|
|
Education
Part of my job is to educate the
community club members as much as I can as to the avalanche
hazard on the Ober Strasse path.
Remember that three conditions must be met to initiate a
slab avalanche.
1.
There must be a weakness in the snow pack that
could fail in order to start the slide.
2.
There must be a load on top of this weakness.
(enough of a load to cause it to fail.)
3.
No matter the weak layer or how much load on top
of it, the weak layer has to be
above the anchors on the slope.
It cannot fail and allow the snow to slide
if anchors such as trees break up the
weakness. This is the most
common situation, which precludes the Ober Strasse
path from sliding. It is infrequent that
we reach snow depths great enough to
allow a slide to potentially
occur. |
Through observations of the
path since 1997 it appears that it will likely take a weak layer
developing on top of a snow pack 10 feet deep in order for a
slide to break loose from the tree anchors.
Once there is a weak layer at this height it would
take an additional 1 to 2 feet of snow breaking free from the
weak layer in order to potentially reach Ober Strasse
Road.
I hope to provide a sense of assurance to
the residents and a sense of security in knowing that high
hazard warnings will likely be limited to those years when we
have very deep snow packs.
Barker Consulting will
monitor weaknesses in the snow pack and continually watch for
any storms that could rapidly increase the snow pack
depth.
Residents will be informed
promptly of any high avalanche hazard warning.
I
want to make sure that residents are not fearful of an
avalanche occurring during every strong storm at low or
moderate snow pack depths.
While residents can
familiarize themselves with the two signs that define the
boundaries of the avalanche path, they should not feel that
this means there is some hazard every time they go past the
signs. The signs will be
changable to show when a high hazard exists.
It is important to note that every year
we are accumulating a great deal more knowledge about the Ober
Strasse path than we ever had before. When the March 1, 1997 slide occurred no one had ever
stood on the slope during a storm and conducted stress tests
or observed loading etc. Since official monitoring
began in 2002 dozens of individual storms have been observed
on site and no movement in the slope recorded at all. This does not mean that a slide could not happen on the
slope, only that we started with the most minimal amount of
information and history on this slide path. From that point, it would have been futile to
accurately predict the behavior of this path in the
future.
In comparison active monitoring since 2002 and assessment of the path
during larch avalanche cycles has shown us many situations in
which the path will not slide.
A slope's avalanche history
is one important factor that avalanche professionals utilize
in predicting when that slope may slide.
The Ober Strasse path has not deposited snow on the
road since March 1, 1997.
In fact we are dealing with
a different slide path than existed in 1997. The path is much narrower in width now with the construction of
the snow fences in 1999.
The path has seen many years of revegetation,
whether natural or replanted.
The path will continue to
change throughout the coming years as tree growth continues to
add an ever-increasing level of stability to the slope.
Tree growth is the key to eventually eliminating the
avalanche hazard on the Ober Strasse path and something I
cannot stress enough.
The snow pack depths necessary for a
slide to reach the road typically do not develop until
February in our large snowfall years.
This is an important part of the education program for
residents and guests.
Residents should be
comfortable with their daily routines and the knowledge that
even in very large storms, if we do not have a relatively deep
snow pack, the stresses in the snow pack will not be able to
overcome the strength of the anchors and an avalanche will not
be able to break free.
Just as the past years
have provided several times more knowledge about the avalanche
path than we had before, the next few years will reveal even
more about how the path will react to a greater variety of
storms and snow pack depths.
It is my intent to not only monitor the
slope for weaknesses in the snow pack, to watch for abnormal
snow cycles, and forecast any possible threat to the road but
to provide a strong educational platform to the ACC which will
increase their confidence as to when the slope will not slide,
so that they can go about their daily routines.
I feel it is important to err on the side
of caution when we have any set of circumstances, which are
likely to threaten the road.
On the other hand I feel I
am not doing my job if ACC members are not cognizant of the
fact that the factors necessary for the Ober Strasse path to
slide to the road just are not present until later in the
season, and some years are not present at all.
An accurate assessment of this path and its hazard will
lead to a better understanding of the program and more
attention being paid when a high hazard warning is
issued.
Too much warning, such as
the signs being out during all the low snow pack times of the
season tends to diminish their validity.
Residents should understand
the parameters that would most likely result in a high hazard
warning, such as, a very large storm on top of a deep
snow pack. A
high hazard warning is not likely with a 24" snowfall on
Christmas.
The members can use this education to
reach a level of understanding that at the start of the year
and in lower snow pack depths all the factors that are
necessary to produce a slide are not present. It will take some time each year for the snow pack to
build up to a depth that would support a slide, if a weak
layer exists and we receive enough input into the snow pack on
top of that.
I hope this provides a
greater sense of understanding and comfort to the
members. Tree growth is the ultimate
answer to the avalanche problem.
In other words as the trees grow the minimum depth
required to overcome these anchors will increase.
Each year at the start of the season it will take a
greater snow pack depth for the path to become a problem.
The window of time when a member's daily routines on
the hill road might become affected will become less and
less.
The possibility of a slide
occurring will only arise at an ever increasing snow pack
depth until the trees are so tall that they provide anchors to
a greater depth than the snow pack reaches even in a large
winter, thus eliminating the avalanche threat. Fire, disease and further logging are all factors that
could reverse this process of trees adding stability to the
slope.
The principal factor in the Ober Strasse
path being able to produce a slide capable of hitting the road
is snow pack depth. It is my hope that the avalanche
monitoring program will not be a mystery to the members, but
that it will shed some light and education on the potential
avalanche hazard not only as to when increased caution should
be used but that members will have a better understanding of
the times in winter when the path is not a threat.
If you have an interest, it is a great
idea to get some formal avalanche education.
There are many volunteer organizations, which hold
classes or you could take a professional course from the
Northwest Avalanche Institute at (360) 825-9261.
There is a great new book about the 1910 avalanche near
Stevens Pass.
The White Cascade by Gary
Krist recounts the avalanche vs. train disaster that still
stands as Washington's deadliest avalanche
event. |
| This Site Developed and Maintained
by: |
| Barker Consulting |
| 34808 Hassinger
Road |
| Lenore, ID.
83541 | |
|
|