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. |
Surface details of the debris (mud) flow on the North Fork of the Toutle River near Coldwater Creek. There is approximately 50 feet of relief between the pond and the mudflow surface. Pyroclastic flows, together with hot ash from nuees ardentes (super-heated masses of gas-charged ash that has been explosively expelled) melted the snow and ice on the flanks of the mountain and created these mudflows. Debris filled the North Fork valley of the Toutle River to a depth of 200 feet. This photo was taken on May 22, 1980. 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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