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). The devastating May 18 eruption of Mount St. Helens was followed by explosions on May 25 and June 12 that were much smaller but produced substantial ashfalls over wide areas of southwest Washington and northwest Oregon. On June 15, U.S. Geological Survey personnel confirmed the presence of an active lava dome at the bottom of the crater. During the next 4 days the dome grew upward about 6 m/d, reaching a height of 65 m on June 19. No additional growth seemed to have occurred when the dome was next visible on June 28. An eruption similar to those of May 25 and June 12 destroyed this dome on July 22. After a slightly smaller eruption on August 7, growth of a new dome began.