At 8:32 am on May 18, 1980, a 5.1 earthquake triggered the greatest landslide in recorded history followed by a lateral blast of 1000-degree super heated pyroclastic gas and rock traveling 450 miles per hour and flattening the forest like toothpicks. Finally, an eruption spewed ash 15 miles into the atmosphere for 9 hours. The ash traveled 60 mph eastward reaching Idaho and turning the day into night.
Melted snow and mud flash-flooded the Toutle River valley carrying a forest of downed trees and boulders. The deposited mud and ash was 150 feet deep in some areas. Over 230 square miles were affected: 185 miles of highway, 47 bridges, 15 miles of train track, and 250 homes were destroyed. It was the largest, most deadliest natural disaster in US history, causing $1.1 billion in damages and taking the lives of 57 people, an estimated 7000 big game, 12 million fish, and millions of birds and small mammals.