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Thread: Back to basics

  1. #1
    Join Date
    Jul 2004
    Location
    not far from snowbird
    Posts
    2,245

    Back to basics

    This is just some basic info about avalanches:


    the most common avalanches are point release and slab avalanches. slab avalanches can be wet/dry, hard/soft. dry soft slabs catch more people in the u.s. than any other type. a point release is a slough which can easily push you off a cliff or bury you in a terrain trap. point release slides are easily seen in ski/snowboard videos.

    a point release will typically start at a point and fan out as it entrains more snow. it is unsolidated snow free flowing down the mountain:



    slab avalanche:



    a slab avalanche needs three things in order to release. a slab, a weak layer and a bed surface. since they are the most common, recognizing windslabs can keep you out of trouble when the slab has not bonded well to the old snow. a slab is simply consolidated snow. in a snowpit you can see and feel both the slab and most of the weak layers (surface hoar is the exception) that may fail and allow the slab to release . facets, sun/wind crusts and buried unconsolidated snow all serve as perfect weak layers. an easy test to identify some of these layers is the shovel shear.

    Shovel shear:



    slope angles play a huge part in avalanches. a good rule of thumb is anyting 25-60+ degrees can slab avalanche. 38 degrees is the most common angle for avalanche activity.


    good information
    more stability tests



    this is far from complete but you get the basic idea. please feel free to add to the discussion or post questions. remember that the only dumb question is one that is not asked. others likely have the same question.
    Last edited by AltaPowderDaze; 01-16-2005 at 11:15 PM. Reason: links to pics changed

  2. #2
    Join Date
    Nov 2004
    Location
    Green River, WY
    Posts
    1,081
    Awesome post....good start...hard to believe it hasnít been posted here so concise before.

    This should just get people familiar with things - and hopefully persuade them to take a class(s). There is no substitute for a class, especially one that has a field portion, to see this stuff in the field will really cement it in your brain.

    Beacon practice is also very important - itís easy to screw up even with something like the BCS tracker. I think people should know how to use both digital and old school beacons, since they are so popular you might run into a case where you feel more comfortable giving your digital to someone with an analog.

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