Volcanoes

This feature accompanied the Science Museum's exhibition of A Day in Pompeii during 2007.

Is Mount St. Helens OUR Vesuvius?

Photo by Austin Post, USGS, on May 18, 1980

The eruption was the worst volcanic disaster in US history.

On May 18, 1980, Mount St. Helens erupted. Shaken by an earthquake (5.1 on the Richter scale), the north face of the mountain collapsed in a massive avalanche. Nearly 230 square miles of forest were blown down or buried beneath volcanic deposits. A mushroom-shaped column of ash rose sixteen miles into the sky and drifted downwind, darkening the sky as it fell over eastern Washington and beyond. The eruption lasted 9 hours, but Mount St. Helens and the surrounding landscape were dramatically changed within moments.

The processes, effects, and products were the most intensively studied and photographically documented of any explosive volcanic eruption in the world to date—even shedding light on the eruption of Vesuvius that buried Pompeii.