Dome in Mount St. Helens crater; two USGS geologists (one in orange...

By 1987, the dome had replaced only three percent of the volume removed by the May 18, 1980 eruption. If that rate of growth had continued it would have taken over 200 years to rebuild Mount St. Helens to its pre-1980 size. Instead, Mount St. Helens entered a quiet period which continued until 2004.