Nothing can be done to stop a landslide once it begins. We examine three of the most terrible landslides in recent history: In California, where heavy rains brought massive amounts of mud into barren, fire-damaged hillsides; in Venezuela, where a series of destructive landslides wiped out a 100-kilometer coastline; and in the small Welsh mining village of Aberfan, where a devastating landslide buried an entire primary school and the students taught there.