Mt St Helens Images - The deposits at the mouth of the Toutle and in the Cowlitz River

The disruption of the transportation network

The late afternoon lahar on the North Fork of the Toutle Rivern was so large that nearly every bridge crossing it was destroyed. One that survived was an older span carrying the Pacific Highway. Flow is to the right in this view. Most of the far bank of the river is covered with dredge spoil.

Photo by James Maynard © 2011 - free use with attribution [full-size jpeg]

Photo by James Maynard © 2010 - free use with attribution [full-size jpeg]

Map showing the bridges in the Mt. St. Helens area. Twenty-seven were destroyed, mostly on the N Fork of the Toutle.

Source: Schuster, H., 1981, Effect of the eruptions on civil works and operations in the Pacific Northwest, in The 1980 Eruptions of Mount St. Helens, Washington, edited by P. W. Lipman and D. R. Mullineaux: U.S. Geological Survey Professional Paper 1250, p. 701-718. 

 

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