The eruption killed 57 people, in the lateral blast, ashfall, and lahars. The causes to death included asphyxiation, thermal injuries, and trauma. Four indirect death were caused by a cropduster hitting powerlines during the ashfall, a traffic accident during poor visibilty, and two heart attacks from shoveling ash.
The Cost of Volcanic Eruptions details the economic impacts of the eruption.
The Toutle River was flooded by melting snow and ice from the mountain. About 12 million board feet of stockpiled lumber were sweep in the river. Eight bridges were destroyed. 200 homes were destroyed or damaged. Debris dams were added to help control sediment in the rivers.
Thirty logging trucks, 22 transport vehicles, and 39 railcars were damaged or destroyed along with 4.7 billion board feet of timber.
Shipping was stopped on the Columbia River and some vessels were stranded. In eastern Washington, falling ash stranded 5,000 motorist. Ash had to be cleared from runways and highways.
For a limited time, some people living near the eruption suffered from post traumatic stress syndrome: depression, troubled sleep, irritability, ans a sense of powerlessness.
From 1980-1990, 74 research projects were funded by the National Science Foundation at a total cost of just less than $5 million. The Mount St. Helens Visitors Center at Castle Rock cost $5.5 million to construct. Trails, roads in the park, and interpretive centers cost another $42.3 million. New highway and bridges from the Toutle River to Johnston Ridge cost $145 million. facilities along this road will cost another $25 million.
Sources of Information
Carson, R., 1990, Mount St. Helens: The Eruption and Recovery of a Volcano: Sasquatch Books, Seattle Washington, 160 p.
Simkin, T., and Siebert, L., 1994, Volcanoes of the World: Geoscience Press, Tucson, Arizona, 349 p.