I lived for 10 years within sight (on a clear day, anyway) of Mount St. Helens, and had seen and heard a lot about the devastation caused by the eruption and pyroclastic flow 30 years ago. But I'd heard relatively little about the effects of the ash cloud settling on land. I was surprised to learn about the effect it had on the city of Spokane: basically immobilizing everyone there and every vehicle for days. If you thought the effect of the Eyjafjallajökull eruption on air traffic was serious, imagine what would happen if the ash cloud settled on a city like London or Paris. Check out the slide show below for what happened to Spokane, and extrapolate.
Spokane Spokesman-Review: Mount St. Helens