The trigger point is the location where a person or machine initiates an avalanche. Possible trigger points include:
- The top of a steep slope;
- Thin areas of the snowpack such as a shallow rocky start zone;
- Locations where the snowpack has reached critical loading through windloading or new precipitation;
- Places where a weak layer is especially weak;
- Places where the snowpack is perforated by rocks or trees.
- Combinations of the above
Fracture lines often connect these areas of weakness or increased stress on the snowpack.