Copyright Information: All images are in the public domain and available for free. If you use this image, credit NOAA/NGDC, Department of Natural Resources, State of Washington. |
Ash-darkened east slopes as they appeared on March 30. This ash was derived entirely from rock pulverized by the explosively-expanding, high-temperature steam and other gases. No new rock material was produced during this stage of the eruption. Note that the location of the ash fall indicates the direction of the prevailing wind. Mount Rainier, another volcanic peak, is visible in the background. Image Credit: Department of Natural Resources, State of Washington 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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