  We propose a model to study the plasticity of ice single crystals by
numerical simulations. The model includes the long-range character of the
interaction among dislocations, as well as the possibility of mutual
annihilation of these line defects characterized by its Burgers vector. A
multiplication mechanism representing the activation of Frank-Read sources due
to dislocation pinning is also introduced in the model.
  With our approach we are able to probe the dislocation patterns, which result
from the dislocation dynamics. Furthermore, our results exhibit features
characteristic of driven dynamic critical phenomena such as scaling behavior,
and avalanche dynamics. Some of these results account for the experimental
findings reported for ice single crystals under creep deformation, like the
power-law distributions of the acoustic emission intensity observed
sistematically in experiments.
