Geophysical events


  • Anonymous


Mount St. Helens Volcano, Cascade Range, Southern Washington, U.S.A. (46.20°N, 122.18°W). All times are local (GMT − 7 h). Richard Janda of the U.S. Geological Survey calculated that about 2 km3 of debris was emplaced in the north fork of the Toutle River and Spirit Lake by the May 18 eruption. Richard Waitt, also of the USGS, estimated the total May 18 airfall component as 1.1 km3 of unconsolidated material, having a mean bulk density of 0.5 g/cm3. Poor weather has prevented the aerial photography necessary for the production of a topographic map of the post-May 18 volcano. After a map is produced, the amount of material removed from the edifice on May 18 can be accurately determined.