What kind of terrain is prone to avalanches?

First of all, the avalanche collapse area, possible travel path and termination area must be identified; large avalanches will also produce smoke and snow areas, and there will be an area of ​​rapid snow dust flow in front of the snowfall. Dry ice collapse is particularly likely to result. This smoke and snow. Some avalanches will pass through a cliff, and some avalanches have unclear areas, especially small avalanches. You must always pay attention to the steep slopes. Even if there are only 10m high slopes above the route, you may still have a fatal avalanche. Although the identification of avalanche terrain was the first to assess the risk of avalanches, many avalanche survivors did not recognize the danger of the terrain. The common misconception was that “there is no avalanche in this part of the hill,” or in a valley, but It is unsuspecting about the steep slopes in the distance.

The following points can help you assess the danger of terrain:

Snow slope: When the slope increases, the snow pressure is also greater. The slope of a typical snow slide is between 25 and 60 degrees, and the most common slope is between 35 and 40 degrees. A slope meter will provide the correct slope value when climbing, which is more useful than your own guess. The slope meter has more benefits. In safe conditions, you can dig out the snow layer and measure the slope of the underlying ice or rock formation. This can tell you the difference between the slope of the surface snow bed and the bottom rock bed, and evaluate the stress of the snow layer.

Snow slope characteristics: Snow slope features include windward or leeward, sunny or dorsal (north-hemisphere north is back-yang, south is sun-facing), and the snow layer is harder on the wind surface, and the leeward surface may develop. In the case of snowfall, the snow conditions on the back surface are relatively stable due to the low temperature, and the snow conditions on the sun surface are greatly affected by the sunlight. If the snow slope is covered by the shadow of the surrounding peaks in the morning, and then it is directly warmed by the sunlight near the noon, the degree of instability is even greater. We must pay attention to it.

Snow slope support: including prominent rock piles, trees, buildings, etc. These supports will keep the slope in a stable state, but it must be noted that if the snow exceeds the height of the support, there is still the possibility of avalanche.

Snow slope appearance: This snow slope is very different? long distance? Or just a small snow slope? A 2km wide snow slope with a gradient of 500M and a slope of 30 degrees, the newly loose snow may not be able to support the entire snow slope and is prone to avalanches. The same slope and new snow, but only a slope of 50 meters wide and 10 meters high, may support the living. . There is a pitfall to be aware of. If you are in a flat avalanche termination area, you usually do not see any danger, but a large avalanche that travels a few kilometers may come straight from the direction you might not expect.

Plant ecology: Forests or grasslands cannot grow on the route where avalanches often occur. Even some pioneer plants are different from plant ecosystems on both sides. Trees that are inclined, broken, or uprooted may be caused by avalanches.

Avalanche history: The avalanche always happens again and again on the same hillside. The problem is when and how big it is. Therefore, more information is collected from people who are familiar with the local environment, such as patrollers, local residents, Laoshanyou, etc. helpful. But remember that human knowledge and experience of avalanche does not accumulate for a hundred years. Compared to the long history and the ever-changing nature of nature, there are still many unknown dangers that need to be taken care of by yourselves.

Is the snow layer stable?

The common snow is not exactly the same. The Eskimo people living in the Arctic region have more than 20 different terms for snow. The deep snow may consist of layers of different layers of snow. Each time the new snow itself has its own density and thickness. In addition, wind blows, solar radiation, and temperature changes are added. As a result, snow layers with different layer characteristics are formed, and the snow layers have different binding forces due to different characteristics. It is an important concept that the stability of a slope is not determined by the strength of the snow itself, but by the binding forces between different layers of snow.

The following points can help you assess whether the snow is stable:

The metamorphism of snow: whether the snow layer is stable or not is affected by the texture of the snow. The crystallization and structure of the snow will change with the external environment factors such as time, temperature, pressure, and other substances (such as water), and each time the deterioration occurs. The effect will have an effect on the strength of the snow layer. It is important that under the same conditions at the same location, different snow layers will develop completely different metamorphism.

The rate of metamorphism varies with temperature, and the higher the temperature, the faster the change. Snow layers with low adhesion are less stable at high temperatures and more stable at low temperatures.