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Explanation of the danger levels

The 5 danger levels.

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Swiss federal authoritiesSwiss federal authorities

The hazard categories numbered 1 to 5 have been determined by the specialist government bodies for natural hazards. Prevailing circumstances are outlined in terms of their potential dangers and their impact on society for each individual category within the various natural hazard types. Whilst the definitions have been made as similar as possible for the same hazard category numbers across the different natural hazards, it is, of course, not possible to make direct comparisons between them. Detailed explanations of the hazard categories for each natural hazard can be found here.

Natural Hazards

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Earthquakes

Earthquakes are caused by a sudden release of stress along faults in the crust.

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Frost

Ground frost occurs when the temperature close to the ground (measured 5 cm above the natural ground level) falls to the freezing point or below. This can have certain damaging effects on agriculture and forestry.

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Thunderstorms

Ein Gewitter ist eine komplexe meteorologische Erscheinung. Charakteristisch für Gewitter sind elektrische Entladungen (Blitze) und der nachfolgende Donner.

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Heat

Our perception of heat is affected by the following meteorological parameters: air temperature, radiation from the sun, relative air humidity, and wind.

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Floods

Hochwasser ist ein Zustand, bei welchem Gebiete, die normalerweise im Trockenen liegen, von Wasser überflutet werden.

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Avalanches

Avalanches rank among the greatest natural hazards in the Alpine region. They can affect houses, settlements and transportation routes, as well as people engaging in winter sports.

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Mass movements

Landslides - Debris flows - Rockfalls

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Rain

Rain is the most common form of liquid precipitation from clouds, and develops as a result of small, suspend-ed cloud droplets growing into larger drops of water, which then fall to earth because of their weight.

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Snow

Snow is the most common form of solid precipitation and consists of many very small ice crystals. These form at temperatures below -4 °C, and fall to earth, as long as their falling speed and the temperature and humidity below the clouds do not allow the crystals to melt or evaporate.

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Slippery roads

Ice on the roads develops as a result of cold and wet conditions.

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Forest fire

Given that only 10 percent of forest fires have a natural cause (lightning), it can be assumed that 90 percent of such fires are caused by inappropriate human behaviour (discarding glowing cigarette butts, barbecue fires that are not completely extinguished etc.).

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Wind

Winde entstehen durch Unterschiede im Luftdruck zwischen unterschiedlich temperierten Luftmassen. Vor Wind wird in verschiedenen Gefahrenstufen gewarnt. Sie werden hier erklärt.