Research

Mt. St. Helens

Washington
Class X - Natural Condition, Volcano

Mt. Saint Helens - After Blast

Dormant since 1857, on May 18, 1980 at 8:32 am, Mt. St. Helen's in the State of Washington erupted after a 5.0 magnitude earthquake. It had the most destructive force of any volcano in the history of the United States and caused the world's largest recorded landslide. The blast blew 1,300 feet of the mountain down the Toutle River Valley below. Widespread destruction, encompassing 150,000 square miles, was caused by hot gasses, glassier and debris avalanches, mudflows and flooding. The majority of damage occurred in about 10 seconds. Until Mt. St. Helen's, only two known casualties within the United States (one in Hawaii and one in Alaska) had been attributed to volcanoes. This volcano, however, caused 57 deaths. Some that perished simply ignored warnings to stay out of the ten to six-mile "Red Zone", while others were in areas that were destroyed by the unexpected lateral blast of the mountain and resulting floods.

Ninety-eight cabins at the base of the mountain and around Spirit Lake, along with the Boy Scout and Girl Scout camps, the YMCA camp, and other resorts and campgrounds, were covered by debris as much as 400 feet deep. 221 homes along the Toutle River were completely or partially destroyed by mudflows and flooding. 185 miles of highways and 15 miles of railroads were destroyed or completely damaged, and 4 billion board feet of lumber were lost. The loss to wildlife was staggering, including nearly 7,000 deer, elk and bears, and 12 million salmon fingerlings. The property damage and cleanup costs totaled $1.1 billion.

The immediate destructive areas of the eruption, called the blast zone, spanned 18 miles to the north of the mountain, far beyond the six to ten mile "Red Zone" that was initially predicted. Every property within the blast zone was completely destroyed. Even though these homes and cabins were buried under up to 400 feet of debris, some of them later sold for $500 to $750, which was considered a "novelty value". The government eventually condemned these properties and paid the owners the market value for the land, but not the improvements. Some of these improvements were insured, and those that were not were a complete loss.