Copyright Information: All images are in the public domain and available for free. If you use this image, credit NOAA/NGDC, D. Wellman, NOAA. |
The eruption cloud as it approaches the Yakima, Washington, airport on May 18, 1980. The ash cloud moved at an average speed of about 60 miles an hour and reached the airport by 9:45 A.M., 75 minutes after the start of the eruption. The cloud became so dense that little sunlight penetrated it. Image Credit: D. Wellman. NOAA May 18, 1980 Mount Saint Helens USA volcano An earthquake occurred at 15 32 UT, only seconds before the explosion that began the eruption of Mount St. Helens volcano. This eruption and blast blew off the top of the volcano, reducing its elevation by 396 meters, killed 31 people and caused an estimated property damage of between $0.5 billion and $2 billion. About 53 earthquakes having magnitude larger than 4.5 were located near Mount St. Helens before the main event and eruption. No earthquakes having magnitudes higher than 4.5 were located following the eruption. |
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