skills, or where they did
know, they chose to ignore the warning
signs.[2] Taking an avalanche safety course
won't dent your time much but it could save
your life. Such courses vary widely in price
and scope, and you can choose courses that fit
your primary activities, such as skiing or
snowmobiling.
* Learn how to measure slopes both with tools and without. Learn how
to recognize avalanche slopes. This includes knowing the signs of
previous avalanches on vegetation and other natural features.
* Learn how to evaluate avalanche hazards. This basically consists
of asking: 1. Could the slope produce avalanches?; 2. Could the
snow fail?; 3. What will happen to me if the slope avalanches?;
and 4. Will conditions get worse. A good course should teach you
how to respond to each of these questions and how to to a hazard
evaluation summary.[3]
* Learn how to determine wind direction. This includes noting eroded
features, vegetation leans, build-up of snow, snowfall direction,
rime deposits (these grow into the wind) and sastrugi.
* Learn to ask for local knowledge, especially when you're from out
of the area. It can also be helpful to look at internet records
pertaining to the ski fields where you're headed, to see what
previous seasons have brought by way of avalanches.
Recognize nature's warning signs. The surest
sign of avalanche danger is evidence of recent
avalanches, an indication that local conditions
are right for more. Keep in mind that 95
percent of avalanches occur during or within 24
hours of heavy rain or snowfall, and high winds
also contribute to avalanche formation, so try
to avoid heading off-piste in these conditions.
Particularly warm days, with thawing or
temperatures that approach or surpass freezing,
are also high-risk. Another warning is if snow
cracks, collapses, or makes a "whumph" sound
beneath you; that's a sure sign that the snow
is stressed and can't bear your weight. Any
sudden change in temperature can trigger an
avalanche. Even shadows creeping across the
face of a slope can change the temperature
enough to make snow unstable. If snowballs
(rollerballs or sunwheels) are rolling down the
slope, this is an indication of temperature
increases.
* Low temperatures prolong the chances of an avalanche risk.[4] The
danger remains for at least 48 hours after snowfall and even
longer when it is cold.
* Snowfall at a rate of more than 1 inch or 2cm per hour can
increase the risk of an avalanche.[5]
* The highest danger is on slopes between 25 degrees and 45
degrees.[6] Slopes over 25 degrees tend to be slopes a
fair-skilled cross country skier would avoid skiing down on skinny
skis.[7]
* Note that the convex section of snow will usually be the fracture
zone for an avalanche.[8]
* If there have been recent avalanches, heed them and do not go
anywhere near where these avalanches have occurred, nor near
anywhere with similar terrain and temperatures in the same locale.
Watch for snow gathering on lee slopes of mountains and hills, and
in wind-sheltered gullies.
Pay attention to forecasts and heed
professional warnings. In many mountainous
areas, these forecasts are regularly updated
throughout the avalanche season. You may be
able to find this information on the internet,
on local radio and TV, at resorts and
government offices, or by calling hot lines
(Colorado, for example, has 7 hot lines to
cover different areas of the state). If an
avalanche advisory is in effect, postpone or
reroute your trip. If you're near a resort or
on frequently used trails, signs warning of
avalanche danger may also be present.
* Be wary of any individual who presumes to know better than the
official warnings. This could simply be a sign of foolhardiness or
worse, a sign of over-confidence in their own skills and mountain
knowledge. Try to reason with them but certainly don't join them
if they insist on doing anything dangerous.
Know how to test the snow for avalanche
potential. Before venturing onto a potentially
dangerous slope, find a small, safe slope close
by on which you can perform stability tests.
The test slope should be about the same angle
and have the same aspect as the slope you want
to cross, but it should be small enough so that
the mini-avalanche you may trigger won't be
dangerous. If you can determine that the layers
of snow are well bonded and strong, the slope
is *probably* safe. There are several tests you
can perform, from stomping on the snow to
digging a test pit (tests include the Swiss
ski-shear test, the loaded column test, and the
Rutschblock test). See the "External Links"
section below for more details on precise
tests. In addition, always ask yourself if the
weather is contributing to the potential for
instability.
* Pick a safe trail during avalanche periods of high or extreme
avalanche warnings, or stay home. Safe trails are those which do
not cross over or underneath any slope steep enough to cause an
avalanche.[9]
* Don't rely on hunches, guesses and gut feelings about safety;
evaluate the safety of a slope by your knowledge of avalanche
potential. Ignore avalanche warnings at your own peril.
Be prepared. When traveling into avalanche
country, carrying some simple equipment can
save your life:
* Slope meter: Because avalanches occur almost exclusively on slopes
between 25 and 50 degrees, and 90 percent of avalanches occur on
slopes of 30-45 degrees, a slope meter is the single most
important tool you can have to avoid avalanche danger. Use it to
determine the angle of a slope before attempting to cross or climb
the slope. If the angle is in the danger range, avoid the slope.
* Rescue beacon: Wear a rescue beacon on your top layer of clothing
beneath your coat. Switch in on and test it before you set out.
* Avalanche cord: Before rescue beacons, the primary avalanche
safety equipment was the rescue cord, and these are still useful.
Attach one end of the cord (usually about 30 feet long) and drag
the cord behind you. If you get buried in an avalanche, at least
part of the cord should stay above the surface.
* Collapsible avalanche probes. Every member of a group should carry
probes to search for buried victims in the event of an avalanche.
* Shovels: Everyone should also carry a shovel to dig out people
that have been buried.
* Avalanche Airbag System: These relatively new devices have been
shown to help avalanche victims stay above the surface. Your wear
the system in backpack and pull a release when the avalanche
starts. They're expensive (about $500-1000), but they can save
your life.
Practice avalanche safety while out and about.
There are several key things you can do improve
your chances of either avoiding or getting away
from an avalanche, as follows:
* Study the weather. If you know that the area received freezing
rain, for instance, before the last snowfall the odds of an
unstable slab are much higher. Learn how to recognize conditions
that generate hoar frost and other avalanche promoting conditions
(see how to recognize nature's warning signs above).
* Travel in a group. If you're alone and get buried or seriously
injured in an avalanche, your odds of survival are slim to none
– just don't ski alone in avalanche terrain. Always travel with
at least one other person, and make sure your companions are
trained in avalanche safety and rescue. Try to travel with a group
that is evenly matched for pace, simply because your slowest
member will slow down all of you, which can be hazardous in
avalanche prone terrain. If you have a slow skier in the group,
reduce your ambitions for the day instead of leaving that person
behind.[10] Pair up when skiing down through trees (this will help
prevent problems with tree wells and tree accidents).
* When skiing trails that cross the runout zones of avalanche paths
during moderate hazard warnings, stick to traveling 50 to 100
meters apart on wide slopes, and cross narrow slopes one at a time
just in case an avalanche does occur.[11]
* Cross slopes at the top or bottom, not in the middle. If an
avalanche starts when you're in the middle of a slope, you'll
likely have to go too far to reach safety in time. If, however,
you're near the bottom or at the very top, you may be able to
quickly move out of the way or avoid danger altogether. Stick to
ridgelines – but keep off cornices – or travel along valleys
that give you a wide berth from the slope in case an avalanche
starts above you. If you must go up or down a potentially
dangerous slope, stick close to the edge and go straight up or
down. Don't criss-cross the slope or travel up the middle.
* When resting, rest well away from runout zones of potential
avalanche slopes.[12] Tony Daffern in Avalanche Safety_ warns that
while this seems like obvious advice, many a skiing family is
tempted to enjoy the view from the position of the large, open
snow field which also happens to be the runout zone of an
avalanche slope.[13] The same advice goes for pitching your winter
camp.
* Know when to turn back. Don't push on when the going gets rough.
If it's about to get dark, always turn back. And if the snowpack
is unstable, turn back. You may need to exercise certain mental
fortitude to convince the team to turn back, so prepare your
negotiating skills and be ready to explain the signs and reasons
for not wishing to press on.[14]
Know what to do in the event of an avalanche.
While it is hoped you will never need to have
to try and escape an avalanche, knowing what to
do in the event that you are caught up in one
can give you a greater chance of survival.
Doing an avalanche course is an important part
of knowing how to react in the moments of
becoming trapped in an avalanche. Learn both
avalanche survival and rescue techniques. None
of this is second nature; it must be learned
and is not something you want to be learning
for the first time in the heat of the moment.
* Visualize your escape route. Before you even step foot on a
potentially dangerous slope, scope it out to determine where you
can go if an avalanche happens. Sometimes there may be isolated
areas of safety, such as rock outcroppings or a stand of trees, on
the slope. If not, you'll probably need to cross the slope to get
to safety. Seek the quickest safe way across avalanche slopes, and
have a plan before you attempt to cross them.
!! Video !!
!! Tips !!
* Avoid crossing potentially dangerous slopes
if at all possible. While performing tests and taking safety
precautions may save your life, the only truly safe way to travel
in the back country is to avoid avalanche slopes altogether. If in
doubt, don't go out.
* While loud noises are commonly thought to trigger avalanches,
research suggests that an avalanche caused by sound is highly
unlikely.
* In general, north-facing slopes are most dangerous during the dead
of winter (in the northern hemisphere), but south-facing slopes
become dangerous in spring and during particularly warm, sunny
weather. In the southern hemisphere this is reversed.
* Convex slopes are generally more dangerous than concave slopes,
and the leeward side of mountains, where windblown snow can pile
up by the ton, is usually more dangerous than the windward side.
Trekking atop cornices or right below them is also a bad idea.
Open, treeless slopes are danger zones, but depending on tree
spacing even treed areas may have avalanche potential.
* Snowmobilers account for the majority of avalanche fatalities in
North America, because snowmobiles are heavy and can cover a great
deal more terrain in a day than a person on skis can. The
snowmobile's ability to quickly cover distances, however, allows
snowmobilers to more readily detour around avalanche slopes. If
you are traveling by snowmobile, take advantage of your extra
mobility and avoid danger, even if it means significantly
rerouting your trip. If you're a skier near snowmobilers, pay
extra attention to keeping well away from them if they're crossing
avalanche prone terrain as they may trigger an avalanche.
* High marking on snowmobiles–climbing a steep slope to compete to
reach the highest point–is particularly dangerous. To be safe
avoid high marking, but if you're going to do it anyway, make sure
only one machine is on the slope at a time, avoid parking at the
bottom of a slope, and test the slope's stability first.
* In a pinch, ski poles can substitute for probes, and skis or
snowboards can be used as shovels. These substitutes are not
nearly as effective as the real things, however, so carry probes
and shovels to be safe.
* To protect from hypothermia, wear appropriate warm clothing when
crossing avalanche zones, and zip it up snugly to prevent snow
from entering.
* When traveling in a group, cross dangerous slopes
one-person-at-a-time. While there's safety in numbers, an
avalanche can sweep the whole group away in an instant. If you
must cross an avalanche-prone slope, only one person should be in
danger at any given time, and the rest should watch him or her
carefully.
!! Warnings !!
* The information in this article is a good start to keep you safe
in avalanche country, but it's no substitute for an avalanche
safety course.
* Don't let down your guard or take risks simply because you have a
beacon or because you're traveling with a group of well-trained
companions. Even with the use of the latest rescue equipment and
techniques, a large percentage of people buried by avalanches do
not survive. Prevention is the key to survival.
* Don't wait for professional rescuers to arrive to rescue an
avalanche victim. By the time rescue crews arrive, it is usually
too late to recover a victim alive.
* Don't be stupid. All too often, peer pressure and machismo
contribute to fully-preventable avalanche deaths. If you've got
something to prove, an avalanche slope is not the place to do it.
* A snow pit isn't a guarantee of safety, it is only a best guess.
Localized conditions outside of where you dug your pit can
generate avalanches. You can't dig a test pit everywhere.
* It's a good idea to leave the beginner skiers on the beginner
slopes, always. A skier who is prone to falling down will create a
far bigger dent on unstable snow than a more experienced, advanced
skier who skis lightly.[15]
!! Things You\'ll Need !!
* Rescue beacons
* Shovels
* Avalanche probes
* Avalanche airbag
* Slope meter
!! Related WikiHows !!
* How to Survive an Avalanche
* How to Rescue an Avalanche Victim
* How to Survive a Winter Storm
* How to Drive a Car in Winter Weather
* How to Go Snowboarding
!! Sources And Citations !!
* WestWide Avalanche Network: detailed information on stability
tests,
http://www.avalanche.org/~uac/encyclopedia/stability_test.htm
Avalanche.org – research source
* Snowmobiling safety,
http://www.fsavalanche.org/basics/sled_index.html U.S. Forest
Service – research source
* Colorado Avalanche Information Center,
http://geosurvey.state.co.us/avalanche/Default.aspx?tabid=1 –
research source
* SportScotland Avalanche Information Service,
http://www.sais.gov.uk/about_avalanches/ – research source
* Princeton University Avalanche safety tips,
http://www.princeton.edu/%7Eoa/winter/wintcamp.shtml#Avalanche%20Basics
– research source
* Colorado Mountain Club,
http://www.cmc.org/recreation/recreation_safety_eightsteps.aspx
– research source
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