Mount St. Helens Eruption

May 18, 1980


Mount St. Helens erupted on May 18, 1980. The volcano, located in Washington, used to be a about 9,600 feet above sea level. The eruption, which removed the upper 1,300 feet of the summit, left a horseshoe-shaped crater and a barren wasteland. Ash continued to erupt for more than nine hours. An estimated 540 million tons of ash drifted into the sky covering seven states. 57 people were killed by the eruption. More than 200 homes were destroyed. More than 185 miles of roads and 15 miles of railways were damaged.

Natural Disaster

Mount Saint Helens was a natural disaster. Saint Helens erupted because of the destructive nature of the margin between the Juan de Fuca oceanic plate and the North American continental plate. Tectonic plates move due to convection currents in the mantle, but movement in a different directions creates different possible margins. A series of several earthquakes then began to occur, resulting in the eruption.

Impact of the Event

  • Local- People who were in close proximity died due to asphyxiation, thermal injuries, and trauma. Some people living near the eruption suffered from post traumatic stress syndrome, troubled sleep, and a sense of powerlessness. Many vehicles were completely covered in ash, completely destroying them. Over 200 homes and 8 bridges were destroyed. Resulting in the most destructive eruption in the US's history.
  • Regional- Shipping was stopped on the Columbia River and some vessels were stranded. Seven surrounding states were covered in ash. Cost a lot in research to determine the cause and when it could potentially erupt again.
  • Worldwide- N/A
Deadly Mount St Helens

Event - Sphere Ineteractions

  • Volcanic eruptions release a large amount of carbon dioxide which may increase photosynthetic production (biosphere). The increase in photosynthetic production can eventually lead to an increase in biomass.
  • Volcanoes release a large amount of hot lava, which causes mountain glaciers to melt (hydrosphere). Mountain glaciers melting will result in excess water flowing down causing flooding downstream from the volcano.
  • After the eruption than is an increase in rain fall, stimulating plant growth (biosphere).
  • The eruption will result in lava being spewed out which will then harden and create more land (geosphere).
  • The eruption released gas into the air which is hard on animal and peoples lungs if in a close proximity, resulting in them dying (biosphere).
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Sphere-Sphere Interactions

  • A plant (part of the biosphere), takes carbon dioxide from the atmosphere and water (the hydrosphere) through its roots from underground (geosphere) to perform photosynthesis.
  • When volcanoes (lithosphere) erupt. Dust and ash particles (lithosphere) spread through much of the atmosphere and block sunlight. Less sunshine can cause a cooler, drier climate in parts of the world.
  • Soil erosion, which occurs when rain (hydrosphere) falls on land (geosphere) by fire or clear-cutting. Streams and rivers (hydrosphere) become muddy or murky from erosion.
  • Plants (biosphere) draw water (hydrosphere) and nutrients from the soil (geosphere) and release water vapor into the atmosphere.
  • Energy from the sun is stored by plants (biosphere).

Effected Areas

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Humans - Spheres - Event Interactions

The volcanic eruption effected the people in surrounding areas due to the excess amount of ash resulting in deaths, ruined homes, and cars being covered in ash. Animals were also affected because their small lungs couldn't handle the large amount of ash being inhaled they died.