How far did the ash from Mount St. Helens travel?

The May 18, 1980 eruptive column at Mount St. Helens fluctuated in height through the day, but the eruption subsided by late afternoon. By early May 19th, the eruption had stopped. By that time the ash cloud had spread to the central United States.

Two days later, even though the ash cloud had become more diffuse, fine ash was detected by systems used to monitor air pollution in several cities of the northeastern United States. Some of the ash drifted around the globe within about 2 weeks.

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Image shows billowing clouds of steam and smoke emanating from the ground
November 30, 2000

Mount St Helens Phreatic Eruption

Phreatic eruption at the summit of Mount St. Helens, Washington. Credit: D.A. Swanson, USGS

Image shows a map with potential volcano hazards to the surrounding area for Mount St. Helens
November 30, 2000

Mount St. Helens Simplified Volcano Hazards Map

Mount St. Helens, Washington simplified hazards map showing potential impact area for ground-based hazards during a volcanic event. More simplified volcano hazard maps for the other Cascades Volcanoes can be found here.

Mount St. Helens soon after the May 18, 1980 eruption
September 10, 1980

Mount St. Helens soon after the May 18, 1980 eruption

Mount St. Helens soon after the May 18, 1980 eruption, as viewed from Johnston's Ridge.

Volcano erupting and spewing a huge cloud of rock and ash into the sky.
May 18, 1980

Mount Saint Helens eruption

On Sunday, May 18, 1980 at 8:32 a.m., the bulging north flank of Mount St. Helens slid away in a massive landslide -- the largest in recorded history. Seconds later, the uncorked volcano exploded and blasted rocks northward across forest ridges and valleys, destroying everything in its path within minutes.

video thumbnail: Mount St. Helens 1980 Ash Cloud as Seen From Space
May 17, 1980

Mount St. Helens 1980 Ash Cloud as Seen From Space

Eruptive activity at Mount St. Helens captured the world’s attention on May 18, 1980 when the largest historical landslide on Earth and a powerful explosion reshaped the volcano. A volcanic ash cloud spread across the US in 3 days, and encircled the Earth in 15 days.

This mini-movie compiled from individual satellite images taken in 1980 shows the ash cloud as it

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Mount St. Helens

Mount St. Helens

Prior to 1980, Mount St. Helens had the shape of a conical, youthful volcano sometimes referred to as the Mount Fuji of America. During the 1980 eruption the upper 400 m (1,300 ft) of the summit was removed by a huge 

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