An avalanche occurs when snow packed on a mountain or slope becomes loose and slides down. Several factors, including human ones, contribute to the loosening of snow and ice and the potential for danger to people and property.Know More
Cold temperatures keep snow and ice packed tightly. When a warm front causes snow to loosen, the weight of snow at the top of the slope can start a domino sliding effect. Heavy rain, sleet or snow can also trigger the loosening of packed snow and the start of an avalanche. When snow is more powdery, heavy winds can cause it to loosen and slide.
Movement on and around the slope also triggers avalanches. Earthquakes that shake the ground beneath the snow can cause them. When packed snow is ripe for loosening, even the simple jostling at the top of a slope from skiers and snowmobilers can start the process. Trucks and equipment used in road construction and tree removal at ground level can generate reverberations felt on a snowy slope.
The level of a slope impacts the propensity of an avalanche as well. The snow packed on a high-pitched slope is much more vulnerable to triggers than snow on a flatter incline.Learn more about Earth Science
Snow is a solid. A snowflake is made when tiny ice crystals adhere to one another. Though they can be a variety of shapes and sizes and the odds of two being identical are vanishingly small, snowflakes always have six sides. Under normal conditions, snow is white, soft and fluffy.Full Answer >
Avalanches occur when snow builds up to unstable levels on a steep surface, causing it to slide and fall. This can be due to a lack of vegetation supporting the snow, multiple layers of snow or ice, an increase in temperature or too heavy a snowfall over a short period.Full Answer >
All droughts are ultimately caused by a lack of precipitation. This reduced precipitation does not have to be local; areas that receive water from rivers, for example, can be affected by a lack of precipitation thousands of miles away.Full Answer >
The most common natural causes of landslides include volcanic eruptions, seismic vibrations from earthquakes, erosion beneath banks or cliffs and increases in pore water pressure. Human causes include deforestation, alterations to natural paths of drainage, pipe leaks and other activities placing significant pressure on landforms.Full Answer >