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DISCUSS THIS FEATURE
HERE
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The 19th of February 2000 was not a good day to
head into the backcountry of the Japan North Alps. A long spell of cold clear
weather had given way to a relentless three day storm from the northwest - a storm
straight from Siberia that continued to gather moisture from the Sea of Japan
while dumping great amounts of snow in the bowls of the Hakuba Mountains. The
ridges were swept clean by the high winds, thus consequently creating a very
uneven depth of snow and pockets of unstable wind slab over the steep lee
slopes. A faceted layer created by the previous long spell of
cold and dry weather lay trapped deep in the loaded bowls and just beneath the
surface and around rocks on the wind scoured ridges. Cornices were loaded and
heavy. That day was a blue bird day with a light breeze and mild rising
temperatures. Avalanche-prone slopes were in prime condition to slide as the
day progressed; all they needed was a trigger.
That trigger came in the form of four snowboarders all placed
in optimum locations to put stress on the unstable slope. As a result, in
the blink of an eye, three people were caught in a size 3.5 avalanche - a force of
nature that could destroy houses and snap large trees in two, and consequently
buried its victims as deep as 5m in a debris of the snow and ice.
They were not the first ones down this time bomb of a valley
this day, but they were the unlucky ones. Two parties, who had gone before them,
scrambled for higher ground in fear for their lives as the wall of white
approached. They were fortunately far enough away not to get caught in the
slide but were covered in 10cms of airborne snow produced by the air blast, a
wind that is created by large powder snow avalanches like this one, and that can
reach upwards of 200 km per hour and hundreds of meters in height.
As the leaders of these two previous parties were
experienced in the winter back country, they returned to see if there might be
survivors of this huge slide that they thought must have been set off by
humans. The other members proceeded out via a service road to relay a distress
message.
The two moved swiftly but cautiously to the debris and the ensuing beacon search that they initiated proved to be in vain as they were told by
the remaining survivor of the accident that the group had not been wearing
avalanche transceivers. A visual search continued by land and by a
dispatched police helicopter which was on the scene within about an hour of
being notified. The search that ensued for the following five days by police,
volunteers, friends, search teams and rescue dog proved hopeless. (Ikeda,
Enright, et al, 2000)
The three boys' bodies were found in the spring by continuing
police surveillance by helicopter, as the snow melted.
Avalanches are acts of nature that are difficult to predict,
even for the seasoned professional, and take close to one hundred and fifty
lives a year around the world. (Schaerer, 1993). There are, however, many things
that we - as back country users - can do to reduce the risk of being caught. We can
also take precautions to provide for a better chance of live recovery if the
unthinkable does in fact happen.
Reducing the risk
* Trip Preparation
A well planned trip is the foundation for success in the
winter mountains.
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Seek information from maps,
guidebooks, ski patrol, knowledgeable locals and guides. |
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Always have a back up plan for if
the weather or conditions turn bad, and don’t be too stubborn to use it.
If in doubt, turn about. (It is sometimes hard to find reliable snow
stability information in Japan and in English. I will try my best to give
what information I can to those who seek it, for the North Alps area. I am
sure other guides and snow professionals will do the same in other areas
of Japan.) |
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If you understand
internationally standardized snow pit data, this can be found on the Japan
Avalanche Network home page;
www.nadare.net. |
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Inform others of your plans,
and fill out mountain itinerary
cards when leaving a resort. |
* Terrain & Route Selection
Route finding is definitely something that comes with years
of experience, yet there are some simple rules of thumb for travel in avalanche
terrain.
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Slope angles of over 25 degrees
can produce slides and 35-45 degree slopes prove to be the most dangerous. |
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Large bowls and valleys produce
large avalanches yet small slopes with deep snow can bury a person just
as easily, especially when combined with terrain traps. |
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Convexing rolls, cornices, wind-loaded slopes, unsupported slopes, openings
below trees or rock outcrops
and solar radiated slopes are all high risk areas and probable avalanche
start zones. |
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Terrain traps such as gullies,
cliffs, trees and tree wells, rocks, creeks, crevasses and human
structures all increase the risk of deep burial, injury and death. Slopes with such
obstacles should be avoided if possible or at least
acknowledged so as to plan an exit if anything goes wrong. |
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Always take into account what
is above you, whether it be others in your group, other groups, crossing
avalanche paths or moving below cornices. |
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When at all possible, stay away
from avalanche terrain when traveling in the back country. |
* Group Management & Decision Making
Most groups are informal groups of friends and do not have a
designated leader thus making decisions for the group a more difficult task.
The best skilled at skiing or boarding may not be the best skilled at making
risk-related judgements or terrain selection decisions for the group. Often
those who are slower or less skilled riders will make better judgements based
on their lower ability or tentativeness, but are often swayed by pressure from
the more aggressive riders in the group. These people may just be following the
tracks of those in front and may not recognize hazards around them.
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When traveling as a group, make
decisions by the whole of the group based on the level of the ability of
each member. If you know that you are going to ride advanced terrain, make
sure that everyone in the group is at an advanced level in the back
country mountains and not only the ski hill - as they are very different. |
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Group spacing in hazardous
areas can reduce the risk of multiple burials (resulting in more difficult
rescue and higher chance of fatality.) |
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Question and double-check
decisions as a group. "What are the hazards? How do we know the
stability of the slope? Why are we doing what we are doing?" |
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Set obtainable goals for all in
the group given the group's weaknesses, weather conditions and snow
stability. |
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Good weather can often be a
false security, enticing people out further and onto bigger and steeper
slopes. |
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Take
into account any signs of instability, and voice your concerns to the
group; you may just save the day and your friends. |
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Backcountry travelers often
become less careful about route selection and snow stability observations
later in the day, especially under poor weather conditions. (Fredston and
others, 1995) |
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Don’t be scared to make the
turnaround decision if conditions are found to be unstable or uncertain.
If in doubt, turn about. |
* Snow Stability & Weather Conditions
In most avalanche-related accidents, people fail to
recognize unstable snow conditions or to heed the warning signs. These range from
obvious indications such as recent fresh avalanches, to hard-to-find weak
layers in the snowpack. (Jamison and Geldsetzer, 1996)
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Get into the snow and see what
is happening. Dig pits, look for weak layers and do tests to determine how
weak these layers are. This takes knowledge and practice and should be
learned from an experienced snow professional, as tests performed
incorrectly can give wrong or misleading information. |
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Make mental and physical notes
of avalanche activity and weather conditions that directly relate to slope
stability. |
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Ask other more experienced
people or other groups what they have been seeing out there. Many
foreigners may have a poor image of ski patrol in Japan, but they are out
there in the mountains every day and have - most often - a better idea of
stability than you may think. |
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Sudden changes in weather can
produce sudden changes in snow stability. i.e., heavy snow fall, solar
exposure, rain, rapid change in temperature, heating and cooling, and
strong wind. |
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Whiteouts due to snow, wind or
fog can cause poor decisions, poor hazard evaluation or poor route finding.
Weather needs to be constantly re-evaluated throughout the
day. |
* Safety & Search and Rescue
There are many things that can increase safety and reduce
the need for rescue from an unwanted avalanche burial. Many of these are
already noted above. Here are some more things to practice and think about.
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Half
the number of buried avalanche victims die within half an hour, and chance of survival decreases greatly
if the accident party has to get help from outside. (CAA statistics) |
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Transceivers must be carried
and turned on at all times when riding off piste or out of the resort
area, and users must know how to use them in the event of an avalanche
accident. |
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Equipment must be easily
discarded or exited if escape from an avalanche is not possible. i.e. ski
poles (straps off), skis (restraining devices undone), heavy packs (straps
unclipped) and snowboard (releasable bindings) |
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One at a time on or crossing
suspect slopes in avalanche terrain or when moving in unavoidable terrain
trap areas. Set spotters. |
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Warm and protective clothing on
and done up, with goggles on in avalanche terrain. |
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Everyone should carry a shovel,
probe, water, spare food, extra warm clothes, a light and a whistle. |
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Practice search and rescue scenarios often. Get good
with your beacon. |
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Common sense is still the best
prevention against accidents. |
Avalanche Awareness Courses
If you are interested in exploring the winter backcountry
you may want to think about enrolling in an Avalanche Awareness Course. These
courses will provide you - and more importantly your friends - with a base of
knowledge and skills that may just save lives out there. The easiest way to be
SAFE, just like with sexual diseases, is to abstain..... which we all know is
virtually impossible! So that is why we learn more, take precautions and stay
with partners whose history we
know, to reduce risks.
Even those with years of riding experience will be amazed by
what they did not know and frightened to think of all the times when sheer luck
and stable slopes were all that got them through unscathed. We have all had
these days yet there is no substitute for knowledge, skill and experience to
reduce the reliance on
luck, and putting more reliance on well informed decisions.
Ignorance is bliss, until you miss.
Play it safe out there and have a great winter, with great
friends and big smiles.
Dave Enright
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