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. |
Initial crater and ice fractures on March 27, 1980, one day after the first phreatic (steam) eruption. The new vent was about 250 feet in diameter. The fractures crossed the crater on the north and south and ran down the west and east sides of the volcano. 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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