Mount St. Helens

1
Mount St. Helens

• By
• Chuck Wolfe
• Chris LaPlante
• Matt Chang Madden

2
The Biggest Thing To Rock Washington
Since Metallica!!!
3
The Creation of the Beast

• Created 40,000 years ago
• Created from decite and andesite eruptions
• Most of the Volcanos bulk was created over the
  last 2500 years

4
What, When, Where

• What
• Mt. St. Helens a majestic stratovolcano that
  drew tourists from thousands of miles
• When
• Erupted on May 18, 1980
• Where
• Washington State 46.2N 122.18W

5
The Point is.

• Pre-eruption
• Early effects of the volcano
• The explosion of the Summit Dome
• Pyroclastic activity
• The establishment of pyroclastic activity
• The effect on the land surrounding the volcano

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Taking One to the Dome

• Geothermic activity heated underground water
• Steam gradually built up which resulted in a
  phreatic explosion
• Summit Dome exploded from the pressure, hurling
  material across the landscape

7
She called out a warning

• University of Washington deployed portable
  seismographs.
• So well known that people came to observe volcano
  for pleasure.
• Despite warnings, some people didnt want to
  leave.

8
Active History

• Mt. St. Helens has been dormant for a century.
• Months before the 1980 eruption, seismic activity
  has been recorded.
• Out of the Cascade Volcanic range, St. Helens is
  presently the most active.

9
The Warning Signs To Doom

• Early Effects
• Earthquakes began to increase in quantity and
  intensity.
• This led to the breakup of St. Helens icecaps
• The intrusion of the Goat Rock Dome

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The Beginning of the Calamity

• Second largest eruption in U.S. history

• Predictions come true with the occurrence of a
  5.1 earthquake
• Causes biggest landslide in recorded history

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Pyroclastic

• Pyroclastic flows
• Hot mixtures of volcanic gas, pumice, and ash
• Pyroclastic surge
• Low density surge of pyroclastic material
• Carries less material, but travels at much faster
  
• rates

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Spirit Lake

• Created by previous volcanic activity thousands
  of years ago
• A heavily forested area before 1980 eruption

13
The Destruction of Spirit Lake

• Post-Eruption
• Barren land scattered with ash, tree trunks
  scattered across the area, empty waterbed

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Powerful Nature of the Surge

• The pyroclastic material is capable of traveling
  up to 300 mph
• The temperature of
• the rocks reach 200C to 700C
• Follow indentations of crust (i.e.
  valleys canyons)

15
Range and Effect of the Flow

• The Mount St. Helens pyroclastic flow created a
  15 mile radius of destruction around the base of
  the volcano

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The Conclusion

• The destruction
• Flooding
• Pyroclastic flows
• Melted icecaps
• Mudslides
• Falling debris

17

• Before

After