On May 18, 1980, Mount St. Helens in Washington State experienced a huge volcanic eruption after a magnitude 5.1 earthquake. During the eruption, hot ash and pumice poured down the west, south, and east sides of the mountain, melting the snow and ice at the top of the volcano and creating volcanic mudflows. Which type of change was seen in the ecosystem around Mount St. Helens after it erupted? primary succession secondary succession a climax community species extinction