Pumiceous ash flow of August 7 eruption of Mount St. Helens, viewed from Coldwater Ridge, 8 km north of volcano.
Dates
Date Taken
1980
Summary
Pumiceous ash flow of August 7 eruption of Mount St. Helens, viewed from Coldwater Ridge, 8 km north of volcano. The fully developed ash flow was moving down lower north flank and across pumice plain at about 1629 PDT. Speeds in excess of 100 km/hr were measured from carefully timed 35-mm still photographs and from 16-mm motion pictures. Ash cloud rises above the basal pyroclastic flow Main Plinian column is the higher, more diffuse cloud in background. Skamania County, Washington. August 7, 1980. Figure 15 and Figure 293-C, U.S. Geological Survey Professional paper 1250.
Summary
Pumiceous ash flow of August 7 eruption of Mount St. Helens, viewed from Coldwater Ridge, 8 km north of volcano. The fully developed ash flow was moving down lower north flank and across pumice plain at about 1629 PDT. Speeds in excess of 100 km/hr were measured from carefully timed 35-mm still photographs and from 16-mm motion pictures. Ash cloud rises above the basal pyroclastic flow Main Plinian column is the higher, more diffuse cloud in background. Skamania County, Washington. August 7, 1980. Figure 15 and Figure 293-C, U.S. Geological Survey Professional paper 1250.
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