Lahars, or volcanic debris flows, appear similarly to debris flows in other environments but may differ significantly in size and origin. Through the work Schmidt (1934) and van Bemmelen (1949), the Indonesian word “lahar,” which refers to highly concentrated streaming combinations of rock debris, mud, and water emanating from volcanoes, was brought into the literature on volcanology. Events classified as lahars can involve mechanisms that are not typically included in the words lahar and debris flow, such as debris avalanches, flood flows, and pyroclastic flows. Here, an avalanche of debris is a flowing mixture of rock, debris, and moisture that slides downslope due to gravity. Debris avalanches are distinct from debris flows in that their weight is solely maintained by interactions between individual particles and they are not saturated with water (Vallance J., 2005).