.claim numerous lives every year when people get caught in a wall of snow. There are three main that produce avalanches.The first is the .On top of the snowpack is the icy layer followed by a third layer called the .Having a weak layer of snow lying on top of the ice and bed layers means that an avalanche s more likely to occur.A is needed for the slab layer of snow to . Most avalanches occur on slopes that have angles of 25 to 60 .