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Mudslides Explained: Behind the Washington State Disaster

By Brian Clark Howard National Geographic
3/26/2014 8:30:35 AM

The following is an excerpt from National Geographic:

A fatal mudslide in rural northwestern Washington State over the weekend underscores the dangers of this fast-moving natural hazard.

On Saturday morning, a mudslide moved down the Stillaguamish River near the small former fishing village of Oso, Washington. Authorities have confirmed eight dead, eight injured, and as many as 108 people missing or unaccounted for as of Monday morning. The one-square-mile (2.6-square-kilometer) track of the mudslide also destroyed about 30 homes.

This aerial photo of the mudslide near Oso, Washington, was taken Saturday, March 23, 2014. The debris flow was up to 15 feet (4.5 meters) deep in some areas. PHOTOGRAPH BY MARCUS YAM, THE SEATTLE TIMES/AP

Jim O'Connor, a research hydrologist with the U.S. Geological Survey in Portland, Oregon, told National Geographic that the mudslide, which was up to 15 feet (4.5 meters) deep in some areas, was caused by ground made unstable by heavy rainfall.

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