An avalanche is a huge wave of snow, rocks, and ice that falls downhill. Avalanches can hurt people and damage buildings, but there are several things that need to happen for an avalanche to occur. First of all, since avalanches tumble down, they need a steep slope, like a mountain. Since avalanches usually happen on snowy mountains, there are several layers of snow involved, like layers on a cake. Something needs to happen for one of these layers to collapse and pull the other layers down with it. This “something” is called a trigger and can be manmade or natural. An example of a manmade trigger is people doing outdoor sports, like skiing or hiking, or nearby construction. An example of a natural trigger is wind, earthquakes, more snow falling and stressing the layers below it, or the temperature getting warmer and melting the snow, causing the layers to get weaker. Avalanches can be dangerous and scary but also super interesting when you explore the science behind what causes them to occur!