In this animation from NASA, observe how rainfall over a slope causes ground saturation that triggers a landslide. The accompanying annotated image calls attention to features of a rotational landslide. Continual heavy rainfall becomes problematic for areas of lower elevation when an upper portion of the ground gets saturated with water and becomes unstable. Gravity causes the saturated soil to move down the slope, creating a landslide. As mud and loose rocks move forcefully downward and outward, they alter the landscape, knocking down trees, tearing apart roads, and damaging everything in their path.
To view the Background Essay and Teaching Tips for this media gallery, go to Support Materials below. This resource was developed through WGBH’s Bringing the Universe to America’s Classrooms project, in collaboration with NASA. Click here for the full collection of resources.