Lessons from Mt. St. Helens














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On May 18, 1980, a major volcanic eruption took place at Mt. St. Helens in Washington

  • The entire north face of the mountain was destroyed or collapsed, creating the largest landslide in recorded history
  • An eruption cloud rose 80,000 feet into the atmosphere, depositing ash across 11 states
  • An entire glacier that was atop the mountain was quickly buried and subsequently vaporized
  • An enormous mud slide was created that reached as far as the Columbia River, some 50 miles away
  • Tens of thousands of animals died; perhaps millions of fish
  • 57 people lost their lives 1

Estimates are that 2/3 cubic mile of rock collapsed during the eruption

  • The energy release was equivalent to 400 million tons of TNT or the equivalent of 20,000 atomic bomb detonations
  • 150 square miles of forest were destroyed in just about 6 minutes
  • The Rock Slide crashed into Spirit Lake just below the Mountain, which resulted in a tidal wave that crested at just around 850 feet 2

The eruption resulted in so many new geologic formations in such a short period of time

  • As a result, geologists had a living laboratory to test how a catastrophe could rapidly give rise to formations that previously were thought to take great amounts of time


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