2009年3月21日雅思阅读文章

　　Snow Avalanche
　　Avalanche occurs when a layer of snow loses its grip on a slope and slides downhill. Avalanches have killed more than 190 people in the past century in Washington State, exceeding deaths from any other natural hazard. One of the nation’s worst avalanche disasters occurred in 1910 when massive avalanches hit two trains stopped on the west side of Stevens Pass; 96 people were killed. Avalanches kill one to two people, on average, every year in Washington, although many more are i nvolved in avalanche accidents that do not result in fatalities. Since 1985, avalanches have killed 23 people.