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. |
Crater and bulge viewed from the east in late April. The bulge on the north-northeast flank was first detected on April 23. By the end of April the bulging area was one mile long and 0.6 mile wide. The maximum uplift had been 320 feet. Some areas on the bulge were moving at the rate of 5 feet a day. 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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