When Mountains Rock ‘n Roll: The Inner Rhythms and Lethal Hazards of Debris Flows
with Richard Iverson, PhD, senior research hydrologist at the U.S. Geological Survey’s Cascades Volcano Observatory in Vancouver, Washington
Debris flows are churning, water-laden masses of soil and fragmented rock that rush down mountainsides, funnel into stream channels, entrain objects in their paths, and form thick, muddy deposits when they spill onto valley floors. In some circumstances they are known as “mudflows” or “lahars.” Debris flows have bulk densities similar to that of wet sand but can flow almost as fluidly as water. Because they have peak speeds that exceed 10 meters per second, sizes that can range up to 1 billion cubic meters, and the ability to carry boulders more than 10 meters in diameter, debris flows can denude slopes, bury floodplains, and devastate people and property.
In this talk geoscientist Richard (Dick) Iverson will explain the physical processes underlying the remarkable mobility of debris flows. He’ll describe development and utilization of the world’s largest experimental facility for studying debris flows as well as the chain of reasoning necessary to construct mathematical models for use in forecasting debris-flow hazards. The presentation will include numerous images and video clips of natural and experimental debris flows as well as animations derived from computational models. Particular emphasis will be given to recent debris flows in the Pacific Northwest – and especially to large events at Cascade Range volcanoes.
Richard M. Iverson, Ph.D., is a senior research hydrologist at the U.S. Geological Survey’s Cascades Volcano Observatory in Vancouver, Washington, where much of his work focuses on development of physically based mathematical models for use in debris-flow, landslide, and volcano hazards assessment. He also directs operations and research at the USGS debris-flow flume, a unique experimental facility near Blue River, Oregon. He is a three-time graduate of Stanford University and a Fellow of the American Geophysical Union and Geological Society of America. His fascination with the pull of gravity extends to his favorite avocation, backcountry skiing.
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