Check out this excellent video on Strategic Shovelling from Backcountry Access (BAC). It highlights the research done by Dale Atkins and Bruce Edgerly on the most efficient method of digging your buried companion from under an avalanche. Accompanying text from Backcountry Avalanche Safety.
Backcountry Avalanche Safety
An explanation of each level of the Avalanche Danger Scale, including the transitions between levels, signs of instability at each level and the implications of slope angle, aspect and elevation.
Persistent weak layers such as layers of surface hoar, cohesionless facets and old rain or sun crusts are the usual cause of avalanches that release in old snow layers.
Avalanche Forecasts are your primary source of information whether skiing, boarding, snowshoeing, or scrambling and climbing in avalanche terrain.