Mount St. Helens

From the May 18, 1980, eruption to 1986, the volcano erupted an additional 21 times. These were mostly dome-building eruptions, although small pyroclastic flows and mudflows occurred also. During these years, lava formed an 876-foot-high dome inside the crater, with the dome’s volume estimated at 97 million cubic yards.

The volcano was quiet from 1986 until September 2004, when swarms of small earthquakes began. Plumes of steam and ash rose from new vents, ballistic explosions hurled boulders across the crater, and small mudflows traveled down stream channels close to the mountain. A large new lava dome has grown at an impressive rate within the crater. By spring 2005, the newest dome was already taller than the dome formed from 1980 to 1986.

Mount St. Helens has a rich eruptive history, and geologists think that the volcano will likely be active off and on in years to come. The repeated episodes of eruption followed by ecological recovery make Mount St. Helens a fascinating place to learn about the forces of nature and resiliency of life. For up-to-date information on new eruptions, go to http://vulcan.wr.usgs.gov/.