Dome building eruption at Mount St. Helens—30-minute, moon-lit expo...

The last dome-building eruption of Mount St. Helens during the 1980s occurred in October 1986. A new lobe was extruded, increasing the dome's height to 925 feet (282 meters), making it taller than a 77-story building. In volume, the dome was nearly 40 times the size of Seattle's Kingdome stadium. The view is from Harry's Ridge, five miles (8 kilometers) north of the volcano.