When a slab avalanche slides a short distance and breaks down into deeper weak layers forming a stair-step pattern on the bed surface.
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Stepping Down:

When multiple weak layers exist in the snowpack, often a smaller, shallower avalanche will travel a few feet to a few yards and the added weight and stress will trigger a deeper weak layer, which results in a much larger and more dangerous avalanche. These types of avalanches can be especially dangerous to people because the following scenario: First, the person who triggers the smaller avalanche will ride the first slide down. As the smaller avalanche descends, it triggers a deeper avalanche. By the time the deeper avalanche picks up speed and descends to the bottom, the victim has stopped at the bottom of the slope and the secondary, larger avalanche will pile debris on top of the victim, often burying them very deeply with no hope of a live recovery.

When you deal with a snowpack that has the potential to step down into deeper weak layers, it’s important to notch back your level of exposure because of the dangerous consequences.

Additional Terms:
Anchors Hard Slab Avalanche Slide
Aspect High Danger Sluff
Avalanche High Marking Snowpit
Avalanche Path Isothermal Soft Slab Avalanche
Avalanche Transceiver Layer, Snow Stability
Bed Surface Leeward Stability Test
Collapse Loading Starting Zone
Concave Slope Loose Snow Avalanche Stepping Down
Considerable Danger Low Avalanche Hazard Sun Crust
Convex Slope Melt-Freeze Snow Surface Hoar
Cornice Metamorphism, Snow Sympathetic Trigger
Corn Snow Moderate Danger Temperature Gradient
Couloir Persistent Weak Layers Terrain Trap
Cross Loading Point-Release Track
Crown Face Probe Trigger
Danger Ratings Propagation Trigger Point
Deep Slab Avalanche Rain Crust Upside-Down Storm
Density, Snow Remote Trigger Weak Layer
Depth Hoar Rime Weak Interface
Dry Snow Avalanche Runout Zone Wet Snow Avalanche
Extreme Danger Sastrugi Windward
Faceted Snow Settlement Wind Loading
Fracture Ski or Slope Cut Wind Slab
Glide Skinning, Skin Track Whumpf
Graupel Slab