The risk of mudflows and floods is greatest on Mount St. Helens during the winter months when precipitation is heaviest and the snowpack is thickest. Students participate in a demonstration that will help them visualize the consistency of mudflows and how they move down stream valleys away from a volcano's summit or flanks. In a work session , students use topographic maps of Mount St. Helens before the 1980 eruptions to forecast the path mudflows might take during an eruption. Volcanic avalanches and volcanic mudflows are somewhat similar, but different in one important respect. Mudflows, however, are mixtures of volcanic debris and water.
Volcanic avalanches lack the water of mudflows.
Mudflows behave differently than avalanches. Because water acts as a lubricant, mudflows travel farther than avalanches. Both avalanches and mudflows can move very fast. Mudflows move downslope and into stream valleys. Being able to forecast the path of mudflows is important to scientists who assess the potential hazards of volcanic eruptions.