New Zealand Mountan Safety Council

Online Course - Terrain - Terrain Traps

What will happen if this slope slides? Where will it take me?

Terrain traps are places that increase the consequences of being caught in an avalanche. They increase the likelihood of either trauma or a deep burial. Even a small slide with a cliff or rocks in the path can be deadly.

Cliffs

To be knocked off a cliff by a small avalanche can be deadly even if there is not enough snow to bury you. Alot of people die from trauma sustained in the violent tumbling of an avalanche. Climbers are prone to this situation more than most as they spend more time than others on cliff faces. Study your terrain well to see if clliffs are below you, and also if large (unseen) snow slopes lie above your climbing route.


Rocks

If the trajectory of an avalanche takes you over rocks, you are sure to do some damage. Even minor trauma can be a big deal when you are in the backcountry a long way from help. Breaking equipment or yourself will likely slow your progress and will often extend your trip into the hours of darkness. The video below shows how even a small soft slab avalanche carries a huge amount of force, dragging the skier through rocks.


Flat spots/road cuts

Snow will pile up quickly on these bench type features. Below a snow cat struggles to clear heavy avalanche debris piled high on a road cut.


Crevasses

To be swept into a narrow crevasse would almost certainly be fatal as the snow would pile deep above you.


Trees

When large avalanches smash their way down to the bottom of our alpine valleys, trees can act like strainers the same way they do in a river. They can cause major trauma should you be taken into them. In the picture below, you can see how the mature trees have been flattened and snapped by the force of an avalanche.


Gullies or hollows

A confined gully feature allows no escape route, and even a small avalanche will funnel its debris together to increase the possibility of a deep burial.

 

 

Summary - Terrain

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Avalanche Forecast Regions:
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Mountainf Safety Council websiteAdventure Smart websiteNew Zealand Avalanche Center