Mount st. Helens, washington, 1980 volcanic eruption: magmatic gas component during the first 16 days.

Eruption plumes of Mount St. Helens, Washington, showed low rates of sulfur dioxide emission, and ash leachates had low ratios of sulfur to chlorine. These data and the nonvesicularity of ash fragments are indicative of only a small eruptive magmatic component. The low amounts of soluble fluorine on the ashes pose no health problems. Violent magmatic activity is possible, and thus continued geochemical monitoring is advised.