  We give a stochastic model for the fragmentation phase of a snow avalanche.
We construct a fragmentation-branching process related to the avalanches, on
the set of all fragmentation sizes introduced by J. Bertoin. A fractal property
of this process is emphasized. We also establish a specific stochastic equation
of fragmentation. It turns out that specific branching Markov processes on
finite configurations of particles with sizes bigger than a strictly positive
threshold are convenient for describing the continuous time evolution of the
number of the resulting fragments. The results are obtained by combining
analytic and probabilistic potential theoretical tools.
