Each year, landslides kill more people and cause more property damage than all other natural disasters combined. In this program, experts from the U.S. Geological Survey examine the causes of these deadly phenomena and discuss new ways of predicting their occurrence. Using experiments, newsreel footage, and engaging computer graphics, geological engineers illustrate how water pressure built up in a slope can unleash debris flows up to 100 miles per hour. Interviews with witnesses and survivors of major landslides further emphasize how gravity inevitably prevails over all other geological forces. A Discovery Channel Production. (53 minutes)