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St. Helens

The powerful lateral blast from Mount St. Helens on May 18, 1980 swept 30 km away from the volcano, blowing down giant trees like matchsticks. The blast, traveling at velocities up to 1100 km per hour, devastated 600 sq km over a broad area nearly 180 degrees wide north of the volcano.

Type/Process: Pyroclastic Flow
Volcanic Status: Historical
Image Number: 028-067
Photographer: John Dvorak, 1980 (U.S. Geological Survey)
Summit Elevation: 2549 meters
Latitude/Longitude: 46.20 N / 122.18 W
Timeframe: Last known eruption 1964 or later
Region: Canada and Western USA


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