The St. Helens May 18 eruption released 24 megatons of thermal energy. It released more than 0.67 cubic miles (2.8 cubic km) of ash and other material. The collapse of the north side of the volcano shortened St. Helens' height by about 1,300 feet (400 m) and left a volcanic crater one to two miles (1.6 to 3.2 km) wide and half of a mile (800 m) deep. The eruption 