Science Day 2004 FHSU Geology - Predicting Volcanic Behavior at Mt. St. Helens General Background Location - Cascade Range Volcanoes Geologic Setting - Cascadia Subduction Zone Eruption History - last 4000 years Mt. St. Helens Eruptions - 1980-1986 Earthquake Activity Steam Eruptions Ground Deformation Catastrophic Eruption - May 18, 1980 8:32am - lateral blast triggered by M5.0 earthquake and massive landslide - About 60 people killed Smaller Eruptions and Dome Growth Predicting Eruptions Alert Levels for Cascade Range Volcanoes Reading Seismic Signals For More Information USGS Cascade Volcano Observatory News Page Image Gallery of Mt. St. Helens Pacific Northwest Seismograph Network Updates Mount St. Helens volcanocam - US Forest Service Mount St. Helens National Volcanic Monument