Understanding the complex physics behind an avalanche

Fresh precipitation is the trigger for most avalanches, including the one that killed seven in Sikkim. Avalanches can be loose snow or slab types, depending on the nature of the precipitation, the composition of the existing snow, and the steepness of the slope. Other factors can include slope angle, avalanche path and human activity. Loose snow avalanches usually start at a point and spread in a fan shape, while slab avalanches detach from the existing mass causing larger destruction. A cornice, an overhanging mass of hardened snow at the edge of a precipice, can also trigger an avalanche.